Category Archives: 2025

Plant Spotlight – Grasses of Trinity

Posted on by
Oak woodlands near Weaverville in 2020. [Kiana Abel, Trinity River Restoration Program]

As the weather starts to warm, California’s hillsides turn golden as grasses dry and take on a reflective sheen. Not only does California’s nickname “the Golden State” refer to it’s historic connection to the gold rush, it also refers to the rolling golden hills of native flowers, like the California golden poppy and less distinct but no less important the native grasses of California. California’s grasslands are a subtle and complex community of individuals which each invite the passerby to slow down and look carefully. One can also trace the last vestiges of water and see where the moisture lingers on the landscape. These last little patches of green show photosynthetic organisms reluctant to take shelter from the summer heat.

Historically it was farmers who were in touch with the detailed eye and mind tuned to the life cycle of grasses. To be a farmer who makes hay, is to understand the boom-and-bust lifecycle of being a grass. As many ranchers will say – being a rancher is really learning to be a grass-farmer. It is an intimate relationship to learn the rhythm of grass growing, to slow down and tap into the cycle. There is a critical threshold in the season, where all the grasses race at a break-neck pace to produce seed. As part of a grass’s strategy, it tracks day-by-day weather in a race to produce and distribute seed in the heat of summer. As a hay producer, it’s best to harvest your hay before all the energy has gone up into the seed and hardened off. This will allow some of the sugars to be readily available for consumption when an animal goes to eat it. If the grass is too far along towards producing its seed, the sugars in the grass become all locked up and stored into their long term, harder to digest form.

image
Diagram of grasses. [Photo credit: PlantNet Diagram: SWL Jacobs Taxon Concept]

If you’ve ever been curious about grasses, Trinity County has some beautiful remnant examples of grasslands clinging on to the edges of areas where mining did not bury their seeds beneath the sorted rocks. When identifying grasses, I find that it can be easiest to start with the things that you’ll see a lot of and try to find “friends” in the population. Each person relates to plants differently, but I find that it can help to try to find a few native grasses and a few non-native grasses to learn to train your eye to their differences. Knowing a handful of native and a handful of non-native grasses is a great place to start.

Comparing grass cousins

Bromus diandrus or rip gut brome. [iNaturalist]
California Brome Bromus carinatus. [iNatrualist]
image

Here is Bromus diandrus or “rip gut brome” so named for its ability to get the long awns of the plant (the bristle or hairy growth that helps carry a seed) all tangled and poking into the skin, mouth or gut of herbivores munching in grasslands. Rip gut brome was introduced to California from European Mediterranean areas and is considered invasive and harmful to crops and foragers alike.

Because grasses are difficult to discern, I’ve noted to visit and reexamine them as the season progresses. With each stage of development from flower to seed each species can change significantly showing their true colors. As Bromus diandrus develops it changes colors and can look quite purple.

image

Here’s a common native grass that looks quite similar to Bromus diandrus. A cousin to B. diandrus, this is Bromus carinatus or California brome which is a native bunch grass that can be found quite often in many types of habitat.

California brome pollinates via wind, is a great asset in erosion control and is well adapted to survive under a regime of frequent fire. It is also an important food for bear, elk, black tailed deer and seed eating bird species of California.

Look closely when comparing these two brome species by looking at the hair-like awns sticking out of the flower.

In this photo Bromus carinatus is on the Left and Bromus diandrus is on the right. [Simone Groves, Hoopa Valley Tribal Fisheries Department]

Non-Native Grasses

As livestock were introduced to California farmers often seeded grasses as forage so their animals would be well-fed where they landed. The easy and short list of these species is a great starting place for starting to recognize grasses. These species include Orchard Grass (Dactylis glomerata), Rye grass (lolium perenne), Wild Oats (Avena sp). Avena or wild oats are the same oats that we eat for oatmeal or give to our horses for grain.

Orchard Grass (Dactylis glomerata). [iNatrualist]
Rye grass (lolium perenne) [iNaturalist]
Wild Oats (Avena sp). [iNaturalist]

Native Grasses

And now for some of the native species of grasses! There are three classics to get to know in our area which are blue wild rye (Elymus glaucus), California oatgrass (Danthonia californica) andpurple needle grass.

image

Blue wild rye (Elymus glaucus)

This grass is a tall hearty looking grass with a large seed. It’s very hard to photograph the whole seed head because it is so long and tall, but once you get to know this plant it’s quite distinct. Blue wildrye provides excellent habitat for birds, mammals and waterfowl, can be used to stabilize streambanks, and is very tolerant to fire. Early in the season it provides forage and the seed is an excellent summertime food source for native mammals and birds [USDA Blue Wildrye (Elymus glaucus) Plant Guide].

California Oatgrass (Danthonia californica)

Danthonia as the genus that represents a variety of native oats, and when you tune your eye you’ll notice slight variation within the group along with some similarities. Their inflorescence (arrangement of the flowers on a plant) is composed of 3-5 spikelets and it is a pretty distinct recipe once you start to recognize it. They have relatively short peduncles (stalks that hold the flower or seed), only about 1-2 feet above the ground and their most distinctive feature are their “hairy arm pits.” Danthonia tends to have very hairy leaves and sometimes particularly long hairs right where the leaf separates from the stalk. Danthonia also looks to me like a little field of tiny stars, as they stand in such a distinct pattern along the ground.

California Oatgrass (Danthonia californica). [iNaturalist]

Purple Needlegrass (Stipa pulchra) (Nassella pulchra)

Lastly, Stipa pulchra, recently renamed to Nassella pulchra and commonly known as Purple Needlegrass is a grass that I – personally as a plant person – have heard a lot about throughout the state. Purple needle grass is the most widespread native grass in California and was named the “state grass” in 2004. In my experience I’ve have never seen it doing quite as well as the populations you can find here in Trinity County. This plant has long awns similar to rip gut brome but is soft to the touch while brome is typically quite coarse and harsh to the touch.

Purple needlegrass is drought tolerant and produces a lot of seed which helps to suppress non-native grass species.  This grass supports native oak habitats and provides nursery habitat for caterpillars and butterflies of California.

Getting to know grasses is a process of revisiting them frequently to see the way that they change through the year. Touching and observing their basal leaves versus their flowering stalks can help you get to know the ways that they are similar and different from each other. To me, the jovial angle that each grass holds its seed is an expression of its personality and projects attitude. As the seeds mature, usually the stems of the grass start to grow heavy, and once the seeds are dispersed, they’ll spring back up again.

Grasses are a huge part of the plants that we see in our daily lives. Their role creating tiny holes for insects to live in and deep roots which hold our soils together are foundational to a healthy landscape. It’s easy to overlook the niche of grasses when we all spend much of our time trying to weed whack them down. I encourage you to try to take that extra moment to see if you can identify if a grass is native or non-native, bunchgrass or annual grass. These little details are small pieces of history that we used to know in times long past.

References

Simone Groves, Riparian Ecologist, Hoopa Valley Tribal Fisheries

Simone is first generation California transplant of scottish descent raised in the unceded territories of the Raymatush in the rural west peninsula of the SF Bay where farmers, farm workers and hippies form the heart of the small town. She graduated in 2016 from Humboldt State University with a BS in Botany and has worked in the outskirts of rural Humboldt county on Natural Resource and Land management since 2013. She is passionate about plants and their interactions with dynamic systems as a mechanism for relearning our human-landscape interdependence.

Bats of the Trinity River

Posted on by

Wait, bats? Of the river? Yes! A river is more than its bed and banks, it is also intricately tied to the valleys, canyons, and forests through which it flows. Many North American bats are tightly associated with proximity to both forest cover and water (e.g. Dixon 2012), and the bats of the Trinity River watershed follow suit. In fact, some of our bats do almost all of their foraging over and near water, which in a dry, mountainous landscape like ours, means over the Trinity River and its tributaries.

Bats fly into a Texas sunset. [US Fish and Wildlife Service]

Bats are the second largest order of mammals in the world, with >1,400 species on every continent except Antarctica, though a majority of those species are in the hyper-diverse tropics. The Klamath Mountains, through which the Trinity River flows, are home to at least 18 species (Reiss, Kauffman, and Feldman 2022). Some of these are year-round residents and are known to hibernate locally, whereas others migrate to warmer climates during the winter. All of our local bat species echolocate, meaning they essentially “yell” in very high frequency sound and then listen for the echoes (the same concept as sonar), which helps them navigate and feed in a dark world.

While the incredible worldwide diversity of bats includes many unique feeding styles such as nectar-feeding flower pollinators, fruit eaters, and (a bat fan favorite) bats that fish for food like the super cool fish-eating myotis, all of the bats in the Trinity watershed eat invertebrates like insects and spiders. That said, there’s a remarkable range of ways that they do that. Let’s take a look at a few of the species that call the Trinity River watershed home.

Myotis species

A little brown bat. [USFWS/Ann Froschauer]

Of the bats discussed here, the five or more small, brown, round-eared species of Myotis in our area are perhaps the closest to what people think of when they think of a “bat”. Their appearance exemplifies the German word for bat, Fledermaus or “flutter mouse”, though bats are much more closely related to deer, whales, and carnivores than to rodents.

Yuma myotis (Myotis yumanensis) are among the most frequently encountered species in the region and are “aerial insectivores”, meaning they forage on flying insects. They can be found flying along forest edges but most commonly over slow-moving water, typically only a couple feet above the river. This is because while they will also take things like moths and beetles, they are strongly predisposed to hunting emerging aquatic insects like caddisflies and midges. They make low, repeated passes over water smooth enough for their echolocation to detect the disturbance of insects on the waters’ surface. In areas where few large trees are found, they will form maternity roosts in buildings; these are where large groups of females gather together to raise their pups until they are old enough to disperse. However, in areas of the West including parts of the Trinity River where there are healthy riparian areas with large, old trees, they will roost in things like hollowed-out old cottonwood trees. This is one of the reasons that the Trinity River Restoration Program attempts to avoid impacts to mature riparian forests when building our restoration projects.

image
Myotis yumanensis (Yuma myotis) (11362476624) – Yuma myotis – Wikipedia]

Another Myotis worthy of note is the little brown bat (Myotis lucifugus). While they are less abundant than Yuma myotis in the Trinity River region (Pierson and Rainey 2007), they are strongly predisposed to roosting in buildings and thus relatively commonly encountered. They are noteworthy in that, while fairly generalist in their feeding habits, they eat disproportionately large numbers of mosquitoes, making them allies of their human neighbors (Wray et al 2018). They have quite a large range, extending from the subarctic to the southern US, and through the late 2000s were among the most common bats on in North America. However, they are now classified as endangered by the International Union for Conservation of Nature because of the catastrophic impacts of an introduced disease called white-nose syndrome; it is estimated that the eastern and midwestern populations of the species have declined by 90% since 2010.

