Mushrooms of Trinity County

Posted on February 13, 2026February 15, 2026 by Kiana Abel

Exploring Seasonal and Habitat Patterns of Trinity County Fungi

By: Kiana Abel, Trinity River Restoration Program. Article has been adapted from Kyle Sipes Science on Tap presentation, “Mushrooms of Trinity County: From the South Fork to the Scott Mountains“ January 28, 2026.

Trinity County, located in Northern California, provides a variety of habitats for wild mushrooms. Over 800 species of mushroom-forming fungi have been documented in Trinity County (iNaturalist). In January we welcomed Kyle Sipes, avid mushroom enthusiast, to present, “Mushrooms of Trinity County: From the South Fork to the Scott Mountains” at our Science on Tap event. If you missed his presentation and are interested in foraging for mushrooms, we hope to summarize the presentation here and share some of the tools for mushroom identification. Most notably, his presentation was structured around understanding preferred habitat, symbiotic relationships and key identifying features of individual mushroom types. In this article we hope to give an outline of mushroom hunting through forest types indicating seasonality, habitat details and identification tips. We will explore the life history of mushrooms to enhance understanding of their role within forest ecosystems.

Life History and Ecological Roles of Mushrooms

Mushrooms are the fruiting bodies of fungi, and their life history begins with microscopic spores released into the environment. When conditions are favorable; adequate moisture, temperature, and a suitable substrate, these spores germinate into thread-like structures called hyphae. Hyphae grow and branch underground to form a network known as mycelium, which is considered the main body of the fungus, not the fruiting part that we see above ground.

From there, fungi interact with their habitat either as a decomposer, in a symbiotic relationship, or as a pathogen or parasite to their host. While unique, each interaction reflects the adaptability of fungi and their importance in nutrient cycling, forest ecology, and plant health.

Gwinnett County Master Gardeners Association

Decomposers (Saprotrophic Fungi) Break down dead organic matter such as fallen leaves, wood, and plant debris, recycling nutrients back into the soil.

Decomposer fungi play a critical role in forest ecosystems by breaking down dead organic matter such as fallen leaves, logs, and plant debris. This process recycles nutrients back into the soil, enriching it for future plant growth. In Trinity County, several mushrooms act as decomposers. Lion’s mane (Hericium erinaceus), for example, grows on dead or dying hardwood logs and is known for its cascading white spines. Turkey tail (Trametes versicolor), another common decomposer, forms colorful, fan-shaped brackets on decaying wood and is widely recognized for its medicinal properties. These fungi accelerate the decomposition of lignin and cellulose, substances that are otherwise slow to break down, making them essential for maintaining soil health and supporting the forest’s nutrient cycle.

Symbiotic fungi (mycorrhizal) Form mutualistic partnerships with plant roots, exchanging water and minerals for sugars produced by photosynthesis; this relationship is critical for forest health.

A symbiotic relationship between trees and mushrooms is a mutualistic partnership where both organisms benefit. Most edible and forest mushrooms form mycorrhizal associations with tree roots. In this relationship, the mushroom’s underground network of filaments (mycelium) attaches to the tree’s root system. The tree provides the fungus with carbohydrates produced through photosynthesis, while the fungus helps the tree absorb water and essential minerals like phosphorus and nitrogen from the soil. This exchange strengthens tree health, improves soil structure, and supports the growth of the mushroom. These partnerships are species-specific as certain mushrooms only pair with particular trees, such as chanterelles with Douglas fir or boletes with pine and fir.

Pathogens or Parasites Infect living plants or trees and sometimes cause disease—these are often referred to as fungal pathogens.

Unlike decomposers, pathogenic or parasitic fungi infect living plants or trees, often causing disease or structural damage. These fungi extract nutrients from their hosts, sometimes weakening or killing them. In Trinity County, an example is west coast reishi (Ganoderma oregonense), which causes white rot in living trees and can eventually lead to tree failure. While these fungi can be harmful to individual trees, they also play a role in forest dynamics by creating gaps in the canopy that allow new growth and biodiversity.

Common Mushrooms in Trinity County – By Forest Type

Finding mushrooms in Trinity County changes dramatically with the seasons. Knowing when and where to look is key for successful and safe foraging. Each season brings different species that thrive under specific forest conditions and tree associations. This guide outlines the most common mushrooms found in the county, their preferred habitats, and identification tips to help you distinguish between varieties.

Riparian Hardwood Forests

The Riparian Hardwood Forests are primarily situated alongside rivers or streams with varying degrees of proximity to the water’s edge. These ecosystems connect aquatic and upland areas through dynamic water flow. Various plant species thrive in different hydrologic zones based on their dependence on water. In Trinity County the streams and rivers that comprise riparian areas are the Trinity River, North Fork Trinity River, South Fork Trinity River, not to mention smaller creeks like Coffee Creek, Canyon Creek or Hayfork Creek. Hardwood tree species that are found in riparian river corridors are cottonwoods, like black and Fremont cottonwood, Oregon ash, white alder (the most common riparian tree) and tree willows like red and shiny willow. It is vitally important to understand and identify riparian trees when mushroom hunting.

Yellow Morel (Morchella americanna)

Riparian morels (Morchella species) emerge after the first warm rains, typically March through May. A prized edible that grow with cottonwood, Oregon ash and apple trees here in Trinity County. They are known to populate disturbance areas affected by flood, fire or fallen trees.

Identification Tips:

Honeycomb-like cap with pits and ridges.
Hollow stem and cap when sliced open – a key indicator of a true morel.
Colors range from tan to dark brown.

Other morels that occur with cottonwoods: Various black morels (M. norveginesus, M. brunnea, M. populiphila )

Thimble Cap (Verpa bohemica)

A related species to the morel that may indicate you are slightly early in your search for true yellow morels. Like the yellow morel, the thimble cap occurs with cottonwood species and is as thought to be as delicious as the yellow morel yet restricting consumption of this mushroom is advised (iNaturalist)

Identification Tips:

Wrinkled cap (versus honeycomb-like) with pits and ridges
Pithy filled stem that goes all the way to the cap when sliced open
Colors range from tan to dark brown.

Oyster Mushroom (Pleurotus spp.)

Oyster mushrooms, often seen in restaurant dishes, grow symbiotically with riparian hardwoods like cottonwood, ash, willow, and alder. They are a safe choice for beginner foragers due to the lack of dangerous look-alikes.

Identification Tips:

Gills run all the way down its stem
Grows on trees (versus in the ground)
White, creamy or tan in color

Honey Mushroom (Armillaria spp.)

Honey mushrooms are a parasitic mushroom that infects their host as they feed from it. It is only edible if cooked significantly well, otherwise if undercooked it can make you sick.

Identification Tips:

It grows in big clusters at the base of the tree.
Gills run slightly down the stem.
Has a prominent skirt on the stem called an annulus

Low Elevation Mixed Conifer-Hardwood Woodland

Moving away from the rivers and into the low elevation mixed woodlands look for Douglas fir (Psuedotsuga menziesii), Tanoak with populations in western Trinity and Coffee Creek, madrone and Ponderosa pine (Pinus ponderosa). Most mushrooms in this area will populate in the early fall with first rains and prior to frost or snow.

