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' <br />' <br />' <br />' <br />Based on available information reviewed for this study, site reconnaissance, and experience with other <br />' dam sites in similar geologic settings, it does not appear that there are any fatal flaws to the construction <br />of an earth dam at the proposed Grand Valley Dam and Reservoir site. <br />Reservoir Yield Analysis <br />The annual yield of Grand Valley Lake that could be delivered every year was estimated using a <br />reservoir operations model developed in Excel for a study period of 1975 through 2005. This period <br />contains at least one short intensely dry year (1977) as well as a more sustained drought (2001 through <br />2004). In general, reservoir yield is a result of the interplay among the water supply (inflow) time series, <br />the demand or release (outflow) time series, and the capacity of the reservoir. Two reservoirs of different <br />capacity were analyzed: a 154,500-af reservoir (Alignment 1), and a 39,800-af reservoir (Alignment 2). <br />The inflow and outflow time series for the analyses are described below. <br />According to the model, annual (1975 — 2005) physical flow at the Lazear gage averages 1.14 maf, of <br />which 1.02 maf is available to a junior right. Water is least available from January through March, and is <br />also unavailable in late summer of dry years (1977, 1990, and 2002 through 2004). May and June <br />available flows often exceed 100,000 af and can range over 600,000 af, greatly exceeding the range of <br />likely diversion capacities (200 — 400 cfs, or approximately 12,000 — 24,000 af/month) for the canal. <br />An example composite demand on the large reservoir (Alignment 1), assuming releases of 150,000 <br />af/yr, is shown in Figure E1. In wet and above average years, the Fish Release (salmon color) is not <br />made. The shape of the composite demand pattern and the proportion assigned to each use in a given <br />month vary with the annualized demand, because irrigation use is always preserved, regardless of the <br />yield being tested. <br />AECOM <br />2/22/10 <br />