Little brown bat (Myotis lucifugus) in a historic building. [Mike Dixon, Bureau of Reclamation]

Pallid bat

A pallid bat (Antrozous pallidus). Photo originally posted on ANAMALIA by Michael Durham/Minden Pictures, BCI

In contrast to the myotis bats described, pallid bats (Antrozous pallidus) are quite large, with a wingspan of up to 16 inches. Beyond their large size, they also have enormous ears that can be a third of their body length. This is because rather than catching insects on the wing, they are gleaners, meaning they hunt prey on structures or, in their case, the ground. They are still capable of echolocation, but their over-large ears also allow them to listen for the sounds of their prey and target them that way. They are particularly fond of scorpions, of all things. Their inconsistent use of echolocation and ground-hunting behavior also means they tend to hunt in more arid or open areas, but they still stay relatively close to water. They frequently roost in trees in northern California (Baker et al. 2008) but can also be loyal users of strategically located buildings as night roosts. Night roosts are places that bats hang out for a variety of reasons including rest, digestion, picking apart large prey items, and various social interactions including information sharing (Ormsby et al. 2007). For several years, I have observed congregations of 5-20 pallid bats in the same corner under my eaves almost every night when overnight lows temperatures exceed 45oF. I appreciate them keeping the front of my house scorpion-free!

One fun fact about the pallid bat is that it is officially the state bat of California!

Pallid bats (Antrozous pallidus) have frequently used this night roost on a cabin next to the East Branch of East Weaver Creek. [Mike Dixon, Bureau of Reclamation]

Hoary bat

Hoary bats (Lasiurus cinereus) are striking in appearance. Rather than the shades of brown with which bats are often portrayed, the hoary bat has dark fir with brightly frosted tips and a yellowish face. Also unlike many bats of the temperature regions, it doesn’t hibernate – rather, it spends its summers from the northern U.S. (including northern California) well into Canada, and then in the fall migrates sometimes over 2,000 km south to a winter range that extends from the Southwest into Central America (Cryan et al 2004).

A hoary bat (Lasiurus cinereus) roosting on the branch of a tree. [Paul Cryan USGS]

Rather than flying low over the water or ground or on the edges of forest, the hoary bat is a high-flying moth specialist that makes long passes over open water or the top of the forest canopy, sometimes flying almost 25 miles in a night of hunting. The coevolution of bats and moths has been a subject of long study, as there is evidence that echolocation by moth-hunting bats drove the evolution of ears and evasive behaviors in moths, which in turn changed how moth-specialist bats echolocate (Ter Hofstede and Ratcliffe 2016).

Hoary bats are more solitary than most of our bats and tend to roost individually by hanging from tree branches like dead leaves, but they can form large aggregations around landmarks during their long southward migrations. This means that after they leave our Klamath Mountains, they are often recorded in what would seem to be pretty unusual places for a bat – they have been observed swarming ships at sea and commonly recorded over the Farallon Islands 30 miles off the coast of San Francisco.  These long, sometimes over-water migrations also presumably led to one of the more unlikely events in the history of bats – the colonization of the Hawaiian Islands over 1.3 million years ago by hoary bats from what is now the west coast of the U.S. In this single founder event, wayward bats established the most isolated bat population in the world, which has since diverged significantly into its own species, the critically endangered Hawaiian hoary bat (Lasiurus semotus).

Bats and people

I have already mentioned how a couple of our native bats benefit people by controlling pests, and that topic has been the subject of many publications. Suffice it to say, bats are very important to the ecology of the Trinity River watershed and provide services to its people here and throughout the world, but they can also be inconvenient and, occasionally, dangerous to people. Here are a few suggestions for living with bats.

  • First and foremost – while bats don’t “carry” rabies (it is also deadly to them), the abnormal behavior of rabid bats is what often brings them into contact with people. NEVER pick up a bat that you encounter. It is unlikely that it has rabies, but the consequences of contracting rabies are so serious that it is not worth the risk. If you encounter a bat in your house, shoo it out but do not handle if it all avoidable – you’d be surprised how thick of a glove a bat can bite through!
  • If you have the space for it, embrace an untidy yard. Long grass provides a home for large insects like crickets that are preyed upon by our gleaning bats. Leaving fall leaves until the following spring allows many types of caterpillars and beetle grubs to use them as winter cover, providing food for our aerial insectivores the following summer. Trees with loose bark cavities or large are used by many species for roosting and can be left as habitat where they do not cause a hazard.
  • Many species like to use buildings for day or night roosts or for hibernation. Sometimes this isn’t a huge deal – I already mentioned that I appreciate the night roost above a seldom-used door at my house, and even use their guano as a garden amendment. However, in confined spaces like the walls and attics of buildings, the guano can become smelly and damage walls, and bats roosting in those places sometimes find their way into parts of those buildings with people (not a good thing, as already discussed). Many pest control companies have experience with excluding bats in a humane way (essentially letting them fly out but not back in). If you need bats evicted from your home, try to wait until late summer when the pups have fledged, so as not to separate foraging mothers from their flightless pups.  
  • If you’d like to encourage bats to use your property, you can build or buy prefabricated bat houses. The trick in a climate like that of the Trinity watershed with sometimes intensely hot days and cool nights is to find the right sun exposure. Nursing mothers and pups want a spot that will gather and retain heat into the evening but will not get so hot during the day as to be uninhabitable. There’s an element of trial and error (and luck) to getting bats to move in, but it’s a great way to provide wildlife habitat and help keep your bugs down. For more resources on gardening and bat houses, this is a great place to start: Bat Gardens & Houses – Bat Conservation International.

References

Baker, Michael D., Michael J. Lacki, Greg A. Falxa, P. Lee Droppelman, Ryan A. Slack, and Scott A. Slankard “Habitat Use of Pallid Bats in Coniferous Forests of Northern California,” Northwest Science 82(4), 269-275, (1 September 2008). 

Dixon, Michael D. “Relationship between land cover and insectivorous bat activity in an urban landscape.” Urban Ecosystems 15 (2012): 683-695.

Ormsbee, Patricia C., James D. Kiser, and Stuart I. Perlmeter. 2007. Importance of night roosts to the ecology of bats in Michael J. Lacki, John P. Hayes, and Allen Kurta, eds. Bats in Forests – Conservation and Management. The John Hopkins University Press: pp 129-151.

Pierson, Elizabeth D. and William E. Rainey. 2007. Bat distribution in the forested region of Northwestern California. Report for California Department of Fish & Game, Contract #FG-5123-WM.

Reiss, Karen, Michael Kauffman, and Chris Feldman. Mammals in Michael Kauffman and Justin Garwood, eds. (2022). The Klamath Mountains – A Natural History. Backcountry Press. Pp. 428-430.

Ter Hofstede, Hannah M., and John M. Ratcliffe. “Evolutionary escalation: the bat–moth arms race.” Journal of Experimental Biology 219.11 (2016): 1589-1602.

Wray, Amy K.; Michelle A. Jusino, Mark T. Banik, Jonathan M. Palmer, Heather Kaarakka, Paul White, Daniel L. Lindner, Claudio Gratton, and M. Zachariah Peery, (2018). “Incidence and taxonomic richness of mosquitoes in the diets of little brown and big brown bats”. Journal of Mammalogy. 99 (3): 668–674.

Mike Dixon is the Executive Director of the Trinity River Restoration Program and a northern California native. He fell in love with the Trinity River and Klamath Mountains while assigned to his first duty station at Coast Guard Air Station Humboldt Bay. He received a Ph.D. in Conservation Biology from the University of Minnesota, Twin Cities, where his dissertation focused on the landscape ecology and population genetics of bats. He lives on a small, perennial tributary of the Trinity River near Weaverville.

Photo: The [much younger] author with a little brown bat in Voyageurs National Park

Animal Spotlight – Northwestern Pond Turtle

Posted on by
image

The northwestern pond turtle (Actinemys marmorata) has lived in the waters of the Trinity River for thousands of years. This species has undergone several taxonomic revisions since first being first described in 1841 (1, 2, 3).  It was originally considered a single species with the southwestern pond turtle (Actinemys pallida) and called ‘Emys marmorata’. Then both species were renamed ‘Clemmys marmorata’. The northwestern and southwestern groups were more recently split into two species based on genetic and physical differences between them. So, you may read our local turtles described with different common and scientific names depending on when the document was published (3). But no matter when it was published, there is only one native freshwater turtle known to the Klamath Mountains and the current name is “northwestern pond turtle” (Actinemys marmorata).  

Photo: A female northwestern pond turtle. [Don Ashton] 

Actinemys marmorata 

actin = ray or beam // emys = turtle // marmorata = marbled

As its common name suggests, the northwestern pond turtle is known to inhabit ponds and lakes, but within the Klamath Mountain ecosystem they are commonly associated with riverine habitats. Northwestern pond turtles are poikilothermic, meaning that they regulate their temperature by basking in the sun when they are cold, and seek cool water or shade when they are too warm. They distribute in sunny, slow water reaches with boulder lined pools that, importantly, have connectivity to broad floodplain habitat (5, p. 353).

A male Northwestern Pond Turtle in underwater refugia on the Southfork Trinity River. [Don Ashton]

The northwestern pond turtle has an acute sense of sight and low-frequency hearing, and while they are often seen basking in the sun above water, they will quickly retreat when they feel threatened (5). Reader, a river enthusiast we surmise, we are sure you’ve witnessed the sound of a plopping western pond turtle off a river log – but did you see them? 