Cascade Chanterelle (Cantharellus cascadensis)

Chanterelles are a mycorrhizal associate with Douglas fir and true fir trees and if found make for a prized edible when found. Look for chanterelles in the fall after the first rains. The cascade chanterelle (Cantharellus cascadensis) does have poisonous look-alikes to watch out for, including the Jack O’ Lantern (Omphalatus olivescens) in Trinity County and others not yet found in Trinity such as the False Chanterelle (Hygrophoropsis aurantiaca).

Identification Tips:

Has ridges or false gills that run down the stem.
Grows with Douglas fir out of the ground (not from the wood)
When cut in half, the flesh is orange outside and white inside
Should not be confused with the Jack-o-Lantern mushroom or False Chanterelle.

Jack O’ Lantern (Omphalatus olivescens)

A showy beautiful mushroom that grows at the base of oak trees attached to the wood itself. The Jack O’ Lantern mushroom can make you very sick if ingested and can be confused with the cascade chanterelle.

Identification Tips:

True gills, bladelike structures.
When cut in half, the flesh is orange all the way through.
Grows from the wood of oak trees.
Should not be confused with the cascade chanterelle.

White Chanterelles (Cantharellus subalbidus)

White chanterelles are symbiotic with Douglas fir and tanoak trees and like the orange chanterelle make for a prized edible when found. Look for white chanterelles in early fall after rains but prior to freezing.

Identification Tips:

Has ridges or false gills that run down the stem.
White to cream colored
Grows with Douglas fir & tanoak out of the ground (not from the wood)
Gets soggy with rain as time progresses through the fall.

Queen Bolete (Boletus regineus)

Royal boletes, including King and Queen varieties, are prized edibles from the porcini family. They thrive in early fall rains but do not persist through winter. Typically found near tanoak and true oak, these mushrooms form strong mycorrhizal bonds with roots, enhancing tree health and soil nutrient cycling.

Identification Tips:

Pores instead of gills
Has a whitish bloom on the cap when young
Stem shows a prominent netting (reticulation)

Black Trumpets (Caterellus calicornucopoides)

Black trumpets are more common in Western Trinity County than other areas due to the mushrooms relationship with tanoak. These saprotrophic mushrooms decompose dead organic matter, recycling nutrients into the soil and can also be found near black oak, and live oak. They grow in the winter months and can be recognized by their distinct color, shape, and smell.

Identification Tips:

Color is black, grey or sometimes dark brown
Look like trumpets with wavy edges rolled outwards.
Hollow from the base to the edge.
Does not have gills or pores.

Oak Woodlands

Trinity County Oak Woodland [Kyle Sipes]

Oak woodlands are another lower elevation forest of Trinity County made up of trees such as white oak, black oak and blue oak. In these types of forests, most mushrooms in Trinity County grow with black oak, so learning to identify this tree is important when foraging!

Butter Boletes (Butyriboletus spp.)

Butter boletes fruit under white and black oaks in the early fall after early season warm rains.

Bright yellow stem & pores
Spongy underside and a bulbous stem
Bruise blue when nicked on the pore surface versus on the inside

Oak Satan Bolete (Rubroboletus eastwoodiae)

Beautiful yet very toxic mushroom that will fruit under oaks at the same time as butter boletes.

Red pores and cap
Bruises blue on the inside when bisected
Spongy underside and a bulbous stem

High Elevation Conifer Forests

High elevation conifer forests are characterized by dense stands of evergreen trees, primarily conifers such as white fir, Shasta red fir and sugar pine. These forests typically occur at elevations above 3000 feet and are often found on steep, exposed slopes.

In the Trinity Alps, upland morels are the most commonly found edible mushroom. Some species of morels thrive in areas affected by wildfires. The nutrient-rich soil created by fires fosters morel growth, usually within one to two years after a burn but some species don’t appear until several years post-fire. Fires reduce competition and help spores germinate, forming helpful relationships with surviving trees. This makes recent burn sites ideal for spring foraging, resulting in plentiful morel harvests.

There are about 4 to 6 species of morels that adapt well to burn areas, and although they are hard to distinguish, different species appear in these fire-affected zones at various times.

Black Morel (Morchella snyderi)

Besides the burn morels that occur 1-3 years after a burn, Morchella snyderi will be a mushroom to keep your eye out for. M. snyderi occurs in high elevation areas 3-4 years after a burn in undisturbed true fir forests, more commonly found near Mt. Shasta, but can be found in the Marbles and Trinities.

Look for morels a few weeks after the snow has receded.
Occurs in undisturbed true fir forests and several year old burns of the same forest type.
Occurs in the Trinities and very common around Mt. Shasta.

Spring King Bolete (Boletus rex-veris)

Also found in the high elevation conifer forests are the King Bolete. Look for these a few weeks after the fruiting of morels in true fir forests.

Pores instead of gills. Reticulation on stipe
Occurs with true firs approximately 2 weeks after the morel flush.
Often grows as shrumps.
Not as good as fall porcini but still an excellent edible

Photos provided by Kyle Sipes – unless otherwise noted on the image.

The January 28, Science on Tap event was recorded with the presenters permission. Once the video is edited to include the slides, we will post it here!

Kiana Abel, Public Affairs Specialist

As Public Affairs Specialist for the Trinity River Restoration Program, Kiana manages external communications, media relations, and stakeholder outreach. She acts as a liaison between program initiatives and the public, transforming technical findings into compelling narratives that promote understanding of restoration initiatives on the Trinity River. Kiana holds a Batchelor’s in Art History, has spent most of her career in marketing and is focused at the TRRP on bridging the gap between public awareness and resource restoration and management.

Return to the February Newsletter

Water Year 2026 (Oct. 15 – Apr. 15)

Posted on February 13, 2026February 13, 2026 by Kiana Abel

Water Year ’26 thus far has been a rain driven year for storage in Trinity Reservoir. Current storage is a product of early season rain plus elevated levels at beginning of the water year.

Trinity Reservoir September 29, 2025 [Kiana Abel, Trinity River Restoration Program]

In October, Trinity measured in at 70% full with 1.7 million acre feet. Seasonal storms pushed storage over 2 million acre feet (or 84%) in early January leading reservoir managers to implement reservoir management releases after a synchronized storm pulse flow was paired with a post-December 15 storm. By the end of January a lack of rain and snow returned releases to winter baseflow (300 cfs).

Trinity Reservoir Daily Data (CDEC) – click the link for daily data

Storage on [Feb. 13, 2026]: 2,050,645 AF
Capacity: 84%
Historic 15 Year Average (for this date): 131%
Average storage for [Feb. 12]: 1,601,065 AF

Feb. Forecast – California-Nevada River Forecast Center

February’s long range weather forecast is thus far looking a bit more wet than late January.

The volume of environmental flow releases for the Trinity River Restoration Program’s Wet-Season Baseflow Period (Feb. 15-Apr. 14) are determined by a conservative monthly inflow projection for Trinity Reservoir from the California Department of Water Resources (90% B120) in February, March with the final determination in April.

