Trinity River: Current Conditions

Trinity River: Current Conditions

Concerning news of spring chinook infected with an undiagnosed gill infection have been reported at higher rates than years prior and has the attention of agencies, anglers and those on the river. Although the average rates and the location of these reports have been concerning, some daily rates of reported infections have been alarming and have definitely garnered the attention of regulatory agencies. The evidence of disease is somewhat surprising because upper river temperatures are not exceptionally high. A key differentiating factor hypothesized by fish biologists, may be that the heavy sediment and ash loads from thunderstorms in June may have damaged the gills of the spring chinook that were making their way upriver at that time, stressing them and thus making them vulnerable to disease.

It is helpful to know that there are several advisory groups that meet regularly to discuss Trinity & Klamath River conditions. The KFHAT (Klamath Fish Health Assessment Team) evaluates current conditions and meets weekly and/or as needed throughout the summer and fall period.  The Klamath Flow Augmentations Releases (FARs) group meets bi-weekly (or as needed) and are meant to protect migrating salmon in the summer and fall months, when conditions can become poor in the lower Klamath River. The flows, water temperature, fish observations, and disease rates are all monitored using data collected by several partnering agencies such as the California Department of Fish and Wildlife (CDFW), Hoopa Valley Tribe and Yurok Tribe to determine if a FAR recommendation is needed.

Fish can catch disease if they are stressed and there are several factors that play into this (water quality: including turbidity and temperature, lamprey predation, being handled or caught, etc.). Experts are in agreement that water temperatures at Lewiston are good, around 53 F, which is about 3-4 F cooler than last year. Overall, water temperatures and flows in the upper Trinity River appear suitable for adults and would not be expected to cause gill lesions alone.

To monitor temperatures, there are currently four locations that upload to the USGS website located at Lewiston Dam, Douglas City*, North Fork Trinity River, and in Hoopa. You can view all of these temperature readings by clicking the corresponding links below. The links will also show last year’s (2022) temperature readings for contrast. We see river temps rise this time of year and should start to see them fall slowly down as day lengths shorten – typically starting in August. 

Those involved will continue to discuss any appropriate recommendations for responses to this issue, should a response be warranted. They will continue to monitor the situation and meet to discuss new information in the coming days.

*The Douglas City temperature gauge is now functioning. A replacement from USGS was administered and real time temperature readings came back on-line the morning of July 18. While the gauge that uploads to the internet in real time was damaged, data was still being collected at this site.

Posted in Outreach.