Male turtles are known to migrate from river to upland areas to overwinter in riparian shrubs or leaf litter. This trait is not ubiquitous among all turtles as some choose to stay close to their summer habitat by overwintering in banks near the river or pond. Local herpetologist Don Ashton of McBain Associates/Riverbend Sciences has spent decades studying turtles in the Trinity River and said, “Turtles are very smart animals, they tend to migrate close to the high water line (think 100 year floodplain) but over time we have found that in comparison with North Fork Trinity River populations, turtles on the mainstem are found more frequently hibernating and nesting in lower elevation areas, likely due to adaptation of minimized flooding by Trinity and Lewiston Dams.”

In addition to migration for hibernation and summering, female turtles migrate twice for nesting. When they are ready to lay their eggs, they fill their bladders and set off on a slow but steady journey to upland areas to dig their nests. Once in a satisfactory location, the female turtle wets the ground with her urine to help soften it for digging. Once her eggs are laid, she will journey back to her summer habitat.

A Northwestern pond turtle nest, predated. Egg fragments and plug are identified. [Don Ashton]

Migration to upland areas for nesting or hibernation can often lead to chance encounters with humans or their vehicles. If you happen to cross paths with a turtle, Ashton advises to leave them to their journey, “they are not lost” Ashton declares. However, if their location poses a risk of vehicular homicide, and you feel compelled to move them, point them in the direction of their path. That is unless the turtle happens to urinate while being handled, then, Ashton suggests, they should be pointed back toward a water source.

These ancient creatures are small to medium in size, growing up to 8 inches long. Interestingly, Trinity River turtles have been documented as even smaller than their regional counterparts. Some herpetologists surmise this could be due to temperature suppression caused by elevated dam releases causing cold water releases in the latter spring and summer months (6). Watch Don Ashton’s 2024 Trinity River Restoration Program Science Symposium presentation on the subject below.

Don Ashton, Senior Aquatic Herpetologist/Ecologist for McBain Associates/Applied River Sciences presents, “Frogs and Turtles informing flow management and river restoration.” at the 2024 Trinity River Restoration Program Science Symposium.

Their dark brown or olive-colored shells often feature fine, lighter markings that give them a marbled look as reflected in their species name, marmorata.  Their low profile and coloring help them blend in with riverbanks, keeping them safe from predators like raccoons, skunks, and birds of prey. The male northwestern pond turtle can be identified with a pointier snout and lighter pale cream coloring under its neck. If you encounter a turtle with hints of red near the ear it is likely a non-invasive red-eared slider, make note of where you are and if possible, provide photo documentation to the Trinity River Restoration Program or the California Department of Fish and Wildlife. Documentation of these instances can help in protecting our native turtle populations.

image
A female northwestern pond turtle on the Southfork Trinity River. [Garth Hodgson, Don Ashton]
Adult male northwestern pond turtle. [Don Ashton]
A red-eared slider. [wikimedia commons]

image

Unlike many reptiles, northwestern pond turtles grow slowly. They start out about the size of a quarter. Females don’t start laying eggs until they’re between 8-10 years old (3, 7, 8). They lay between 3 and 13 eggs, which incubate through the summer. In some parts of Northern California, hatchlings stay in the nest through winter, emerging the following spring. In the photo you can see a comparison of a female turtle at 55 years old with a newly hatched turtle. Ashton, in the background mentioned that the elder at age 55 was carrying 9 eggs at the time of that photo (2018) which suggests their lifespan may be quite long. Ashton mentioned, “it is certainly possible that there are turtles living in the mainstem that have lived there since before the dam was placed.”

Photo: A female, marked and recaptured and aged at 55 years old in comparison with a hatchling. Held by Bruce Bury and Don Ashton smiles from the back in 2018. [Jamie Bettaso]

The northwestern pond turtle has been studied locally for over 50 years due to the diligence of herpetologist Bruce Bury, now retired from USGS, who monitored northwestern pond turtles starting in 1968 while earning his Ph.D. at UC Berkeley. He marked turtles with an identifying notch in a tributary of the South Fork Trinity River, allowing for scientists to track longevity on the only native species known in the Klamath Range (5, p. 354). Although Bury has documented turtles over 50 years old, northwestern pond turtle longevity is still being studied today.

The northwestern pond turtle is commonly seen in the Trinity River, but its population has been declining throughout its west coast range. This decline is so severe that in 2023 the U.S. Fish and Wildlife Service proposed to list the northwestern pond turtle as a “Threatened” species (8, 11). Habitat loss, hydrologic alterations and invasive species are a few human caused threats to northwestern pond turtles. The state of California also recognizes the northwestern pond turtle as a species of “special concern”. As such, handling these turtles requires permitting and are considered illegal to keep as pets.

The Trinity River Restoration Program has been involved in research to identify and address some of these threats. A graduate student from Cal Poly Humboldt, Leah Sloan, determined that non-native bullfrogs (Lithobates catesbeianus) eat young northwestern pond turtle hatchlings to the detriment of their populations along the Trinity River (10). Bullfrogs prefer off-channel ponds, which are perfect areas for northwestern pond turtles to grow. Bullfrogs require perennial ponds to reproduce because their tadpoles take longer than one year to grow (and the mainstem Trinity River is too cold and swift to support bullfrogs year-round), so ponds that normally dry out won’t support bullfrogs permanently. Seasonal drying isn’t much of a concern to turtles because they can simply walk to the river when their home dries up. This is one recommendation for the Program to consider when rehabilitating a site.

A trail camera captures a female northwestern pond turtle basking on a log. [Don Ashton]

Today, turtle researchers and wildlife managers are still learning more about turtle behaviors and how to change management to better serve the northwestern pond turtle in the Trinity River region. From size and aging to nesting sites and travel patterns, each discovery helps build a clearer picture of what these turtles need to thrive.

References

  1. Scientific and Common Names of the Reptiles and Amphibians of North America – Explained © Ellin Beltz
  2. Holland DC. 1994. The Western Pond Turtle: Habitat and History.
  3. Bury, R.B., Welsh, H.H., Germano, D.J., and Ashton, D.T. (eds). 2012. Western Pond Turtle: Biology, Sampling Techniques, Inventory and Monitoring, Conservation, and Management. Society for Northwestern Vertebrate Biology, Northwest Fauna, Number 7. 128 pp. 
  4. Shaffer H.B., Scott, P.A., 2019. Assessment for the Western Pond Turtle. Prepared for the US Fish and Wildlife Service by University of California, Los Angeles.
  5. Kauffmann, M. Garwood, J. The Klamath Mountains: a Natural History. 2022. p. 353-354.
  6. Ashton, Don & Bettaso, Jamie & Welsh, Hartwell. (2015). Changes across a Decade in Size, Growth, and Body Condition of Western Pond Turtle (Actinemys marmorata) Populations on Free-flowing and Regulated Forks of the Trinity River in Northwest California. Copeia. volume 103. 621-633. 10.1643/CP-15-253.
  7. California Herps – Northwestern Pond Turtle – Actinemys marmorata
  8. Wikipedia – Western Pond Turtle
  9. https://www.fws.gov/press-release/2023-09/us-fish-and-wildlife-service-proposes-federal-protections-both-species
  10. Sloan L, Marks S. 2012. Summary of Management Implications for the Project on Western Pond Turtles (Actinemys marmorata) in Lentic Habitats Along the Trinity River, California. Report to the U.S. Bureau of Reclamation, Trinity River Restoration Program, from Humboldt State University, Department of Biological Sciences, Arcata, CA. Available: https://www.trrp.net/library/document?id=1819.
  11. Endangered and Threatened Species: Status with Section 4(d) Rule for the Northwestern Pond Turtle and Southwestern Pond Turtle. Posted by the Fish and Wildlife Service. Apr 4, 2024.
Return to the May Newsletter

Featured Article – APR25

Posted on by

Fish Biologists Turned Farmers: Growing Food for Juvenile Salmonids in a Regulated River System

Scientists measure flow at a benthic macroinvertebrate sample site on the Trinity River this March. [Kiana Abel, Trinity River Restoration Program]

Modern river science related to salmon restoration is everchanging due to the complex interplay of factors affecting their life cycle. There are man-made issues including habitat degradation, barriers to migration, harvest; as well as environmental, such as climate change, and ocean conditions. This makes it difficult to isolate and address specific issues as they are all interconnected. There is also intricacy in finding patterns to mimic regarding the complexity of change that our system presents us from year to year (think wet year vs dry year).

For many years river restorationists followed the mantra of “if you build it, they will come” thus resulting in habitat reconstruction efforts along identified areas within the 40-mile Trinity River Restoration Reach. This combined with increased releases from Lewiston Dam (starting in the year 2004) are thought to have led to the doubling of natural origin juvenile Chinook Salmon populations in the Trinity River (Pinnix et al 2022).  

 

Even though we have seen a doubling of juvenile Chinook Salmon outmigrants from the Trinity River, adult returns remain lower than in the past. A decline of adult Chinook Salmon returns along the entire West Coast indicates there may be other issues than just in the rivers alone. Chinook Salmon have many limiting factors to survival and the Program can significantly influence only a portion of the Chinook Salmon’s life history – the riverine stages (returning adults to juvenile outmigration). Trinity River ecologists have been evaluating changes to restoration techniques to understand how to produce more robust juvenile salmon, and hopefully more returning adults, within the limited area and timeframe they inhabit the mainstem Trinity River.

One clue from decades long data collection is that the juveniles, although more in quantity, are smaller now than in the past– leading to the indication that growth rates might be inhibited during their rearing period. This indication has led program scientists to conduct a multi-year monitoring effort aimed at shedding a more definitive light on how food sources for juvenile salmonids interact with flow, temperature, scouring floods, and floodplain inundation on the Trinity River.