Prior to the official determination, which is published around the 10th of the month, water managers follow the California-Nevada River Forecast Center Median forecast for Trinity Lake inflow to stay abreast of the water year projections thus far.

The graph (shown in screen shot above) can be a little daunting to read, but when armed with the appropriate information is discernable for any viewer.

The Program’s Water-Year Volume Allocation as specified by the Record of Decision is outlined in the table below. The far left column is the threshold amount of state forecasted inflow in the Trinity Reservoir listed in acre feet which determines the center column, water year type. Then in the right column is listed the allocation to restoration for that water year, which includes baseflows.

Return now to an enlargement of the CNRFC forecast screenshot from Feb 13. Check out the light grey box “WY Vol Fcst 10/90%: 1,740/985 kaf” which reads longform as the following;

As of Feb. 11, the 10% of probability for Trinity Lake Inflow is predicted as 1,740,000 acre feet and the 90% of probability is 985,000 acre feet. Translated there is a 10% probability that the Trinity Allocation is predicted as “Wet” and a 90% probability as “Dry”.

As managers track the predicted inflow via CNRFC, the Program’s Flow Workgroup develops hydrograph scenarios to use when the final determination is published by the California Department of Water Resources. The two agencies use different methods when it comes to these prediction tools, the California Department of Water Resources uses data that has a weighted average to compute statewide Snow Water Equivalent (SWE) and is known as a more conservative forecast method when comparing the two.

Wet-Season Baseflow Period (Feb. 15 – Apr. 14)

The next period within the Trinity River Restoration Program environmental flow management is the Wet-Season Baseflow Period, which initiates Feb. 15. The California Department of Water Resources February 90% B120 declaration was published on Feb. 9 as “dry” with the 90% determination at 735,000 acre feet.

With a Feb. B120 determination of “Dry” or “Critically Dry” the Feb 15-Mar. 15 period will not increase releases to the Trinity River and Lewiston Dam flows will remain at 300 cfs (winter baseflow) until Mar. 15.

Environmental Flow Implementation Decision Tree from the Trinity River Winter Flow Project (Abel etal. 2022)

Prior to the next period (Apr. 15 – variable), the Program has a check-in on Mar. 15 to adjust flows based on the March 90% B120 declaration. In April, the Program implements a spring snow-melt and recession hydrograph following the final B120 water year determination by the Department of Water Resources.

Return to the Feb. Newsletter

Bug of the Month: Golden Stones

Posted on February 12, 2026February 13, 2026 by Kiana Abel

By: Chris Laskodi M.S., Fisheries Ecologist, Yurok Tribal Fisheries Department

Stoneflies from the family Perlidae aka Golden Stones

If you are a fly fisherman on the Trinity River, you know one of the top flies in the winter is a golden stone nymph. Unsurprisingly, these stoneflies are one of the most common benthic macroinvertebrates found on the Trinity River. They are especially prevalent in the winter and early spring as most of the other insects have already completed their lifecycle and are growing to emerge the following year.

Photo: A stone fly imitation designed to look like the real thing. [Chris Laskodi, Yurok Tribal Fisheries Department]

These stoneflies typically emerge in late spring so they are almost fully grown and are just packing on calories for the next stage of their life cycle. They are avid hunters and consume anything that can fit in their mouths (mostly Chironomids and Baetid larvae). This hunting activity makes them susceptible to entering the drift either voluntary or involuntary potentially providing a tasty morsel for salmonids that are large enough to eat them. TRRP scientists have noticed an uptick of these stoneflies in the last few months during their regular benthic macroinvertebrate surveys providing insight into the stonefly’s behavior.

*A stonefly from the family Perlidae captured in a recent benthic macroinvertebrate sample.*

Photos provided by the author.

Chris Laskodi, M.S., Fish Ecologist – Yurok Tribal Fisheries Department

Chris serves as the fish biologist/ecologist for the TRRP in the program’s Science branch. Chris has worked on the Trinity River since 2015, previously serving as a fish biologist for the Yurok Tribe and a fisheries technician for the US Fish & Wildlife Service. Chris holds a B.S. in Wildlife, Fish and Conservation Biology from the University of California, Davis and a M.S. in Aquaculture/Fisheries from the University of Arkansas at Pine Bluff. In his free time, Chris enjoys taking friends and family fishing on one of the many watercraft available to him.

Back to the February Newsletter

Program Update – Chinook & Coho Salmon Run-Size Estimates 2025

Posted on February 12, 2026February 13, 2026 by Kiana Abel

By: Kiana Abel (TRRP), Nick Van Vleet (CDFW) & Morgan Knechtle (CDFW)

Preliminary Results for 2025 Klamath Basin Natural-Origin Adult Escapement

Preliminary results from monitoring of natural-spawning fall-run Chinook salmon for the Klamath Basin (which includes the Trinity River Watershed) have estimated adult (age 3-5) returns slightly below the 40,700 target for maximum sustainable yield for 2025. These preliminary results place natural-spawner escapement well above pre-season expectations (<30,000).

The Trinity River accounted for much of this success, with natural-spawner estimates just shy of 24,500 above the Willow Creek Weir. About 14,000 adults are noted within that total. These results move the status of Klamath natural-spawning fall Chinook escapement from overfished to rebuilding status under the regulatory outlines set by NOAA Fisheries. The Klamath Basin has been in overfished status since 2018. The improvement in adult returns is likely due to several factors, including notably, the closure of both the in-river and commercial ocean fishery (with exception of a 2-day recreational ocean fishery last June) in 2025. Habitat enhancements for juvenile chinook and favorable hydrologic and temperature conditions during the rearing period are also likely contributing factors.

Coho Return Estimates Are a Different Story

With significant improvement to Chinook returns, coho returns told a different story. While Central California and Oregon coastal streams reported strong runs (some exceeding recovery targets) Trinity River coho returns remain low. Fish biologists surmise the discrepancy between regions could be due to challenges specific to the Trinity Basin during the rearing period for the 2025 escapement class. Challenges including severe drought, water temperatures during nesting phase, egg health issues like thiamine deficiency, and health of hatchery egg stock. Due to lack of pairs, hatchery operations will rear limited numbers of coho this winter, and no coho specific in-stream Remote Site Incubation projects are planned in the Trinity Watershed this winter.

Management of Klamath Basin Chinook Escapement and Harvest Quotas

A CDFW technician collects salmonid data during the trapping season at the Willow Creek weir.

The Pacific Fishery Management Council (PFMC) adopts harvest plans for Klamath Basin Chinook under the Magnuson-Stevens Fishery Conservation and Management Act, ensuring sustainable harvest and stock rebuilding. Each year, PFMC develops Fishery Management Plans and harvest specifications using pre-season forecasts provided by in-river monitoring, stock assessments, and harvest control rules tied to conservation objectives. The process incorporates broad stakeholder input, including tribal, commercial, and recreational representatives, through public hearings and advisory panels. Scientific review by NOAA Fisheries and state biologists evaluates population dynamics, ocean conditions, and climate trends to model impacts of proposed harvest levels. After public comment and review, PFMC adopts final quotas and season structures, which NOAA Fisheries implement federally, and states align for inland waters. This transparent, science-based framework balances sustainability, equity, and ecosystem health while meeting escapement targets for the Klamath Basin.

