represents the flow target for channel maintenance. Likewise, minimal instream flows 

 are also reduced proportional to the channel cross-section from ~2.0 cfs (derived from the 

 Montana Method instream flow model) to ~0.75 cfs, maintained as such during base-flow 

 periods. These flows ranging from a high of 3.05 cfs to minimal base flows of 0.75 cfs 

 are to emulate the natural Wasson Creek hydrograph, which has been modeled from 

 USGS flow data in the Nevada Creek Watershed. Flows above these targets are available 

 for irrigation. 



Fish Populations and other monitoring 



FWP sampled fish populations at four locations (miles 0.1, 1.0, 2.4 and 2.6), 

 measured water temperatures at two sites (mile 0. 1 and 1 .3), instream flows at 3 locations 

 in 2004 and 2005 and initiated whirling disease monitoring in lower Wasson Creek at 

 mile 1.5. Fish population surveys show substantially lower WSCT densities below the 

 upper diversion at mile 2.6, but increasing densities in the downstream direction (mile 1 .0 

 and 2.4) during initial phases (2004 and 2005) of the restoration project (Figure 45). 

 Near the mouth of Wasson Creek (mile 0.1), we also found WSCT in low densities 

 (1.3/100') and low densities of brown front near the mouth of Wasson Creek, in addition 

 to longnose and largescale suckers and redside shiners. 



Flow monitoring results 2005 for Wasson Creek above and below the irrigation 

 diversion are located in Figure 46. We also calculated bankfiill flows from staff gauges 

 located at stable channel cross sections in order to develop both charmel maintenance 

 (3.05 cfs) and minimal instream flow (0.75 cfs) values. 



Water temperatures for summer 2005 were consistently lower (range 4-9 °F) near 

 the mouth (mile 0. 1 ) compared to 2004, while temperatures at mile 1 .3 showed no change 

 (Figure 44). This cooling is likely the result of restoration measures including the early 

 recovery of streamside plant communities. 



A spawning site (McNeil core) survey was also conducted in 2005 on Wasson 

 Creek upstream of the diversions (mile 2.W6). The results show high levels of "fine" 

 sediments in spawning riffles (Results Part IV). This survey provides a baseline for 

 monitoring in spawning areas under alternative grazing methods. 



iv:u- 



I ! 



56 