Until recent management changes, Lewiston Dam, was not managed to release variable flows that mimicked pre dam flows during the winter months. The lack of variation and flow has prevented several ecological processes, like scouring floods and floodplain inundation, and these seasonal floods build and break down algae which feed benthic macroinvertebrate communities which are the food supply for young salmon when they hatch and emerge from gravels.

Read on to explore the significance of algae, and the fish food within (benthic macroinvertebrates) alongside key functions of scour and inundation and how these important functions build the foodscape to aid juvenile salmonids within the Trinity River.

Trinity River Juvenile Salmonids

Juvenile Chinook Salmon. [Ken DeCamp]

Salmonids are a keystone species meaning their presence and activity have a disproportionately large impact on their ecosystem. Juveniles specifically play a crucial role in ecosystem health by serving as food for various predators in the river system, including other fish, birds, and mammals.  As they grow into adults salmon are critical to support recreational, commercial and Tribal harvest as well as delivering important marine derived nutrients from the ocean back to inland ecosystems. 

Trinity River salmonids that are native to our watershed each have unique life histories as well as habitat needs within the river system. Due to their cultural, economic and environmental influence the three native species of interest to the Program are Steelhead (Oncorhynchus mykiss), Coho Salmon (O. kisutch), and Chinook Salmon (O. tshawytscha). There are also two additional native anadromous species to the Trinity that have specific cultural and ecological significance; the Pacific Lamprey (Entosphenus tridentatus) and the Green Sturgeon (Acipenser medirostris).  

Despite unique habitat needs these species do share common life-history requirements that are considered when making decisions regarding restoration of the fisheries. At the juvenile stage these requirements include;

  1. Sediment vital in just the right amount. Spawning gravel that has a low amount of fine sediment helps water flow through the spaces between the eggs, which increases the chances of eggs hatching and young fish survival. However, too much sand and silt can suffocate both the eggs and fry, making it harder for the young fish to emerge successfully.
  2. Diversity in temperature and flow. When digesting they require low-velocity, shallow habitats that provide temperatures for prime digestion. As they grow, a variety of habitat types are required that include faster, deeper water and instream cover;
  3. Overwintering habitat. Coho salmon and steelhead must have abundant overwintering habitat composed of low-velocity pools and interstitial cobble spaces; and
  4. Food availability. abundant food sources can increase their chances of survival during their migration to the ocean and ultimately, as adults, to return to spawn. 

Regulated river systems, shaped by dams, levees, and other infrastructure, significantly disrupt the natural processes that support juvenile salmonids. Most significantly, habitat availability below a dam is limited by the loss of natural processes of rivers.  Thus, the Program has been given five main tools to mitigate for the presence of the dam. Flow Management, Channel Rehabilitation, Sediment & Wood Augmentation, Watershed Restoration, and finally Adaptive Management.

The Trinity River Restoration Program utilizes channel rehabilitation to return low floodplain habitat to the river and its aquatic species. In recent rehabilitation projects like Oregon Gulch, the designs are intended to follow the Stage 0 restoration concept. Stage 0 restoration is a method for restoring rivers that focuses on resetting the river to allow natural processes to shape the landscape. The goal is to recreate environments where river processes can improve connections within the ecosystem. This approach helps create vibrant and self-regulating riparian and stream areas that can develop on their own over time.

The Program also utilizes variable flow management to help shape habitat. Until recently due to forecast methods and limited data, variability was only utilized during one season, the snow-melt peak and recession period (April through June, July and in wetter years into August). In water years 2023 and 2025 Program partners came to agreement that changing variability by reallocating water to key growth periods during the late winter and early spring months could help juvenile salmon become more robust.

Scour and Inundation: Key to River Function in Mediterranean River Systems

Scouring floods and floodplain inundation are two important river processes influenced by river releases. Scour and inundation’s ability to support young salmon rely heavily on the physical structure of the Trinity River.

Dr. Eric Peterson, Science Coordinator for the Trinity River Restoration Program, talks about the important ecological function of scour. Scour is a process in river systems that builds a rivers shape by rolling rocks and resets algae and bug populations.

Scour occurs during large winter storms when fast-moving water erodes the riverbed, moving sediments and changing the channel’s structure. This process helps to maintain river functions by exposing and transporting sediments, logs, and nutrients throughout the river system. Combined with flow, these elements contribute to a dynamic river design and are crucial for all life stages of salmon. Logs and sticks create hiding spots from predators and provide areas with optimal flow conditions for feeding. Deep scoured holes provide temperature diversity throughout the year. The movement of sediments and other detritus transfer nutrients to floodplains which provides a suitable substrate for algae and benthic-macroinvertebrate populations.

Chris Laskodi, Fish Biologist for the Yurok Tribe discusses the ecological function of inundation and drift for young salmon and the foods they eat during the winter months when rivers are swollen with water.

Inundation refers to the seasonal flooding of riverbanks and adjacent floodplain habitats during higher flows during the spring. This flooding is vital for rejuvenating riparian zones and promoting the growth of riparian vegetation. Inundated areas often serve as nurseries for juvenile salmonids, providing preferred temperatures for digestion and shelter from faster areas of higher flow within the main channel. The nutrients deposited during flooding can enhance algal and macroinvertebrate production, further supporting the growth of juvenile salmonids.

The Role of Algae & Benthic Macro Invertebrates in Juvenile Salmonid Success

Algae play a significant role in primary productivity, providing essential food sources for various aquatic organisms, including benthic macroinvertebrates, the favored food of out-migrating juvenile salmonids. Through photosynthesis, algae contribute to oxygen production, an essential requirement for many aquatic species. Additionally, algae facilitate nutrient cycling within the ecosystem helping to enhance habitat health.

Read more about Trinity River Algae, Food Webs, and Flows

image

Benthic macroinvertebrates are tiny invertebrates that live on the riverbed. While young salmon feed on both terrestrial and aquatic invertebrates, these organisms provide an essential source of food for juvenile salmonids. Common examples of benthic macroinvertebrates that juvenile salmon consume include mayflies, stoneflies, midges, and caddisflies. Moreover, these organisms serve as indicators of ecosystem health; their presence, diversity, and abundance can offer valuable insights into the ecological status of a river system. In addition to being food for juvenile fish, benthic macroinvertebrates contribute to the breakdown of organic matter, aiding nutrient cycling and improving overall ecosystem productivity.

Read more about Trinity River Benthic Macroinvertebrates

Understanding the roles of algae, benthic macroinvertebrates, scour, and inundation in the Trinity River, a regulated river system, is essential for supporting juvenile salmonids. By recognizing the interconnectedness of these organisms and processes, ecologists can implement strategies that potentially promote a balanced ecosystem. Ensuring that algae and macroinvertebrate populations meet the demand of juvenile salmonids will enhance their health and survival contributing to the overall vitality of aquatic ecosystems.

Return to the April Newsletter

TMC – Mar25

Posted on by

Summary of the Trinity Management Council’s March Quarterly Meeting

TMC Partnership Ring
TMC Partnership Ring

The Trinity Management Council met virtually on Wed., March 19, 9am-3pm for its spring-quarter meeting. There were seven major topics on the agenda along with two decision items.

Program Updates (TRRP Staff)

Trinity River Restoration Program Executive Director, Mike Dixon highlighted a busy quarter for channel rehabilitation, including excavation work at Upper Connor Creek and at Sawmill, gravel processing along with vegetation clearing in preparation for summer rehabilitation. Staffing updates revealed that no staff accepted the deferred resignation offer, and new secretary Samantha Maier has joined the team, while efforts to fill the vacant Data Steward position have been complicated by a hiring freeze. The report also noted that the Program received a continuing resolution for the budget, but there are concerns about not receiving the full requested funding for FY26. Data calls have increased, requiring justifications for agreements, and communication from higher authorities has been limited. The budget update indicated a lean spending plan with minor changes, including reduced travel costs and a new environmental support services contract that is higher than the previous one. Additionally, funding from the IIJA (formerly BIL) has been secured for ecosystem restoration projects, although some funds for revegetation and invasive weed treatments have been lost.

James Lee, Implementation Branch Chief highlighted that the branch will be prioritizing remaining restoration sites and preparing draft reports for Upper and Lower Rush Creek and the Hatchery reach submitted by the Yurok Tribe, while considering a potential project at Reading Creek, pending landowner permissions. Active watershed projects include planned work on Weaver Creek, with a funding agreement in progress, and the East Branch East Weaver Creek culvert removal, which is funded and awaiting cultural clearance. The East Weaver Creek Dam has been removed, with funds potentially redirected to the Salt Creek project or Connor Creek improvements. The Salt Creek Channel rehabilitation project is funded and undergoing a scour analysis before earthwork begins, while the upper Hayfork Creek watershed assessment is also ongoing and funded, supporting regional restoration efforts.

Kiana Abel, Public Affairs Specialist updated attendees on public outreach efforts of the last quarter, including the publication of three newsletters along with successful community events like Science on Tap and birding days. The team is planning several upcoming events, including Earth Day activities. Kiana provided a summary of the yearly Trinity River survey which revealed increased community participation and demographic shifts.

The science report highlighted key updates, including spring flow scheduling’s relationship with winter flow variability and reservoir management releases. Progress on the limiting factors analysis is strong, following a productive meeting with the contractor to identify necessary data. Partners are expected to provide quality-controlled datasets in the coming months. The Science Advisory Board has also engaged with this topic, offering valuable feedback. Additionally, the fiscal year 2026 science priorities are being developed, with two proposals received from a January request for proposals, focusing on a food module for S3 and the biological response of northwestern pond turtles to thermal diversity, while a topic on sedimentation impacts was omitted. These proposals are under review, with plans to present finalized topics to the Trinity Management Council at the June meeting.

Central Valley Operations Update (Elizabeth Hadley, Reclamation)

Northern California Area Office, Elizabeth Hadley shared operational updates regarding Central Valley Operations. The March forecast from CVO is projected to indicate nearly full reservoirs this year although not expected to spill through the glory hole. The Carr Tunnel repair is scheduled for completion at the end of March. Current repairs are reducing the likelihood of future outages for another six years.