Pacific Fishery Management Council | NOAA Fisheries

Trinity River salmonid escapement is monitored annually via three weir locations on the Trinity River at the Willow Creek Weir, Hoopa Harvest Weir and the Junction City Weir. Additionally, biologists from a collection of agencies annually track the population of spring Chinook salmon and summer steelhead via snorkel dives throughout the New River, Canyon Creek, and the North and South Forks of the Trinity River.

Annual adult monitoring efforts at the Junction City weir are implemented by the California Department of Fish and Wildlife with monitoring assistance from the Hoopa Valley and Yurok Tribes and are funded by the Bureau of Reclamation. The Willow Creek weir is operated by CDFW with assistance from the Yurok Tribe during the coho monitoring period. Trapping efforts typically range from late spring/early summer to mid-fall/early winter.

Back to the February Newsletter

Kiana Abel, Public Affairs Specialist

The Year Ahead – Science Branch

Posted on January 16, 2026January 29, 2026 by Kiana Abel

By: Eric Peterson, Science Coordinator – Trinity River Restoration Program

Trinity River in Douglas City. [Kiana Abel, Trinity River Restoration Program]

For the year ahead 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,
and investigating the benthic macroinvertebrate (fish food) response to the flows.

Also, this year we will wrap up a review of our long-term monitoring and modeling efforts and bring recommendations forward on how to better measure our progress.

We will complete the adult Chinook Limiting Factors Analysis, which should give us insights regarding what factors are limiting the return of adult Chinook salmon along with gaming the associated scenarios to help us understand how to improve the use of our tools.

Lastly, we will continue to support the development of a new approach to long-term operations of the Trinity River Division, which should give us better protection of river temperatures in drought years and give us more flexibility with managing environmental flows.

Publications to look out for in 2026

Lindke, K. T., Video monitoring of fish passage at Willow Creek weir: feasibility of validating mark-recapture run size estimates.
Bridegum, J., D. Goodman, T. Daley, R. Smit, J. Boyce, O. Black, J. Alvarez, and K. De Juilio. The Effects of Restoration Actions on Juvenile Salmonid Rearing Habitat in the Trinity River Restoration Reach at an Index Streamflow, 2009 to 2017.
Martel, C. J. Alvare, Z. Reinstein, and K. T. Lindke, Fall Chinook Redd Environmental Conditions and Egg Survival to Emergence in the Trinity River.
Gaeuman, D., K. De Juilio, and C. Laskodi. Efficacy of two-dimensional modeling for assessing spatial variability in stream temperatures.

Return to the January Newsletter

Eric Peterson, PhD – Science Coordinator

Eric grew up in Weaverville, hiking in the Trinity Alps and exploring East Weaver Creek. A natural biologist from an early age, he completed a B.S. in biology and botany at Humboldt State University in 1995, and a Ph.D. at Oregon State University in 2000 in plant ecology with a focus on lichens and forestry. Eric worked as the vegetation ecologist for State of Nevada’s Natural Heritage Program for about 8 years, covering all corners of the state and developing techniques for mapping invasive annual grasses with satellite imagery. Eric joined TRRP in 2009 to manage Trinity River data and coordinate its use across the many offices of our partnership, brought a focus on river ecology by conducting a study of algae growth in the river and tributaries, and is currently the TRRP Science Coordinator.

Eric maintains his interest in lichens on the side as a Research Associate of the California Academy of Sciences, and he chaired the California Lichen Society’s conservation committee for over 20 years. Meanwhile, Eric continues to hike the Trinity Alps and is an active member of Trinity County Search and Rescue. Eric is also on ResearchGate.

The Year Ahead – Implementation Branch

Posted on January 16, 2026January 29, 2026 by Kiana Abel

By: James Lee, Implementation Branch Chief – Trinity River Restoration Program

The Trinity River Restoration Program will work toward the completion of three Trinity River channel rehabilitation projects along with five watershed grantee projects all slated to be implemented in the next year.

In 2026, the Trinity River Restoration Program will be closing out our long-term gravel processing site (Sawmill) in Lewiston in tandem with implementing floodplain restoration and side channel maintenance work at the site. The project aims to significantly improve habitat conditions for aquatic and riparian wildlife in this important area close to Lewiston Dam.

Additionally, the Implementation Branch will be diving into the design phase for most of the remaining 47 sites identified in the 2000 ROD. Closest to implementation are the channel rehabilitation projects in Junction City at Evans Bar and Sky Ranch, and the Rush Creek Confluence in Lewiston, likely to enter work phases beginning in 2027. At Evan’s Bar, TRRP intends to enhance habitat availability for juvenile fish, along with maintaining access to private parcels in the area while improving access at the public boat launch. The remaining site designs, which include Sky Ranch, McIntyre Gulch, and middle Steiner Flat, will start to paint the picture of what the 40-mile restoration reach will look like as the program of work identified within the 2000 ROD nears “completion”.

Watershed Grantee Projects

Through our Watershed Grantee Program, the Implementation Branch will continue to collaborate on five projects to improve conditions in Trinity River tributaries in 2026.

Deadwood Creek Sediment Reduction Project – Northwest California Resource Conservation & Development Council (5Cs)

This project intends to improve sediment delivery in Deadwood Creek, the first major Trinity River tributary below Lewiston Dam. The project will remove legacy mine tailings from Mill Gulch, decommission Thorne Gulch Road, install and enhance 12 rolling or critical dips, remove abandoned vehicles and debris from stream channels and floodplains and build stream enhancement features in Thorne Gulch.

Salt Creek Floodplain Restoration – The Watershed Research and Training Center

This project aims 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. Implementation is scheduled for summer 2026.

Water Resiliency in the Greater River Trinity Watershed for Aquatic Ecosystem and Human Domestic Needs – The Watershed Research and Training Center

The organization is tasked to plan and implement storage tank arrays and establish long-term forbearance agreements to reduce annual water withdrawals from key tributaries to the Trinity River during the summer low-flow period. The project will increase the quality and quantity of natural habitats crucial to the survival of anadromous fishes and aquatic organisms in the Trinity River Watershed. Implementation for two landowners along Brown’s Creek is scheduled for spring 2026.

East Branch East Weaver Creek Migration Barrier Removal – Northwest California Resource Conservation & Development Council (5Cs)

This project will replace an aging culvert that has become a fish passage barrier on the East Branch of East Weaver Creek. The new infrastructure placement will open nearly 2 miles of habitat for anadromous species of the Trinity Watershed.

Weaver Creek Habitat Restoration Implementation – The Yurok Tribe Fisheries Department

The Yurok Tribe Fisheries Department will complete the NEPA process and work towards rehabilitation along the upper section of Weaver Creek, a tributary to the Trinity River. The project will control the spread of invasive plant species, establish habitat connectivity during summertime baseflow conditions, and support populations of threatened Coho Salmon through enhanced floodplain an instream habitat conditions. The Yurok Tribe is collaborating with the Nor Rel Muk Wintu Nation, Federal land managers, the Weaverville Sanitary District, and adjacent landowners for this restoration project.

