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Table 2. Mean monthly and monthly minimum flows recorded at the Palisade gage, 15- Mile Reach, Colorado River for summer months during the three years of the study. Year July August September October (cfs) (cfs) (cfs) (cfs) 1999 Mean 4,721 2,221 1,752 1,837 2,500 1,380 1,180 1,430 Minimum 1,271 913 986 916 2000 Mean 648 581 665 543 Minimum 995 1,133 1,014 809 2001 Mean 477 686 754 -535 Minimum Dolores River The headwaters of the Dolores River lie in the San Juan Mountains. The river flows mostly northward about 200 miles to its confluence with the Colorado River in Utah. The McPhee Dam, which stores water primarily for irrigation, regulates flow for most of the river's course. The McPhee Dam has a capacity of 38 1000 acres/feet and began storing water in 1984. The magnitude of runoff and peak flows are much reduced compared to before 1984. The San Miguel River is of comparable size and joins the Dolores about 117 miles below the McPhee Reservoir. The San Miguel has a relatively unregulated flow. Access points for boat launches and take-outs were found to be very limited over most of the Dolores River's length. A study site was located in the Big Gypsum Valley, which is 14 river miles downstream from the Slick Rock Bridge and 34 river miles upstream of the Bedrock boat launch (Figure 5). The Dolores River Guidebook (DeVries and Maurer 1977) starts with River Mile (RM) 0.0 at the Bradfield Bridge. The confluence of the Dolores with the Colorado River is RM 171. We used the river guide in reverse RM order to identify landmarks. Beginning at the confluence as River Mile 0.0, the Utah-Colorado State line is RM 22.4, and the Big Gypsum Study Site is RM 107.1 to 109.9. The study site starts at the BLM Gypsum Valley Recreation site and ends about 3.0 miles downstream at the 20R (county road) bridge crossing. The study station is about 70 river miles downstream from McPhee Reservoir. 22