Budget challenges were discussed, with delays in approvals for purchases affecting overall operations. While the TRRP staff did not lose any members during recent cuts, the NCAO office experienced significant losses, including 11 retirements and the loss then rehiring of 6 probationary employees. The value planning study for the Trinity Dam has been delayed due to staffing issues and frozen funding, with hopes to start in May, though further delays may occur.

An update on the Trinity River Hatchery modernization project was provided, noting that two tasks related to environmental justice have been removed from the service contract to comply with Executive Order 14173, which aims to end illegal discrimination and restore merit-based opportunities. The overall modernization schedule includes the award of the design-build contract, expected in Oct. 2025. NEPA requirements are to be completed by Oct. 2026, construction is set to begin in the first quarter of FY27, and the project is anticipated to be completed by the end of 2028, with a full closeout and transfer back to operations and maintenance by the end of 2029.

Post-TAMWG public outreach options (Ty Wallin, US Fish and Wildlife)

Ty Wallin, US Fish and Wildlife presented on options for engaging public input following the dissolution of the Trinity Adaptive Management Work Group (TAMWG), focusing on compliance with the Federal Advisory Committee Act. The TAMWG, which provided diverse viewpoints on the Trinity River Restoration Program, was terminated in 2019, the Program began the reinstatement process but are currently not clear if the administration would support the formation of an advisory committee. Wallin emphasized that while Federal Advisory Committee Act applies to formal advisory groups, there is flexibility in engaging the public through informal meetings that gather personal viewpoints without requiring consensus advice. Suggestions included leveraging community organizations like the Resource Conservation District (RCD) to facilitate discussions. The Program and TMC support the collaboration, if the RCD can facilitate in the future.

Communications Workgroup Charter – Decision Item (Kiana Abel, TRRP)

Kiana Abel, Public Affairs Specialist for the TRRP presented a draft Communications Work Group Charter which was developed by nominated members of the various TMC partnership. The TMC was asked decide to vote in a Communications Work Group to be added into the TRRP Technical Work Group framework. The workgroup would specifically aim to improve collaboration among partner agencies with the intent of better informing the public.

The draft charter was discussed, outlining the group’s purpose to develop an annual communications plan and provide recommendations for effective public relations. Key objectives include communicating scientific activities, evaluating messaging strategies, contributing to the annual communications plan, ensuring consistent science communication, and assisting in the creation of various communication assets. The proposed annual work plan suggests meeting quarterly to prepare for IDT/TMC meetings, focusing on analytics and communication tactics, and conducting a SWOT analysis to assess progress.

The session concluded with an invitation for questions and discussion on the proposed motion for the workgroup. After lunch, the TMC voted to form the Work Group 7 in favor and 1 partner absent. The TMC also elected to fully review and suggest edits to the draft charter to be voted on at the next TMC monthly meeting in April.

Hatchery Technical Team Update (Chris Laskodi, Yurok Tribe)

Chris Laskodi, Fish Biologist for the Yurok Tribe provided a Hatchery Technical Team (HTT) update. It was noted that the group, which has been meeting quarterly since around 2019 aims to improve collaboration among Trinity River Restoration Program (TRRP) staff regarding hatchery operations. The HTT is creating a document to outline the intricacies of hatchery operations and their interactions with TRRP actions, such as flow requirements for fish releases.

Key updates from the HTT include the lifting of the funding freeze for hatchery modernization, with a design and build solicitation expected by the end of April, and the delivery of a new fish trailer for automated fish tagging. Additionally, a temporary fix to a fish exclusion gate at the Lewiston powerhouse is anticipated to enhance flow variability for salmon.

The hatchery spawning season recently concluded, with production goals for spring and fall Chinook slightly below target, while Coho and steelhead met their goals. The Hoopa Valley Tribe is raising 100,000 Coho eggs for local release, and all Coho from the hatchery will now be double-marked for better tracking. The HTT is also implementing a hatchery genetic management plan, focusing on carcass supplementation and broodstock collection, with a record number of natural origin Coho transported to the hatchery this year. The team continues to develop metrics for Coho introductions to align with management plan requirements.

TRD Re-Consultation Update (Kristin Hiatt, Reclamation)

Kristen Hiatt, Natural Resource Specialist at Reclamation’s Bay Delta office, provided an update on the re-initiation of consultation for the long-term operations of the Central Valley Project (CVP) and State Water Project (SWP), including the Trinity River division. She summarized the progress of the National Environmental Policy Act (NEPA) and Endangered Species Act (ESA) processes, noting that all steps have been completed, culminating in the publication of the record of decision on Dec. 20, 2024. Following the administration transition, a new executive order was issued to improve water resource management in California. Hiatt highlighted ongoing collaboration with joint leads on the Trinity River Division, including technical meetings and the development of technical appendices for resource analysis. The consultation schedule was updated, with alternatives development expected to progress into an interim draft phase by spring 2025. The next quarterly meeting is scheduled for June, with further information available on Reclamation’s Bay Delta Office website.

Spring hydrograph decision – Decision Item (Patrick Flynn, Trinity County)

Patrick Flynn, Flow Work Group Coordinator, presented the water year 2025 spring flow recommendations. He outlined the flow planning process, emphasizing the unique circumstances of water year 2025, particularly the full implementation of the winter flow variability project and reservoir storage management releases. Flynn recapped the winter flow project timelines and discussed the scenarios considered for water year planning, noting that the March B120 forecast indicated a “wet” year.

Flynn presented developed hydrographs for the spring release which focused on riparian and geomorphic objectives, using Decision Support System (DSS) results to guide their recommendations. The recommended hydrographs are B (geomorphic and fish-focused) for a “wet” year and D for an “extremely wet” year, as they showed greater benefits for smolt production and Chinook salmon biomass. A concern was raised regarding the timing of two peaks in July intended to signal spring Chinook migration, with potential safety risks for recreational users. Flynn suggested the TMC discuss this issue and decide whether to keep the peak on July 4 or move it to July 8. He concluded by inviting questions and offering to revisit any specific slides for clarification.

The TMC voted (7-1) in favor of adopting the recommended hydrograph B “wet” year and hydrograph D ” extremely wet” year with a shift to schedule the two latter peaks from July 4 to July 8.

Return to the April Newsletter

Plant Spotlight – Horsetail (Equisetum arvense)

Posted on by
image

Equisetum is a group of plants categorized as a fern that are often found in wet places. It superficially blends into the “grass-like” background of a wetland around rivers or marshes. This group is otherwise often called horsetails with 15 species found worldwide. There are four species most commonly found in the Klamath Mountains including Equisetum arvense (common or field horsetail) which happens to be the most common horsetail in the world.

In 1883 a prominent plant taxonomist, August W. Eichler, divided the plant kingdom into two groups: Phanerogamae which reproduce by seed (via flower or cone) and Cryptogramae which reproduce via spore. The Klamath Mountains have an incredibly diverse existence of terrestrial cryptograms, which are represented by mosses, liverworts, lichens, ferns, forest mushrooms and algae [1]. As you may have deduced from the list, moisture plays a key roll for reproduction of a cryptogram. Classified within the fern family, the horsetail arrived on earth approximately 375 million years ago. The modern genus, Equisetum is a “living fossil” of the subclass Equisetaceae, which for 100 million years dominated the understory of Paleozoic forests [2]. The ancient genus ranged from large trees to the more modern low lying species we commonly see today.

For perspective, current evolution of hominids is understood to have occurred 55 million years ago, so our oldest hominid relatives likely also interacted with this plant. Features from this group are considered to be the early origins of plants known as “vascular” plants, which have cells specialized for holding water and minerals and moving them up and down through the ‘body’ of the plant.

image

Functionally, Equisetum is rhizomatous – meaning it has more than one way of reproducing. Sideways roots spread the same plant horizontally in the ground in addition to the little spore-bearing “cones” (strobili) which allow it a mechanism for sexual reproduction.

Most commonly you’ll see the plant spread, or propagate, along the river by being scoured out of the ground by high flows and wadded up with leaves, wood, and sediment deposited along the river bar. This is a natural process for plants to establish along depositional areas (sediment accumulation areas) freshly created along the banks of a dynamic river.

Reproductive spores of E. arvense have four ribbon-like appendages sensible to moisture. These “legs” fold back around the main body in humid air and deploy upon drying. Check out a video of this process below!

image

The sections of the plant are jointed and clasping each-other with little “frills” which are the true leaves of the plant. Find these leaves at the many joints which make up the stem. These little joints can be popped apart and the inside is rough, hollow and crunchy. The interior of the stems are made up of strong, lengthwise ridges that have been documented as being useful to scour materials like arrows, as well as polish metals and musical instruments [2].

Photo: Equisetum found along the Trinity River. [Simone Groves, Hoopa Valley Tribal Fisheries]

image
Check out the fine sediment collecting along the rough “skin” of the Horsetail patches along the edges of the river, and this scour zone along the edge of a thick patch in a side channel of the river. [Simone Groves, Hoopa Valley Tribal Fisheries]

I first began deepening my relationship with this plant when I worked on a farm and met a gentleman there who spoke only Spanish (no English) and when we discussed the name for the plant, he called it by the direct translation of the common name that I knew for it “horse-tail” which is “cola de caballo” in Spanish. This piqued my curiosity as it seems like the common name is a unifying force. The Latin name is also derived from the same meaning “equus” (horse) and “seta” (bristle) and the term equisetum has been known to be used since the 15th century.

This plant is known in herbalism as an “archaeological vestige” of times immemorial. Indigenous uses are documented throughout the farthest reaches of land on our earth, including the northernmost tip of Greenland and Alaska, down to the southern tip of Argentina and Chile and the African continent as well. It can be found on islands completely isolated from the main land masses. It’s a pretty amazing feat in the plant world to have such a dynamic habit to survive under such varying conditions!