Return to the January Newsletter

James Lee, MS – Implementation Branch Chief

James Lee grew up near Redding, Ca, but his heart has always been in the Trinity’s, where he chased tadpoles, salmon, deer, and gold nuggets for much of his youth. This love of the outdoors turned into an interest in managing fish, wildlife, water, timber, and other natural resources.

Featured Article – A Reflection on 2025

Posted on January 13, 2026January 29, 2026 by Kiana Abel

By: Michael Dixon, Executive Director – Trinity River Restoration Program

Drone photo of the Oregon Gulch site in the summer of 2025. [Elliot Sarnacki, TRRP]

As we enter 2026, let us pause to reflect on this past year, which was the 25th year of the Trinity River Restoration Program. I’m sure that most will agree that 2025 felt decidedly tumultuous, but we managed to overcome a lot of hurdles and get important work done.

Although we said goodbye to an unprecedented number of TRRPers from across our partnership, the pace of our work did not slow down. While we cannot replace the friendships and personalities of our colleagues who no longer roam our meetings and hallways, those that remain have showed great resolve in their dedication to this program and its mission.

Last year, we completed the Watershed Restoration EA, an ambitious document that will dramatically streamline the environmental compliance process for not just the TRRP’s restoration work, but also for other partners in the watershed. The document was a collaboration with the Bureau of Land Management, the US Forest Service, and our office, and was a heavy lift by many dedicated individuals over several years. We are already seeing the benefits of their hard work with the 2026 construction season approaching.

We abruptly lost our long-term outreach grant with the Trinity County RCD late last spring, but our relationship with them endures. We are actively working on ways to share capacity and continue the work that we do together. Popular events like Science on Tap and youth outreach camps such as the Weaverville Summer Day Camp will continue into 2026.

The Upper Conner Creek restoration Project was completed in 2025. [Elliot Sarnacki, TRRP]

We completed the Upper Conner Creek restoration project. The project rehabilitated nearly 15 acres of floodplain habitat and filled a final puzzle piece of a patchwork of channel restoration projects both up and downstream of the area. The design was the third largest design we have ever implemented in terms of excavation volume. This project saw a significant amount of input from partnerships and stakeholders, leading to a project that met the needs of many while keeping the goal of habitat enhancement for fish and other wildlife at the center. Watching flows from these last several December storms spread out on all that new floodplain has been very exciting – the site looks great and we look forward to watching it evolve.

Speaking of flows, we are now in our second year of implementing the full winter flow project ruleset to better manage and study our environmental flows. For a second year in a row the atmosphere delivered a Christmas storm triggering a synchronized storm pulse. This flow gave the river a healthy scrub (especially up by Deadwood Creek) and set the stage for a vibrant food web to develop as salmon emerge from the gravel.

In the broader Klamath-Trinity watershed, we saw an incredible, unhoped-for number of adult salmon pass the former Klamath dam sites and make it into the upper watershed. Partners in the program were instrumental in making that happen, and there is little doubt the dam removals will pay dividends for the Trinity as well – a rising tide lifts all boats.

Return to the January Newsletter

Michael Dixon, PhD – Executive Director

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.

Featured Article – Wolf Spiders

Posted on September 15, 2025February 12, 2026 by Kiana Abel

By: Kiana Abel, Public Affairs Specialist – Trinity River Restoration Program

Family: Lycosidae

Wolf spiders are an incredibly common spider worldwide with 2400 described species that range in many different habitats, vary in size and coloration, have incredible eyesight and hunt by ambushing, chasing, pouncing and or tackling its prey. In fact, wolf spiders are classified to the Lycosidae family of arachnids, so named after the Greek word (from Ancient Greek λύκος (lúkos)) for wolf due characteristic hunting tactics of the two species.

Thin Legged Wolf Spider [Howard Bruner, inaturalist – Lewiston]

Carolina Wolf Spider *(Hogna carolinensis)*. [wikimedia commons]

McCook’s Split wolf spider (*Schizocosa mccooki).* [Joaquin Hale – Lewiston]

California is home to more than 120 species of wolf spiders, ranging from tiny ground dwellers in the genus Pardosa (thin legged wolf spider) to the quite large Hogna carolinensis (Carolina wolf spider). When discerning between genera of wolf spiders, they can be very difficult to identify in the field without holding each type in your hand [or by using this genius method]. Although the wolf spider’s bite is not dangerous to humans (akin to a bee sting) capturing one on camera or in your hand can be difficult because they are fast – and they are, well. Mostly big. Also hairy. And a spider.

Commonly all wolf spiders share traits such as parental care, eight eyes, active hunting techniques and coloration that hides them within their habitat. Knowing these identifying factors, the wolf spider can be distinguished quite easily from other common California spiders such as the brown recluse look alike, Titiotus californicus, tarantulas or black widow.

Titiotus californicus [Marshal Hedin via iNatrualist]

Desert Tarantula(c) LJ Moore-McClelland via iNatrualist

Western Black Widow. [Joaquin Hale – Lewiston]

Within the Lycosidae family there are 56 described spiders in the genus Schizocosa. Schizocosa mccooki, commonly known as the McCook’s Split Wolf Spider and can be found in Trinity County. This spider is identified by its medium sized (about 1.5 inches) hairy body, active hunting style, eight eyes (two very large center eyes, four under and two upper eyes) and a distinctive “heart mark” on its abdomen. Most individuals live one year, with mating typically occurring in late summer or fall.

McCook’s Split Wolf Spider (*Schizocosa mccooki*). Original posted in inaturalist by (c) William Mason

The rearing and mating process for wolf spiders is unique in the spider world. Common to female wolf spiders, S. mccooki carries her egg sac attached to their spinnerets at the end of their abdomen until their spiderlings hatch. Once hatched, the juveniles remain on their mother’s back until they are ready to disperse into the world.

Wolf Spider Mothers Carry their Eggs – YouTube

Common to male Schizocosa is a complex leg-drumming display used to attract females during mating season. A 2022 study, published in Biology Letters, indicates that males use specific vibratory signals to court their desired female, creating unique and more complex patterns for larger females – the study hypothesizes this may be due to choosing a female that has a large carrying capacity for juvenile spiders once hatched (Choi etal, 2022). The study also found that females picked males with complex coordination of differing signals that may indicate her suiters athleticism (Choi etal, 2022).

Wolf spider, Schizocosa stridulans male courtship – YouTube

Spiders typically have eyes that suit their hunting styles, and unlike web-building spiders, wolf spiders rely on keen eyesight to capture prey. As mentioned earlier, wolf spiders have eight eyes, with a large pair front and center. Their eyesight is enhanced by a interior reflective layer called the tapetum lucidum that helps to shine light back into the spider’s vision effectively enhancing low-light conditions that aide them in nocturnal predation.

Tapetum lucidum is an evolutionary feature found in both predators and prey such as cats, deer, cows, and some spider species. If you are ever interested in hunting wolf spiders, simply head out with a headlamp on a moonless night, shine your light into the grass and look for two reflective eyes shining back at you from the darks of your backyard.

