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Colorado River - 15-Mile Reach The 15-Mile Reach of the Colorado River extends from Palisade, Colorado (RM 185), downstream to the confluence of the Gunnison River at about RM 170 (Figure 4). The Colorado River Recovery Program (Osmundson et al. 1995) considers the 15-Mile Reach important for endangered fish recovery. Flows are an issue because of two major upstream diversions that divert flow from the river during the irrigation season (April 1 to November 1). The Government Highline diversion is located in lower Debeque Canyon (RM 193.7) and the Highline canal has a capacity of 1620 cfs. The Grand Valley diversion dam is at RM 185.4. The Grand Valley canal has a capacity of 640 cfs. A USGS gage, which is located about 0.4 km downstream from the intake for the Grand Valley canal (Figure 4), began operation in 1990. Flows at the Palisade gage are typically 1200 to 1600 cfs less than above the diversion structures in spring and summer. Winter (November to March) flows in the 15-Mile Reach do not appear to create fishery concerns. Flows recorded at the Cameo gage (RM 199.9) appear to be at least at pre- development levels or higher due to senior water right calls at the Shoshone power plant in Glenwood Canyon. Also there can be additional releases for power generation from Green Mountain Reservoir (Per comm. Karen Flogequest (USBR). Flows recorded at the Palisade gage are usually higher than at Cameo between November and April because Plateau Creek joins the river at RM 193.3. Pitlick (1999) determined bankfull flow to be near 22000 cfs for the 15-Mile Reach. There are two study sites in the 15-Mile Reach. In 1999, bed topography was mapped from the boat launch at Corn Lake (RM 177.5) downstream to RM 175.3 (Figure 4). This station is named the Corn Lake Site. The Corn Lake site length, which is 3.9 km long and has an average width of 55.2 m at a flow of 1400 cfs, was electro-fished in 1999, 2000 and 2001. The river in this section includes five small backwaters. Flow is generally confined within the main channel as opposed to a braided channel (Figure AF7). The Clifton Site was added in 2000. This site is about 300 m upstream from the Corn Lake site. The Clifton site is from RM 177.7 to 180.4 and has a total length of 4.2 km. In this section, the river has split flow in two large sections of the channel. There is an old diversion structure located at RM 179.7. The dam backs up water along the north shoreline. There is a large backwater at lower flows. Smaller backwaters like those found in the Corn Lake are uncommon in this site (Figure AF8). The peak flow for the Palisade gage in 1999 was 12700 cfs on June 10. The peak flow in 2000 was 13,500 cfs on May 31. In 2001 the peak flow was 8,410 cfs on May 21. The median peak flow for the 11-year Palisade gage history is 13,500 cfs indicating that peaks for 1999 and 2000 were near normal. Typically, flows in March are near 2000 cfs, but in some years flows can-drop after April 1 due to diversions into the Government Highline and Grand Valley canals. In 1999, flows during the ascending limb (April and May) of the hydrograph flow dropped to 435 cfs on April 15, 1999. That was the minimum flow for the year. The minimum spring flow was 1110 cfs on April 5`s, 2000 and 500 cfs on April 17`", 2001. 19