This plant has been catalogued by all of the first naturalists and medics attempting to collect together the resources of plant knowledge for indigenous plant use of early Europe including, Pliny the Elder in his book Naturalis Historia-Natural History. It is agreed upon that this plant can be consumed to help with hemorrhages, dysentery, diuresis, respiratory clarity, and internal cuts and hernias. It is also thought that the juices can be a good eye medicine for sore eyes, and some tribes have used it for treating fevers. The astringent qualities of the plant are thought to constrict tissues and provoke elimination of liquid. A total of 229 chemical compounds are isolated from the plant and used in contemporary medicines. Additionally, the silica in the body of the plant is a great, gentle exfoliant for your skin, or for washing dishes while camping.

Sometimes this plant group can be found as a common weed in your garden. Usually, when you see this plant, it’s an indicator of compacted, and anaerobic (lacking-oxygen) soil conditions. This can happen due to compaction from roads, or due to water-logged conditions, or where water is pooling for long periods of time. Water displaces oxygen by filling up the holes or pores in the soil and this makes it hard for plant roots to ‘breathe.’ Equisetum has a specialized cell type called ‘aerenchyma’ which are separate cells in the plant body for storing oxygen. This helps the plant be able to metabolize even when there’s no air.

Another unique characteristic of the Horsetail group is the silica mineral content in the plant body. Among all terrestrial plants, only horsetails require silicon as an essential mineral nutrient. Silica or silicon dioxide (SiO2) might be familiar to you as an important part of sand and crystalline quartz. Silica is an essential component of bones and organs and cartilage in human bodies. Water-born silica is the best way for various forms of biology to uptake silica and use it. Equisetum is the perfect plant to perform this function in the landscape.

For those interested in creating natural fertilizers for your garden, Equisetum has some surprises. Korean Natural Farming is a technique for amplifying native micro-organisms (bacteria, fungi, nematodes, and protozoa) to increase soil fertility. One Korean Natural Farming technique is to create a Fermented Plant Juice by breaking up plant material and allowing them to ferment. How can you make your own silicate rich fertilizer in your own back yard? In my personal experience it takes about 1 week for your fertilizer to be ready, and it is best to use Equisetum during it’s peak growing season, from April to July. Break up pieces of horsetail and place it in a bucket, or container, ¼ full is plenty of material to be effective, and fill it up with water. Let this bucket sit for 5-10 days (depending on temperature) and when you see bubbles appear in the water, it’s ready. Sugar can be added to increase the “vigor” of the ferment. When you see bubbles, the water can be poured on your garden. This water also smells remarkably like horse manure! Which has led me to question the multiple origins of the etymology of its common name.

References

  1. Garwood, J., Kauffmann, M. The Klamath Mountains A Natural History. Backcountry Press. First Edition. 2022. Pg. 167.
  2. Equisetum. Wikipedia The Free Encyclopedia [Equisetum – Wikipedia]
  3. Native American Ethnobotany Database. Equisetum arvense L., [http://naeb.brit.org/uses/species/1421/]
  4. Online Etymology dictionary
  5. equisetum observations on iNaturalist
  6. American Herbal Products Association
  7. Sureshkumar, J., et al. Genus Equisetum l: Taxonomy, Toxicology, Phytochemistry and Pharmacology. Journal of Ethnopharmacology, Elsevier, 18 May 2023.
  8. Kundu, S. et al. Evidence of the oldest extant vascular plant (horsetails) from the Indian Cenozoic. Science Direct Plant Diversity. September 2023
  9. Cho’s Global Natural Farming
  10. KR;, Martin. The Chemistry of Silica and Its Potential Health Benefits. The Journal of Nutrition, Health & Aging, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/17435951/. Accessed 10 Apr. 2025.

Simone Groves, Riparian Ecologist, Hoopa Valley Tribal Fisheries

Simone is first generation California transplant of scottish descent raised in the unceded territories of the Raymatush in the rural west peninsula of the SF Bay where farmers, farm workers and hippies form the heart of the small town. She graduated in 2016 from Humboldt State University with a BS in Botany and has worked in the outskirts of rural Humboldt county on Natural Resource and Land management since 2013. She is passionate about plants and their interactions with dynamic systems as a mechanism for relearning our human-landscape interdependence.

Return to the April Newsletter

Featured Article – 2024 ED Report

Posted on by
image
Interpretive sign design that sits off of Sky Ranch Road overlooking the Oregon Gulch Restoration Project, which finished and placed in FY2024. [Kiana Abel, Trinity River Restoration Program]

The Trinity River Restoration Program’s twenty-fourth year brought challenges and positive steps forward with agency collaborations, channel rehabilitation on the Trinity River, watershed restoration and environmental flow management. 

Implementation Branch

In 2024 the Trinity River Restoration Program Implementation Branch acquired the training and licensure to fly a drone within the Trinity River watershed to better inform restoration practices and the community through aerial imagery.  Small Unmanned Aerial Systems, also known as drones, are becoming a common place and vital tool for natural resource managers across the country. Drones provide a nimble, cost effective, easy to employ tool for collecting aerial photography and an array of topographic data. 

In collaboration with agency partners and local landowners, the Program’s Implementation Branch completed the first phase of a two-year channel rehabilitation project in Junction City, Ca., the Upper Conner Creek Rehabilitation site.  Crews restored 9.3 acres of riparian habitat, mulched and seeded upland areas, replanted riparian zones, added channel complexity and returned much needed low-flow habitat to juvenile Trinity River salmonids. The second phase of the project, to be completed in 2025, will further enhance habitat and recreational facilities for river enthusiasts in the area. 

Upper Conner Creek Restoration Site shown in comparison of pre (left) and post (right) Phase I restoration via aerial photography. [Ken DeCamp, 2019 (left), Elliot Sarnacki, 2024 (right)].

Science Branch

The Program facilitated it’s first in-person Science Symposium since 2016 in Weaverville, CA. The four-day event covered presentations on fish populations; habitat, flow and temperature; and the physical channel form. Nineteen scientists from around the world with specialties in geomorphology, hydrology, biology, and ecology gave presentations throughout event discussing their mutual impact toward management actions with the mission of restoring anadromous populations of Chinook Salmon, Coho Salmon, and Steelhead. The presentations were recorded with the help of the California Great Basin Public Affairs team and are available by clicking to this page: Science Symposium.

 In December, despite initial disagreement on changes to flow management, all 8 partners came to agreement to adjust the timing of flow thus providing the Trinity River a schedule of water releases to better match the needs of rearing juvenile salmonids for water year 2025. This includes the Program’s first ever synchronized storm pulse flow, which occurred with a Dec. 23 storm event. 

In recent years, scientists across the Trinity River Restoration Program’s partnership have recognized that program actions have more than doubled production of juvenile Chinook in the Trinity River, yet those increases have not translated into larger runs of adult Chinook.  Efforts in the 1990’s identified only a single limiting factor: juvenile habitat.  It is now apparent that Chinook have additional limiting factors which may, or may not, be controllable by the Program.  The science branch has engaged a contractor (Cramer Fish Sciences) to develop a new Limiting Factors Analysis (and to provide an independent evaluation of limiting factors).  The process is underway and will examine all life stages including when Chinook are in the Klamath River, estuary, and the Pacific Ocean.

2024 Funding Sources

image

Allocations were received from two funds within the Bureau of Reclamation in Fiscal Year 2024 totaling 86.6% of the Program’s funding source. Additionally, the U.S. Fish and Wildlife Service provided funds for 3.1% of the total budget. Both organizations are administrators of the Trinity River Restoration Program and serve as agencies in the Department of the Interior for the United States Government. An additional 10.4% of funding came from the Infrastructure Investment and Jobs Act for the Upper Conner Creek Project.

The fiscal year 2024 budget allocations went to three primary areas as shown in Figure 4 (right).

Funding supported physical modifications to the river and the associated modeling, designing, permitting, and monitoring of physical and biological responses. Other partner agencies were funded and/or contributed in-kind services to support Trinity River Restoration Program activities. It should be noted that staff positions and agency assistance funding can shift between categories so the levels of funding in Administration, Implementation, and Science are not directly comparable between years.

Thank you to all of the staff across our partnership who have made this year so successful. Here’s to an even better 2025.

Mike Dixon, Trinity River Restoration Program Executive Director

Additional Accomplishments

Watershed Grantee Funding

The Program awarded $659,900 in fiscal year 2024 to two projects within the Trinity watershed. The grantees put forward $2,056,600 in matching funds for a total conservation impact of $2,716,500. The projects selected will improve aquatic habitat by reducing fine sediment delivery, improving fish passage, and pursuing increases to tributary flows in the dry season in tributaries of the Trinity River. We congratulate the grantees and are excited to see the outcome of each project. Please read below to learn about each grantee, proposal and award amounts.

Salt Creek Floodplain Restoration Project (CA)
Grantee: Watershed Research and Training Center
Grant Amount: . . . . . . . . . . . . . . . . . . . . . $470,900
Matching Funds: . . . . . . . . . . . . . . . . .   $2,026,600
Total Project Amount: . . . . . . . . . . . .     $2,497,500

This project is granted to improve 2,000 feet of heavily degraded salmonid habitat along Salt Creek, a South Fork Trinity River tributary, by reconnecting the creek to its historic floodplain using engineered and process-based restoration techniques. The project will increase aquifer recharge and storage for slow release to temper a thermal barrier for salmonids, restore geomorphic functions that will improve salmonid spawning gravels, create pools for summer cool water refugia, increase habitat heterogeneity for winter flow high-velocity refugia, and improve native riparian flora, all of which will increase the resilience of aquatic species from the impacts of climate change.

image

Upper Hayfork Creek Assessment and Planning Project (CA)
Grantee: Watershed Research and Training Center
Grant Amount: . . . . . . . . . . . . . . .  $189,000
Matching Funds: . . . . . . . . . . . . . .   $30,000
Total Project Amount: . . . . . . . . .  $219,000

The Upper Hayfork Creek Assessment and Planning Project will assess over 17 stream miles and 700 floodplain acres within the upper Hayfork Creek watershed, a major tributary to the South fork Trinity River in California. The project goal is to identify restoration opportunities for the purpose of improving salmonid habitat quality and quantity. The Project will utilize GIS and LiDAR analyses, field measurements of salmonid presence and habitat characterization, and a comparison of ecological flow needs with water availability. The outcome of the Project will be one Restoration Assessment and Planning document presenting analysis, field data collection, and outreach results with a priority list of restoration projects and one restoration design to advance toward implementation.

