Arcata Fish and Wildlife Office
Pacific Southwest Region
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Trinity River Water Quality Monitoring

About the Trinity River Water Quality Monitoring Program:

Since inception of the Trinity River Restoration Program (TRRP) in 2000, the AFWO continues to evaluate the influence of Lewiston Dam release magnitude and timing on downstream water temperature objectives established as part of the Secretarial Record of Decision. Assessments of the thermal regime are conducted through evaluation of empirical water temperature data collected with continuous recording probes at many locations below Lewiston Dam and modeling. Modeling of water temperature is used by the TRRP to evaluate future alternative flow schedules.

Monitoring data is also used by a variety of partner groups conducting biological assessments as part of the TRRP. Monitoring data are stored in a database and disseminated to interested parties upon request. All instrumentation is subjected to quality control evaluations prior to and following annual deployment. Reports describing these efforts are provided to the Trinity River Restoration Program on an annual basis and are available from this website.


Trinity River Image

Water Temperature Monitoring

The AFWO continues to monitor and report on water temperatures of the Trinity River and lower Klamath River that result from managed flow from Lewiston Dam. Monitoring data is also used to support ongoing biological investigations of various agencies and to support ongoing temperature modeling efforts. Please use the AFWO Request Form to request specific water temperature data.

Annual Reports:


Modeling of the Trinity River and Lower Klamath River

The Trinity River below Lewiston Dam was modeled using the Service’s SNTEMP model, a generalized water temperature model that can be applied to any size watershed or river basin of any complexity.


The model of the Trinity River was used to help define temperature-flow relationships of the mainstem Trinity River and ultimately in development of recommendations for flow releases from Lewiston Dam during the spring, summer, and fall to promote survival of adult and juvenile (smolt) salmonids.


Since the signing of the Trinity River Record of Decision by the Secretary of the Interior in 2000, the SNTEMP temperature model of the Trinity River continued to be updated and refined. Updates of the model were performed for several years including 2006. These updates included incorporation of new water temperature data, refinements to the stream network, and conversion of the SNTEMP model files to the Windows ©-based version of the program called StreamTemp for Windows © developed by Thomas R. Payne & Associates. From 2000 to 2006, the model was used to examine “what if” scenarios associated with a variety of dam release schedule alternatives developed by the TRRP and partners.

Trinity River Restoration Program and Partners:

Last updated: April 16, 2015