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Science & Monitoring

Working with community members, local land managers, county, state, tribal, and federal agencies, the Science and Monitoring Committee seeks to develop and implement high-quality and science-driven studies to inform watershed management in the Mad River. 

Program Information

The Mad River is the source of drinking water for 90,000 residents of Humboldt County, and supports many fish and wildlife species, including steelhead, chinook salmon, lamprey, western pond turtle, and foothill yellow-legged frog.  Currently the Mad River is listed on the Clean Water Act Section 303(d) List due to impairments to water quality from sediment/turbidity and high-water temperatures.


Mad River Alliance (MRA) develops and implements monitoring projects to support data needs in the Mad River Watershed by facilitating a coordinated monitoring program to better understand correlations between anthropocentric effects on river flow, water temperature, turbidity, suspended sediment and the biological response. The monitoring projects focus on data gaps where results may affect a stakeholder action, involving the greater community, while being consistent with Mad River Alliance’s mission.


Estuary salinity profile sampling assessed how water diversions are affecting salinity.

2013 and 2014 data were collected to support coho restoration project planning on the lower Mad River.  


Summer steelhead snorkel surveys have been conducted annually since 2013 and integrates volunteers (biologists, agency staff, and citizens in our community). This effort is designed to implement a single focused effort to count adult and 1/2-pound summer steelhead, and supplement historical data collected between 1980–2008. Other species of note include adult and jack chinook salmon, lamprey, mussels, western pond turtle, and non-native New Zealand mudsnail.


• 2013 Mad River Summer Steelhead Report 

• 2014 Mad River Summer Steelhead Report  

• 2015 Mad River Summer Steelhead Report 

2016 Mad River Summer Steelhead Report 

2017 Mad River Summer Steelhead Report

2018 Mad River Summer Steelhead Report


Water temperature monitoring is designed to fill knowledge gaps regarding temperature conditions in the Mad River.  The monitoring study includes deploying temperature loggers at multiple river and tributaries between Matthew’s Dam and the Mad River Estuary to collect temperature data in summer and fall and compare maximum weekly average temperatures to assess the suitability of water temperatures for resident salmonids in the Mad River, especially summer steelhead and juvenile salmonids. Collaborators have included local agencies, business owners, and land managers.


• 2014 Mad River Temperature Monitoring Study Summary Report  

• 2015 Mad River Temperature Monitoring Study Summary Report (In progress)

• 2016 Mad River Temperature Monitoring Study Summary Report (In progress)


Water quality monitoring study is a systematic study designed to measure key components of water quality and contaminants associated with land use (e.g., nitrate-nitrogen, phosphate, dissolved oxygen, total alkalinity, turbidity, temperature, pH, total coliform bacteria, fecal coliform bacteria).


• Data results (In progress)

Summer Steelhead snorkel surveyor during the 2019 surveys.
Summer Steelhead snorkel surveyor during the 2019 surveys.

Summer Steelhead Video