In addition to the two new watershed projects mentioned above, one project that was granted Program funding was completed in 2024. Read below for the project accomplishments.

In September last year an opportunity to complete Phase I at the Indian Creek tributary restoration project arose from budgetary savings in FY24 and was approved by the Trinity Management Council by vote at the September quarterly meeting. While most of the project had been restored in 2021, a key upper portion of the Environmental Study Limit was omitted during restoration due to an active mining claim on BLM land. With the mining claim lapsed, the Program was presented with a narrow window to complete the stage zero project as it was originally designed.

After approval to allocate excess funds to the project, the Yurok Tribe Construction Corporation made quick work of leveling the highly degraded channel as the stage 0 floodplain design intended. In addition large wood structures were placed to encourage habitat formation. Large boulders were harvested and repurposed to supplement existing grade control in the downstream end of the project reach. Several previously installed groundwater wells that became buried in sediment were also restored.

Final Publications and Reports

Publications and Reports

Thermal Refugia and Tributary Monitoring August and September 2021

Report for the Trinity River Restoration Program (TRRP).

Martel, C. 2023. Hoopa Valley Tribal Fisheries Department, Hoopa, California.

Available: https://www.trrp.net/library/document?id=2690

Juvenile salmonids, such as steelhead, Chinook, and coho salmon, rely on cooler water, known as thermal refugia, to survive during warm weather and low-water conditions. In 2021, a particularly dry summer in the Trinity River basin forced these young fish to seek refuge in the lower reaches of tributaries, especially on the Hoopa Valley Indian Reservation (HVIR). This reliance highlights the importance of monitoring the health of these tributaries, as drought conditions can pose serious risks to salmon populations.

To address this concern, the Hoopa Valley Tribal Fisheries Department (HVTFD) conducted regular surveys of six tributaries on the HVIR, assessing environmental conditions to ensure the habitats remain safe for juvenile salmonids. Additionally, reports indicated that adult Chinook salmon were crowding at the mouths of these tributaries, suggesting that high temperatures in the mainstem Trinity River were preventing their migration into cooler areas. Monitoring efforts are crucial for documenting and addressing any negative impacts on salmon populations.

Juvenile Survival and Migration Rate Study

Report for the Trinity River Restoration Program (TRRP).

Hoopa Valley Tribal Fisheries Department (HVTFD). 2023. HVTFD, Hoopa, California.

Available: https://www.trrp.net/library/document?id=2689

Juvenile Chinook salmon in the Trinity River tend to experience cooler temperatures and migrate later than other populations in the Klamath Basin. This delayed migration can put them at risk as they navigate through the warmer, inhospitable conditions of the lower Klamath River, which has higher disease levels. There is limited information available about how well these out-migrating fish survive as they travel from the upper Trinity River through the lower Klamath.

To better understand their survival and migration patterns, the Hoopa Valley Tribal Fisheries Department utilized juvenile salmonid acoustic tags (JSATs) in Spring 2022. These tags are designed to track juvenile salmonids as they move through river systems. Each tag emits a unique code at specified intervals, allowing researchers to monitor individual fish using submerged acoustic receivers. An array of receivers was set up along the Trinity and Klamath rivers to collect data on tagged natural and hatchery fish released near Pear Tree Gulch, facilitating the measurement of survival rates, migration speeds, and pathways taken by these juvenile salmonids.

A Method for Scheduling Lewiston Dam Releases to Mimic Diel Variations in Flow on Unregulated Streams

Report for the Trinity River Restoration Program (TRRP).

Buxton, T. H. 2024. TRRP, Weaverville, California.

Available: https://www.trrp.net/library/document?id=2648

Diel oscillations refer to the regular, periodic fluctuations that occur over a 24-hour cycle in environmental conditions, such as temperature or water discharge in streams and rivers. In streams, these oscillations can have different causes depending on the season. In winter, they often result from the melting of snow during the day, which affects how water moves through the soil and streams. From spring to fall, variations are influenced by evaporation and solar radiation. During the day, evapotranspiration can draw groundwater up to the soil surface, while at night, water in the vadose zone shifts back downslope. Additionally, evapotranspiration may tap directly into groundwater reserves during the day, with replenishment occurring at night through interactions between the stream bed and surrounding soil. Understanding these diel oscillations is crucial for comprehending ecological processes and the behavior of aquatic organisms.

Mapping Active and Exposed Coarse Bars and Fine Sediment Deposits in the Restoration Reach of the Trinity River, California

Report for the Trinity River Restoration Program.

Buxton, T. H. and J. McSloy. 2024. TRRP, Weaverville, California.

Available: https://www.trrp.net/library/document?id=2656

In summer 2023, a mapping study of coarse and fine sediment deposits was conducted on the Trinity River, specifically between Lewiston Dam and the North Fork Trinity River. The study identified a notable deficit of fine sediment, particularly upstream, demonstrating insufficient fine deposits extending up to near Steiner Flat. In contrast, coarse bar areas showed significant growth, increasing by 45% from about 1.34 million square feet in 2014 to nearly 1.96 million square feet in 2023, alongside a 30% rise in the number of bars. This growth suggests that sediment management efforts, such as gravel augmentation, can effectively mimic natural sediment supply to the river.

Coarse bars were primarily found in areas of channel expansion, bends, and reconstruction projects, while fine sediment deposits were linked to similar factors, with vegetation playing an important role as well. The primary limitation on the accumulation of fine sediment appears to be the lack of supply from Lewiston Dam downstream. To address this deficit, the addition of fine sediment near the dam and increasing channel complexity could create more suitable environments for sediment deposition. Furthermore, introducing large wood and enhancing channel roughness could facilitate the development of both fine and coarse bars.

Trinity River Restoration Program Objectives and Targets Summary

Trinity River Restoration Program (TRRP). 2024. TRRP, Weaverville, California.

Available: https://www.trrp.net/library/document?id=2654

The finalized Objectives and Targets document, approved by the Trinity Management Council in 2022, outlines refined ecological goals for the Trinity River Restoration Program. The need for this update arose from the limitations of the Integrated Assessment Plan completed over a decade ago, which encouraged the need for a more organized and streamlined set of objectives. Starting with a workshop in 2013, the process faced delays but regained momentum after the TRRP Interdisciplinary Team provided new guidance in 2018.

In early 2021, the Fish, Flow, Physical, and Riparian and Aquatic Ecology technical workgroups presented their recommendations for new objectives and targets. This document summarizes their efforts, detailing how the previous objectives were assessed and the new ones developed. While some objectives are still conceptual and pending completion, the document aims to serve as a living resource that will be updated as progress is made. It is structured into five sections: four report on each workgroup’s recommendations, and the final section outlines the next steps for prioritizing, updating, and addressing outstanding questions regarding the objectives and targets.

image

East Weaver Creek Dam Intake Relocation & Dam Removal Project & McKnight Ditch Water Conservation Project

Report for the Trinity River Restoration Program.

Five Counties Salmonid Conservation Program. Weaverville, California. 2024.

Available: https://www.trrp.net/library/document?id=2649

A Trinity River Restoration Program watershed grant helped fund two important projects to restore salmon habitats in the East Weaver Creek area. These projects returned over 2 cubic feet per second of water to flow back into it. These projects improved habitat conditions for salmonids in more than 3 miles of the creek downstream from East Weaver Creek Dam and will also reconnect 2.5 miles of habitat upstream that had been blocked.

Environmental Reports and Findings

Sediment and Wood Augmentation along the Trinity River Restoration Reach Environmental Assessment and Initial Study

U.S. Bureau of Reclamation Trinity River Restoration Program (USBR-TRRP), North Coast Regional Water Quality Control Board, and U.S. Bureau of Land Management (USBLM). 2024. July, 2024.

DOI-BLM-CA-2023-0033-EA, CGB-EA-2022-028, California State Clearinghouse No. 2008032110. USBR-TRRP, Weaverville, California.

Available: https://www.trrp.net/library/document?id=2652

The Trinity River Sediment and Wood Augmentation Project aims to enhance the river’s health by creating better habitats for salmon and steelhead fish. Developed by the U.S. Department of the Interior and its partners, the project involves strategically placing sediment and wood in the river to support spawning and rearing habitats. This initiative is informed by previous environmental assessments and recommendations established in 2011.

The project complies with the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA) to carefully evaluate its potential environmental impacts. The Trinity River Restoration Program (TRRP) will implement sediment placement at five key locations to improve the river’s ecosystem, ensuring it remains a vital resource for biodiversity and future generations.

Trinity River Variable Flow Project Environmental Assessment

Project Proponent and Lead Agency U.S. Department of the Interior Bureau of Reclamation – Trinity River Restoration Program. 2024. December 2024. CGB-ED-2024-047. USBR-TRRP, Weaverville, California.

Available: https://www.usbr.gov/mp/nepa/nepa_project_details.php?Project_ID=55082

The Trinity River Restoration Program plans to adjust water releases from Lewiston Dam to benefit salmon and steelhead fish during the winter and spring months. By shifting the timing of these releases while staying within authorized water volumes, the program aims to replicate natural river flow conditions more closely. This adjustment will help create habitats for young fish, improve conditions for their growth, and support earlier migration by providing necessary food sources and favorable environmental conditions.

The modified flows will occur in two key periods: the Flow Synchronization Period and the Elevated Baseflow Period. These changes are designed to enhance the river ecosystem by flooding rearing habitats before and during the emergence of fry, reducing cold water impacts in spring and early summer, and promoting the availability of food for juvenile fish. This project was previously recorded under tracking number CGB-EA-2024-011.

Return to the March Newsletter

Trinity River Watershed Monitoring

Posted on by

California Department of Fish and Wildlife Steelhead Report Card Dashboard

The California Department of Fish and Wildlife (CDFW) tracks steelhead angler effort and success through a reporting program. This reporting program consists of a mandatory report card that all steelhead anglers need to have in their possession while fishing. Anglers record each day that they fish, where they fish, how many fish they catch, and whether those fish are from a hatchery (determined by the lack of an adipose fin, which is removed by hatchery staff before the fish is released), or were spawned in the wild (determined by the presence of an adipose fin).