Araneomorph spider of which wolf spiders are categorized. Anatomy from Spidentify

Wolf spiders possess forward-pointing chelicerae, an appendage that almost resembles a well groomed mustache yet operates to aid immobilizing prey while fangs deliver venom at it’s tip. In wolf spiders, the chelicerae are relatively large and well-muscled, giving them the strength to subdue struggling insects during active hunts. Viewed closely, the chelicerae appear dark and glossy, sometimes with fine hairs, and the fangs curve slightly inward at the tips. This arrangement is both efficient for piercing prey and distinguish them from other spider groups such as tarantulas, whose fangs move vertically rather than side-to-side.

In S. mccooki, the chelicerae are proportionally large relative to the spider’s body size and are typically dark brown to black with a polished sheen that contrasts against the lighter patterned cephalothorax. Strong internal muscles allow the fangs to strike with enough force to quickly immobilize prey such as beetles or crickets. Fine sensory hairs line the cheliceral margins, helping the spider detect movement and handle struggling prey. In males, the chelicerae can also serve a communicative role, sometimes being lifted or vibrated in coordination with leg-drumming during courtship.

A Riparian Predator & Prey

Riparian corridors are home to a wide range of species that link terrestrial and aquatic food webs. Among these, the wolf spider is a key ground-dwelling predator that helps regulate insect populations and provides prey for higher trophic levels.

Wolf spiders are widespread in open habitats such as grasslands, chaparral, and riparian habitats where cobble bars, woody debris, and leaf litter provide hunting grounds and cover. These microhabitats are important refuges not only for wolf spiders but for the many insects they consume. As wolf spiders actively stalk prey such as earwigs, beetles, ants, and crickets, consuming them helps moderate insect communities which indirectly supports plant health thus contributing to ecosystem stability. S. mccooki and other wolf spiders also contribute to cross-boundary energy flow by serving themselves as prey for birds, amphibians, reptiles, and mammals.

Mccooks Split Wolf Spider carrying its eggsac. [Martin Galli, inatrualist]

Recognizing the ecological functions of wolf spiders highlights why observation is often a better response than eradication. These spiders are integral components of riparian and terrestrial ecosystems, regulating insect populations and serving as prey for higher trophic levels. Their hunting strategies, reproductive behaviors, and physiological adaptations illustrate the complexity of predator–prey interactions that sustain biodiversity. By taking time to identify and observe a spider before removing or killing it, we not only learn more about local species but also foster an understanding of the interconnected roles that maintain ecosystem stability. In this way, simple curiosity can translate into conservation-minded awareness.

References

Kiana Abel, Public Affairs Specialist

Plant Spotlight – Poison Oak and Skunk Brush

Posted on August 27, 2025August 27, 2025 by Kiana Abel

Toxicodendron diversilobum and Rhus trilobata

image comparison — On the left is poison oak, and the right is skunk brush. Notice the distinct ‘stem’ on the central leaflet on the poison oak plant. Skunk brush leaflets do not have this feature. *[Simone Groves, Hoopa Valley Fisheries Department]*

Editor’s note: The shrub with the common names which include skunk brush, basket bush, fragrant sumac, lemon sumac, and lemonade bush is known across North America as both Rhus trilobata and Rhus aromatica. The nomenclature in this document follows McBain and Trush (2005) and refers to the plant as Rhus trilobata.

Have you ever walked in the woods and tried to identify poison oak along the path? Some folks walk with extreme caution as soon as they step from pavement and defined trails, driven by fear of injurious rash caused by this plant. The most common way that I hear folks identify poison oak is through a common rhyme “leaves of three, let it be.” This is an easy phrase to remember, but there are some loopholes in this simple rhyme. There are several look-alike species that cause no harm, and are in fact quite tasty, and can be eaten. Let’s start with the commonly defined ID features used in the Jepson manual to distinguish the two genera.

Poison Oak (Toxicodendron diversilobum) has axillary flowers which appear between the leaf axles with a pedicel, or stem at the base which causes the flowers and fruit to be spaced apart; leaflets adaxially shiny or oily-looking on the top; fruit creamy white or papery looking.

Skunk brush (Rhus trilobata) (also called basket bush, lemon sumac, fragrant sumac, and lemonade bush) flowers appear on the ends of the branches, also called “terminal”; flowers are often nearly sessile or appear tightly packed; leaflets dull, not very shiny; fruit red and often sticky. There’s an interesting additional flower mannerism in skunk brush – the flowers often are only male or only female on individual plants, but sometimes bisexual flowers can also be found on plants, this term is called polygamodioecious. This is why a whole area will have no fruit, and then a patch of plants might be loaded full of fruit.

Speaking of its red fruit, skunk brush’s other common names, lemonade bush and lemon sumac, refer to the berries. They have a sour, lemony flavor to them. It is said that early pioneers steeped the berries in water, and then added sugar to make lemonade. The berries are also eaten directly and are considered an important food source by some Native American tribes. Many wild animals consume the berries of both poison oak and skunk brush, particularly birds and small mammals, although they are not a preferred food source. Their tendency to stick to the stems through the winter makes them good emergency food for animals when other foods are scarce.

Skunk Brush (*Rhus trilobata*) with fall berries. [Simone Groves, Hoopa Valley Fisheries Department]

Expanding beyond the features that the Jepson uses for ID there can be a lot more subtlety of distinguishing observations between the two species. The more that you look at these two, the more you will learn to differentiate between them in your own way! Here are a few more features that I have noticed over the years.

Leaves

Remember “leaves of three, let them be”? Well the more accurate saying should be, “leaflets of three, let them be” because according to plant anatomists, the three “leaves” on a poison oak plant are actually a single leaf, divided into three leaflets. Poison oak appears to have a stem on the terminal leaflet which separates it from the basal lobes. The leaves often have 3-dimensionality to them, either with ruffled edges, or a central crease along the midrib of the leaf, with venation standing out as slightly white when viewed from above. Any leaf features on poison oak can be highly variable and thus expect it to surprise you at times. As field botanists often joke that poison oak will often take on the look of nearby plants.

Skunk brush tends to have the front leaflet be a little larger and the back appear slightly reduced in size. These leaves do not have a stem attaching the leaflets together. The leaves tend to be extraordinarily flat or could be described as “2D.” Often times the venation is only distinctly visible from the abaxial or underside of the leaf. Sometimes there is a little trench-like crease from the topside but the veins don’t stand out looking down on it.

The last feature that is helpful for differentiating these two species, is the color and mannerisms of the stems of each plant, even when dormant. Poison oak tends to have yellowish stems, often times with hibernating buds that look like little pink primordial hands. Poison oak is also known for making little adventitious roots on the branches which helps it climb trees and spread aggressively over the ground. It isn’t unusual to see poison oak growing as either a shrub or a vine (but it’s not the same as ‘poison ivy’, which is not found in California.

