Results & Discussion Cont. Acknowledgements & References An Assessment of Canopy Cover, Pool Depth, and Stream Temperature to Determine Habitat Suitability for Juvenile Salmonids in the Upper Main Stem Eel River Watershed Ariel Dasher, Emily Cooper, Alison O’Dowd Humboldt State University Introduction Results & Discussion Results & Discussion Cont. The Eel River is the third largest watershed completely contained in California and was once the third largest salmonid producing river. Currently the salmonid population is 1-3% that of historic levels. Cape Horn Dam and Scott Dam were built in 1906 and 1922, respectively as part of the Potter Valley Project (Fig.1) to divert water from the Eel River to the Russian River. Scott Dam prevents fish passage and is up for relicensing in 2022. If the Potter Valley Project were to be modified or removed, it would potentially open up many miles of habitat for anadromous salmonid species, particularly threatened steelhead trout (Oncorhynchus mykiss). The goal of this project is to determine habitat suitability for juvenile steelhead upstream of Scott Dam by measuring pool dimensions and temperature. Temperature is one of the most important indicators of habitat quality for salmonid species. The temperature range for rearing of juvenile steelhead is 10℃ to 26℃ (Carter, 2005). This study took place in the early summer 2016 so it is important to note that the temperatures are subject to change as the dry season progressed. None of the temperatures recorded in this study crossed the upper temperature threshold for suitable juvenile steelhead conditions. Canopy Cover Water temperature mimics air temperature on a daily basis and when there is no canopy to provide shade, stream temperatures are typically higher. The temperatures of streams with a high percentage of canopy cover (Fig. 3) were generally lower than the temperatures of streams with a low percentage of canopy cover (Fig. 4). In 1987 there was an experiment done regarding canopy cover and temperature pre and post the large Silver Complex fire. Pre-fire there was nearly 90% canopy cover, post-fire the canopy cover was reduced to 30%, temperatures post-fire increased by nearly 10℃ (Amaranthus et al, 1989). Another study regarding canopy cover was done in 2004 where a stream was covered with black plastic to create artificial canopy cover and temperature was monitored directly upstream, underneath, and downstream of the plastic. It was found that water and air temperatures were cooler under the plastic as well as downstream (Johnson, 2004). The data (Fig. 5) also show canopy to have a significant inverse relation to temperature, as expected. Depth Maximum pool depth and average pool depth were also expected to have a significant inverse relationship with temperature. However this was not the case, and it was found that pool depth has very little correlation to temperature (Figs. 6 & 7). This is not to dismiss depth being an important factor that influences temperature, but there maybe other factors that have stronger influences on temperature. Research Questions Are pool temperatures in waterways of the upper Eel River able to support suitable juvenile rearing conditions for steelhead trout? Do pools of the upper Eel River exhibit a relationship between lower temperatures and maximum depth, average depth or canopy cover? Study Area Figure 6. Temperature and average depth for each pool found within a given reach(color coded) and a linear regression for all reaches combined. Figure 3. (left) Example photo of high percentage canopy cover. Photo Credit: Emily Cooper Figure 4. (above) Example photo of low percentage canopy cover. Photo: http://mw2.google.com/mwpanoramio/photos/medium/30568158.jpg Figure 1 (left). Northern California map displaying the Eel River, Russian River, and Potter Valley Project. Map created by E. Cooper, 2016; NMFS, 2016 Figure 2 (below). Study site map displaying all survey points visited, and color coded by reach type. Points circled in red are the sites specific to this study. Map created by E. Cooper, 2016; NMFS, 2016 Figure 7. Temperature and maximum depth for each pool found within a given reach (color coded) and a linear regression for all reaches combined. Figure 5. Temperature and canopy cover for each pool found within a given reach (color coded) and a linear regression for all reaches combined. Conclusions Our study determined that if the Potter Valley Project were to be modified or removed to allow fish passage, summer temperatures in the upper Eel River above Scott Dam would be able to support juvenile rearing habitat for steelhead. It was also found that canopy is related to stream temperature, where as depth was not. Given the chance to improve upon this study continuous temperature monitors may be beneficial to create a more accurate comparisons of pool temperatures. Acknowledgements & References Methods Acknowledgements: Erik Daniels (undergraduate research partner), Rroulou’sik REU Coordinators Dr. Matthew Johnson and Dr. Seafha Ramos, National Science Foundation, INRSEP, Intertribal Student Services, Mendocino National Forest, Cal Trout, and Humboldt State University. References: Amaranthus, Michael, Howard Jubas, and David Arthur. "Stream shading, summer streamflow and maximum water temperature following intense wildfire in headwater streams." (1989). Carter, Katharine. "The effects of temperature on steelhead trout, coho salmon, and Chinook salmon biology and function by life stage." Implications for the Klamath River total maximum daily loads. California Regional Water Quality Control Board. North Coast Region, Santa Rosa, California (2005). Johnson, Sherri L. "Factors influencing stream temperatures in small streams: substrate effects and a shading experiment." Canadian Journal of Fisheries and Aquatic Sciences 61.6 (2004): 913-923. Used sampling protocol from the California Salmonid Stream Habitat Restoration Manual to measure habitat attributes at each site Recorded three depths per pool visited, including maximum depth Visually estimated percent canopy cover at each pool Recorded temperature at maximum depth of each pool