San Juan Dolores Draft Instream Flow Recommendation

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Dolores River Lower Terminus:Confluence with West Creek 3,000 2,500 loam Combined(1984-2012)25th to 75th percentile , -Combined(1973-2012) 0 2,000 r e -Combined (19842012) � a "' 1,500 - - . . .._.. ... ,..,: y.. _.__ _. .___ —Combined(2000-2012) -Original lSF 1,000 � ya r ----Adjusted i5F try is l' 4 500 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec The initial analysis of water availability revealed that proposed instream flow rates are conservative, when viewed from the perspective of water availability: • The proposed flow rates are available at least 50% of the time, when viewed from the perspective of median flows over a wide range hydrologic conditions between 1984 and 2012, since the Dolores Project has been constructed. • The proposed flow rates leave a substantial volume of water available in the river for future development, when viewed from the perspective of median flows. During the peak snowmelt period from April 15 to June 15, it is estimated that the proposed flow rates would leave more than 66,000 acre feet available for development. During the baseflow period from August 15 through March 14, it estimated that the proposed flow rates would leave more than 23,000 acre feet available for development. • Even when viewed through the perspective of the recent drought period from 2000-2012, the proposed flow rates are generally aligned with water availability. There are certain short periods during drought years, such as late April and early June, when there would not be sufficient flow available to meet the recommended flow rates. However,the BLM and CPW believe that the opportunity to protect flow during the critical April 15 to June 14 period during average and above average years is important to long-term health and viability of this population of the three sensitive species. • During drought years, it is likely that the proposed junior instream flow water right would not be in priority during the entire April 15 to June 14 period. Accordingly, the instream flow water right would not prevent diversions by established and critical water uses during drought periods. In addition,the instream flow water right would be junior to a large number of existing conditional water rights that have not yet been developed. • If the period from 2000 through 2012 is viewed as a representative drought period,the proposed flow rates still allow for future water development by new junior water rights that could be established after an instream flow right is decreed. During the base flow