The “yellowish” stems of poison oak. [Simone Groves, Hoopa Valley Fisheries Department]

Skunk brush has branches that look ashy grey or pinkish purple and in early spring they tend to be layered in a tender fuzz that is reminiscent of the velvet covering a young deer’s antlers. Also, the smell of skunk brush is distinctly pleasant, both when cut and when burned. One might imagine these sticks being used for incense, or something similar.

The tender fuzz covered stems of skunk brush. [Simone Groves, Hoopa Valley Tribal Fisheries]

Both species tend to come out of winter dormancy around the same time. However the first features to awaken in poison oak are its new shiny leaves, whereas the first feature to appear for skunk brush, are the flowers. Often times the timing of this awakening from dormancy is highly variable year to year and can track the warmth changing around the landscape in a very intimate way.

Comparison of the two species in early spring when poison oak shows leaves first and skunk brush’s flowers are first. [Simone Groves, Hoopa Valley Fisheries Department]

Initially, botanists placed both poison oak and skunk brush in the same genus- Rhus. This name is Greek for ‘rhous’ which means flow, or stream. Some have thought that this might refer to the sticky sap that is excreted when cut, but others have rejected this claim. The reclassification of poison oak to its own genus “Toxicodendron” occurred in the early 20th century as the genus was given definition and separated out those representatives within Rhus that caused skin irritation. Toxicodendron means “poison – tree” in Greek which was also a contentious definition because technically the plant is not poisonous, but is an irritant, and in fact has many medicinal and beneficial properties. In Hupa language the word for poison oak is k’e:k’ilye:ch’. In Yurok the word for poison oak is me’yk’welep’. The Karuk word for poison oak is kusvêep.

Urushiol is the chemical present in the Toxicodendron genus that is renowned for irritating the skin. This oil is described as similar to machine oil in its difficulty to remove. Some recommendations suggest removing it using a sudsy soap and an abrasive scrubbing surface under cold water. Also, some home remedies recommend rubbing clay or dirt on fresh oils as it can absorb the oils and reduce the interactions with your skin cells. According to the National Library of Medicine, the reaction caused by urushiol is a Type IV Hypersensitivity reaction which is often stimulated in 48-72 hours after exposure and is a T-cell mediated immune reaction, suggesting that it is the between-cell interactions that cause the body’s immune response to the oils.

As with many plants in the California landscape, both poison oak and skunk brush have a fire relationship. Although poison oak burning can aerosolize the urushiol, if the fire develops to just the right amount of heat and time of day, a completely safe fire can “stand up” and send the toxic smoke harmlessly into the upper atmosphere. Some indigenous descriptions report that the current prevalence of poison oak in forest understories is due to the lack of short fire return intervals on the landscape. Skunk brush was used by many tribes in California as a basketry stick. These stems were burned, just as hazel was for its shoots. In my personal experience burning with North Fork Mono led by cultural fire practitioner and Tribal Chairman, Ron Good, when the color of the ash turns purple, it can indicate that the fire and embers are the right intensity and is cool enough to cultivate the healthy regrowth of the plant. With burning and fire intensity, ash color and burned soil color as well as charcoal remains can all be an indicators of the temperature of the flames and their effects on the plant and soil communities. For more information dig into the resources at the FRAMES federally hosted fire effects resource page.

A common medicinal concept held by many of the tribes in our northern California region is that the medicine can be found near the cause of the problem. Poison oak is the classic example of this. Mugwort is a strong medicine for neutralizing poison oak, in particular salves made from it, but also a tea, taken internally can soothe the body’s reaction. Other common medicines include manzanita and madrone bark which a cooled tea of these can soothe the blisters and calm the body’s reaction. This idea can remind us that rather than thinking of the world as full of dangers and poisons that lie just beyond the edge of the path, rather that medicines and foods are always near to provide support and soothe the ails that arise along the way.

Resources:

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.

Featured Article – C. shasta

Posted on July 18, 2025February 12, 2026 by Kiana Abel

A tiny parasite in the Klamath & Trinity Rivers

*C. shasta a microscopic parasite. [captured as a screenshot from youtube, Shasta 2 Life Cycle Oregon State University]*

What is C. shasta?

Ceratonova shasta (C. shasta) is a microscopic parasite that is native to rivers of the Pacific Northwest, including the Klamath and Trinity Rivers. Infection is most severe for juvenile salmon but can impact returning adults as well. The impact of an infection is highly influenced by water conditions like temperature, flow, and seasonality. If conditions are right for the parasite’s host worm, C. shasta can rapidly proliferate and lead to severe infections that can be devastating to populations. In 2021, after years of drought that impacted river conditions juvenile salmonid deaths from C. shasta in the lower Klamath reached into the hundreds of thousands [1, 2].

To survive, C. shasta needs two hosts

1. A carpet of tiny worms
C. shasta starts its life inside a freshwater worm, called Manayunkia occidentalis. The worm, smaller than an eyelash, lives in mud and on rocks below the surface of a river or reservoir in colonies that can resemble an underwater carpet. Inside the worm, the parasite grows and turns into a new form called an actinospore. Once an actinospore, the worm releases the microscopic parasite to float in the water column and wait for its next host [3].

2. Salmon and Trout
As they swim young salmon breath in the actinospores allowing the parasite to attach to the gills and then enter the fish’s body. The parasite then travels to the fish’s intestines, where it multiplies and causes internal damage. This makes the fish sick and weak, causing many to succumb to the infection. The cycle continues when infected fish (including adults) release more spores back into the water after they die.

Jerri Bartholomew Ph.D. explains the complex lifecycle of C. shasta and her discovery of the second host involved in the disease. She presents some of the questions being explored in a collaborative effort to help salmon survive in the Klamath River.

Are Adult Salmon Affected?

Adult salmon can be infected with C. shasta however the severity is influenced by other stressors. Typically, adults encounter the microscopic spores during upriver migration through areas with high spore loads (like the lower Klamath River during spring/summer). If the fish is stressed from high water temperatures, poor conditions or other pathogens, C. shasta could lead to pre-spawn mortality or failure to spawn. Although typically resistant, if infected, adults can act as a carrier of the parasite – shedding spores when they die and decompose. If the spores are shed in a system that does not have adequate flushing flows during the ensuing winter months, juveniles from the area could be affected. While some disease impacts to adult salmon are possible, if conditions in the river are favorable, adults are generally more resistant to effects of the disease than juveniles.

The Klamath River

Salmon health and vitality is of utmost importance for Klamath indigenous groups like the Yurok, Quartz Valley, Karuk, and Hoopa Valley Tribes. For millennia salmon have provided sustenance and are celebrated as integral to the health of people, culture, tradition, and economy. The continued decline of salmon due to C. shasta and other human-enhanced factors are deeply felt by local people and led to the decade’s long advocacy to remove four hydroelectric dams on the Klamath River.

In 2023 and 2024 these dams on the Klamath River were removed, allowing salmon, steelhead and lamprey to reconnect to 400 miles of spawning habitat. It is the largest dam removal project in U.S. history, to date. Ecological goals for dam removal are to improve water quality, restore resources to Klamath River Tribes, restore habitat for salmonid species, and improve the health of salmon and steelhead [5].