Each year, anglers are required to send these report cards back to CDFW, either physically or by entering the information online.

After many years of collecting data, CDFW recently released a compilation of raw summary data for the period of 2012-2023 (linked here). The data set can be sorted by area (the Trinity River is one of 20 river systems or regions), season, or month, and shows the numbers of fishing trips, the number of hatchery steelhead caught, and the number of wild steelhead caught.

The Klamath River and tributaries (except the Trinity River) stands out as an exceptional fishery. The Trinity River is not too far behind it among the 20 steelhead fisheries in the state.

It’s important to understand that while the raw data is informative, it is only a starting point toward understanding the fisheries. For example, in many systems, including the Trinity, hatchery production has changed substantially over the time period that the dashboard shows. Some hatcheries have reduced steelhead production by as much as 40%, which has an obvious bearing on the average number of steelhead caught per trip. Conversely, this data set covers two of the most severe droughts that Northern California has ever experienced. Droughts can leave the smaller tributary streams, which are usually off-limits to fishing because steelhead prefer to spawn in smaller streams, too dry for fish to migrate into. So, they remain in the mainstem river where people can catch them more readily than in normal or wetter years when they would have migrated into their spawning streams earlier. Tribal harvest methods, too, have changed in this time period and are much more selective for hatchery steelhead (identified by their lack of an adipose fin) over wild steelhead.

Still, this dashboard can be very useful for planning where and when to go on a steelhead fishing trip. And steelhead anglers should be happy to see the data that they carefully record and report is going to good use!

Return to the February Newsletter

The Language of Sediment

Posted on by

Rivers are dynamic ecosystems shaped by multiple interacting and overlapping physical and biological processes. A fundamental aspect of a river’s ecology is sediment, which is the foundational underpinnings of habitats, influence for water quality, and support for wildlife. In this article, we explore terminology and features of Trinity River sediments, the building blocks of our river system.

What is Sediment?

Although it might seem obvious, all sizes of rocks fit into the larger family of sediments. Sediments are inorganic particulates that can be transported by water, wind, or ice and deposited and perhaps stored for long periods of time in a particular location. In rivers, sediment is further classified according to its diameter and composition:

  • Clay (Particles smaller than 0.002 mm): Clay transports while suspended in the water column and when deposited can store nutrients aiding the growth of biology when organics chemically bind to individual clay particles.
  • Silt (Particles 0.002 mm to 0.063 mm): Silt also transports suspended in the water column and can affect light penetration and aquatic plant growth, just as clay particles do. Clays and silts that cloud the water also provide cover for fish, which use the cloudy water as protection from predators and tend to survive at higher rates when available intermittently.
  • Sand (Particles 0.063 mm to 2 mm): Sand provides a medium for plants to establish and grow. This sediment type provides rearing habitat for juvenile lamprey when located in deposits below large rocks or trees, and acts as a filter to benefit water quality when deposited between gravel particles.
  • Gravel (Particles 2 mm to 64 mm): Ranging from the size of a small blueberry to a large kiwi, gravel offers essential spawning grounds for fish and invertebrates.
  • Cobble (Particles 64 mm to 128 mm): About the size of an orange, cobbles are the framework for bar deposits in river systems. When settled they form a surface that is difficult to mobilize from and creates roughness that encourages small particles to deposit on top of them. While waters flow over through and under these habitat formations the sediments caught provide a diversity of flow in depth and velocity which species depend on in streams.
  • Boulders (Rocks larger than 128 mm): These create physical barriers in rivers that help form log jams, leading to diverse flow patterns and detailed habitats for a range of organisms.

Sources of Sediment in River Systems

image
Fine sediments entering the confluence of the North Fork and the East Fork North Fork after rain dropped on the the Monument Fire scar in July 2023.

Sediment can enter river systems through multiple processes, each contributing to the overall sediment dynamics and ecology of the river. Key sources of sediment include:

  • Erosion: As water flows over land soil and rock can move with it. Depending on the landscape and the soil content these sediments can be delivered to rivers, especially during heavy rainfall or rapid snowmelt.
  • Runoff: Rain and melting snow can wash fine sediments from forests, fields, urban areas, roads, and construction sites into nearby streams and rivers.
  • Bank Collapse: Riverbanks can be eroded by the current of flowing water, particularly in areas with high flow velocities, resulting in banks collapsing directly into the water.
  • Tributary Inputs: Creeks can contribute sediment as they flow into larger rivers, contributing sediments from their own drainage basins.
  • Human Activities: Construction, mining, and land clearing can disturb soil and rock, increasing sediment loads in nearby rivers. Deforestation can also enhance erosion rates when tree roots are damaged or destroyed, leading to hillslope failures into streams.
  • Natural Events: Floods, landslides, wildfires and volcanic eruptions can rapidly introduce large amounts of sediment into river systems, altering habitats and turbidity.
  • Aquatic Organisms: Organisms can influence sediment storage by building dams (beavers) or webs between gravels to capture food and fines (net-spinning caddisfly). Organisms can also mobilize sediment when building nests (salmon) or grazing for food, such as crayfish winnowing fine sediments from amongst gravels.

Pool and Riffle Dynamics

MinuteEarth – Why do Rivers Curve?

When the slope of a river is greater than 2 percent, water moves quickly over rocks and other obstacles creating rumbling mountain streams. Moving downstream as the valley walls open and slope decreases a pool and riffle river system will form. The creation of alternating river bends is based on physical obstacles along the river’s path and water velocity which will form deep (pools) and shallow (riffles). The dynamic plays a crucial role in the movement and storage of sediment as the river runs its course to the ocean. A few key terms:

  • Pools: Pools are deep areas of the river that form over time with flow velocity that scours (or digs) small unstable sediments from the area. Pools offer dynamic habitat during different times of the year that include a varied temperature column in the summer months when waters slow within the river. In winter, during high flows, pools are areas where faster water occurs. The increase in speed in pools relative to their companion riffles is what is responsible for pools scouring to depths found in summer.
  • Riffles: During lower flows that occur in late spring through fall, faster currents are found in riffles because the water surface is steeper on them. Riffles are nursery areas for macroinvertebrates and help oxygenate the water and benefit species that thrive in turbulent conditions. High flows in winter that scour pools deposit sediments from the scour on riffles downstream, and in this way a pool-riffle sequence of habitats is formed and maintained on alluvial rivers.

Salmon and Sediment Interaction

image

Salmon are a keystone species in freshwater ecosystems, and their interaction with sediment is crucial for their lifecycle. During spawning, female salmon seek out gravel beds on riffles and near the streams banks to lay their eggs. These gravel beds, composed of appropriately sized sediment, are essential because they provide the necessary water flow to provide oxygen to fertilized eggs, ensuring their development to the fry stage.

Additionally, the composition and stability of sediment in spawning areas can influence the quality of habitat available for juvenile salmon. Fine sediments, often stirred up during high flow events, can cover spawning habitats, suffocating eggs and reducing the overall success of salmon populations when fines are overly present.

However, Trinity River geomorphologists are learning that too few fines also pose survival risks to salmon. When spaces between gravels where eggs are spawned are left open, turbulence is created through flow within the salmon nest and can jiggle eggs causing abrasion to the egg membrane, leading to mortality. Too few fines can also cause surface flows in a river to be conveyed entirely through a bar, sieving off the juvenile salmon onto dry bar surfaces for predation by birds.

image
Join us Feb. 26 for Science on Tap featuring Dr. Todd Buxton for “Fine Sediment in the Trinity River: History, effects, and current Impacts”

Maintaining a balanced sediment regime within pool and riffle systems is essential not only for river ecology but also for the conservation of salmon, whose life cycles are intricately tied to the health of their sediment-rich habitats. As we learn more about these systems, it becomes increasingly important to recognize how sediment influences river health and ecology, guiding conservation efforts to ensure the survival of these vital ecosystems.

We invite you to join us Wednesday, Feb. 26 for Science on Tap! Dr. Todd Buxton will dive into Trinity River Fine Sediment, history, effects and current impacts. The event is held at the Trinity County Brewing Company and starts at 6pm.

Return to the Feb. Newsletter

The Year Ahead: Science Branch

Posted on by
image
Eric Peterson, Science Coordinator out monitoring algae on the Trinity River in 2024. [Jeanne McSloy, Trinity River Restoration Program]

The Program and partners have approved winter-time Environmental Flows for the next few water years. The intent of moving flows into the winter time is to provide flow conditions that Trinity River salmonids evolved to exploit.  From a scientific point of view, that intent and the reasons behind it are organized into hypotheses that the Trinity River Restoration Program will be testing throughout implementation of the project. 

For the year ahead with the implementation of a new flow management the Program will continue with both short and long-term monitoring projects. Long-term monitoring projects include, outmigrant monitoring (tracking the number and size of young fish heading out to sea), adult escapement monitoring (tracking the number and size of adult fish returning from the sea). Shorter duration studies to examine the flow changes include acoustic monitoring of rock movement, tracking the development of periphyton (algae) on newly inundated floodplains, and investigating the benthic macroinvertebrate (fish food) response to the flows.

image

Currently in the river, spring and fall run Chinook Salmon eggs are hatching and young fish are starting to emerge. Outmigrant monitoring will be ramping up to count these young fish on their migration. The Program is also preparing for some research on how low floodplains, like the Oregon Gulch inundation areas, develop vegetation and if it differs from our more traditional channel restoration sites. 

Last but not least, the Limiting Factors Analysis, is on schedule with initial model development. The project intends to dissect the many limiting factors during the lifecycle of Trinity River Chinook so that the Program can better analyze it’s role and ways to continue restoration efforts more effectively. As the model is developed the task group will assemble the data to parameterize the model, an effort that will continue through 2025. Watch for results of those efforts to come out in summer of 2026! 

Return to the January Newsletter