Stream: Blue Creek Executive Summary

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Staff Analysis and Recommendation Summary The information contained in this report and the associated instream flow file folder forms the basis for staff's instream flow recommendation to be considered by the Board. It is staff's opinion that the information contained in this report is sufficient to support the findings required in Rule 5.40. Colorado's Instream Flow Program was created in 1973 when the Colorado State Legislature recognized "the need to correlate the activities of mankind with some reasonable preservation of the natural environment" (see 37 -92 -102 (3) C.R.S.). The statute vests the CWCB with the exclusive authority to appropriate and acquire instream flow and natural lake level water rights. In order to encourage other entities to participate in Colorado's Instream Flow Program, the statute directs the CWCB to request instream flow recommendations from other state and federal agencies. The Bureau of Land Management (BLM) recommended this segment of Blue Creek to the CWCB for an increased water right under the Instream Flow Program. Blue Creek is being considered for an increase because it has a natural environment that can be preserved to a reasonable degree with an increased instream flow water right. Blue Creek is approximately 3.5 miles long. It begins at the confluence of Big Blue Creek and Little Blue Creek and terminates at the confluence with Morrow Point Reservoir. 100% of the land on the 3.53 mile segment addressed by this report is publicly owned. Blue Creek is located within Gunnison County and generally flows in a southerly direction. The subject of this report is a segment of Blue Creek beginning at the confluence of Big Blue Creek and Little Blue Creek downstream to the confluence with Morrow Point Reservoir. The proposed segment is located approximately 5 miles southwest of Blue Mesa Dam. The staff has received only one recommendation for this segment, from the BLM. The recommendation for this segment is discussed below. Justification for Instream Flow Increase The Blue Creek channel is large, with riffles typically ranging from 30 to 40 feet in width. The channel is also characterized by medium to large size substrate, which tends to reduce water velocities. Substantial flow rates are required to maintain sufficient depth and velocity for salmonids in this type of environment. According to the data collected by BLM, the current instream flow water right is capable of meeting 2 of the 3 instream flow criteria during the winter. However, the current instream flow water right is not capable of meeting 3 of 3 instream flow criteria during summer, when the fish population requires more physical habitat for foraging, weight gain, and preparation for overwintering. If the current instream flow water right were to be experienced during snowmelt runoff, less than 2/3 of the active stream channel would be wetted. With this reduction in physical habitat, the creek would not be able to sustain the fish biomass it sustains today. BLM believes that the reason that the creek supports a healthy and productive fishery is that the creek consistently experiences significantly more water than the current instream flow appropriation. During the warm weather period of May through October, spot flow -2-