The Klamath River is home to several salmon species that are important to Native American tribes, commercial and recreational fishers, and the ecosystem as a whole. Although infections occur in all species of juvenile salmon or trout, if the parasitic worm host is allowed to thrive, results can be devastating for some salmon species. One such species of concern are Coho salmon, which are recognized as “threatened” in the Klamath and the Trinity and are especially vulnerable to population scale impacts from large scale fish kills propagated by parasites.

Toxic algal blooms were a problem in the stagnant waters sitting behind the dams on the Klamath River since the dams were built. Photo by Stormy Staats/Klamath Salmon Media Collaborative via KRRC.

What made the lower Klamath River a hotspot for C. shasta? Below Iron Gate dam, the primary reasons were twofold. First, scouring events from winter storms were blocked by dams failing to disperse sediment. Second, waters held in several chains of reservoirs warmed. Ultimately these combining factors led to robust habitat conditions for the parasite’s aquatic worm host. Fish heath experts in the Klamath Basin are hopeful that dam removal will mitigate previously favorable growing conditions for the host worm [6]. Removal of JC Boyle, Copco 1 & 2 and Iron Gate dams will allow for a more natural flow of water from tributaries and potentially help to scour growth of the host worm with winter storms.

Hope for Trinity River Fish Populations

The Trinity River joins the Klamath River approximately 44 miles above the ocean, so its fish are subjected to the conditions of the lower Klamath River during their migrations. Beginning in late winter juvenile chinook begin to migrate downriver feeding on drift invertebrates, resting and digesting in warmer slower waters. Once they meet the mild saline waters of the Klamath estuary, they begin a smoltification process where their bodies change and adapt from freshwater to saltwater. Cold temperatures and salinity may reduce progress of disease, but do not eliminate infection [1].

Because of their migration paths, Trinity River fish populations were part of the juvenile fish kill on the Klamath River in 2021. This event, along with historic drought conditions that followed, allowed for pathogens like C. shasta to play a significant role in returning adult escapement. Since most Chinook exhibit a 3-5 year life cycle, we’re still experiencing the loss of these juvenile fish today. Historically low returns of adult chinook salmon have prompted recreational fishery managers to close in-river salmon fishing seasons for a third consecutive year [8, 9]. Although the immediate impacts have been devastating for recreational anglers and river enthusiasts, there are many hopes (and also many unknowns still to be learned) following the removal of the dams. The primary hope for Trinity River outmigrant fish to experience less frequent and less severe infections once they reach the Klamath River so that juveniles as well as adults can manage natural stressors and thrive.

Klamath Fish Health Assessment Team

The Klamath Fish Health Assessment Team (KFHAT) is a technical workgroup which formed during the summer of 2003 with the purpose of providing early warning and a coordinated response effort to avoid, or at least address, non-hazardous materials related fish kill events in the anadromous portion of the Klamath River basin [10].

To accomplish this goal, KFHAT created a network of experts and monitoring efforts through which information about current river and fish health conditions in the Klamath Basin can be shared among participants, the general public, and resource managers.

Every year, beginning in late April, members of KFHAT hold meetings to assess Klamath Basin fish health along the Klamath and Trinity Rivers and their main tributaries. The group publishes observations as well as a readiness level map based on those observations on a public facing website: Klamath Fish Health Assessment Team (KFHAT) after each meeting.

How are juvenile populations fairing this out-migration season? The wet winter of 2024/2025 has set the system up with favorable fish health conditions, but our area’s typical hot July weather can lead to stressful lower river environments. Thus far the 2025 monitoring season has seen some irregularities with regards to concentration of C. shasta. Klamath Basin water quality monitoring is implemented annually by a team at Oregon State University and recent monitoring results are showing higher than normal spore counts of C. shasta in geographic areas that are puzzling scientists [10]. In the lower river, screw traps are catching Trinity River hatchery-released yearlings from the fall and spring brood stocks with infections [10]. Although these conditions exist each year, they vary in severity and salmon evolved to this specific weather pattern. The species stay healthy by seeking cold water refugia located in deep stratified pools and cold-water tributary mouths during the hottest weeks of the year. Also typical to the area, wildfire can aid conditions when smoke sits in drainages, reflecting the sun’s heat back into the atmosphere and therefore cools air and water temperatures.

Updated after set meetings, the KFHAT map presents readiness levels for the Klamath Basin in a visual format. [Screenshot taken July 18, 2025 from the Klamath Fish Health Assessment Team website]

Although this year’s conditions thus far are concerning (note the yellow readiness levels in the map above), many juvenile salmon are in the last stages of migration to the ocean and are likely in the lower Klamath river undergoing smoltification or learning to live in their new ocean environment. What will conditions be when they return to spawn in our river in 2028, 2029, or 2030? Of course, only time can tell, but with the removal of four Klamath Dams, river managers are hopeful that, when it comes to controlled conditions, Trinity and Klamath run salmonids will have a more favorable environment than what populations have encountered for over six decades, and they might be more favorably armed to withstand what mother nature may bring their way.

Thank you to Dan Troxel, California Department of Fish and Wildlife lead on the Klamath Basin Fish Health Assessment Team and Morgan Knechtle from California Department of Fish and Wildlife for providing detailed edits to this article.

References

As massive fish kill continues on Klamath River, Karuk Tribe declares state of climate emergency
Serious fish kill consumes the Klamath River | Local News | heraldandnews.com
Ceratonova shasta – Wikipedia
Benefits of Klamath River Renewal – Klamath River Renewal
TRRP: Fish of the Trinity River
Dam removals, restoration project on Klamath River expected to help salmon, researchers conclude | Newsroom | Oregon State University
Chinook Salmon Fact Sheet – U.S. Fish and Wildlife Service
Another Commercial Salmon Season Closure is Expected | News Blog North Coast Journal. April 22, 2025.
CDFW News | Limited Chinook Sport Fishing to Reopen in 3 Central Valley Rivers, excludes Klamath Basin and Mainstem Sacramento.
KFHAT_2025_Report_5.pdf

Further Reading

Key Parasites of Salmonids in the Klamath and Trinity Rivers

Parasite	Type	Key Life Stage Affected	Impact Severity	Notes
Ceratonova shasta	Myxozoan	Juveniles	High	Major mortality factor in Klamath
Parvicapsula minibicornis	Myxozoan	Juveniles	Moderate	Common co-infection
Nanophyetus salmincola	Trematode	Juveniles & adults	Moderate	Common in Trinity River fish
Ichthyophthirius (“Ich”)	Protozoan	All stages	Variable	Outbreaks under warm conditions
Myxobolus spp.	Myxozoan	Juveniles	Low–moderate	Rare, possible underdiagnosis
Henneguya spp.	Myxozoan	Juveniles & adults	Low	Occasional gill infections
Gyrodactylus, Dactylogyrus	Monogenean	Juveniles	Low–moderate	Mostly hatchery-associated
Sea lice	Copepod	Smolts in estuary	Moderate	Not a primary river concern upstream

Key Parasites of Salmonids in the Klamath and Trinity Rivers

Return to the July Newsletter

Kiana Abel, Public Affairs Specialist