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HARZA has concluded that the benefits obtained from any modification to the outlet tunnel <br /> below the downstream gates would be small in relation to the cost, create unknown and potentially <br /> unsafe seepage conditions at the toe of the dam, and only result in a small amount of additional <br /> discharge capacity. Finally, HARZA has advised the District and the State Engineer that safe <br /> operation of the Reservoir's current outlet works requires that,except in extreme circumstances,the <br /> tunnel not be pressurized and that the releases through the downstream gates be managed so as not <br /> to create turbulent hydraulic conditions. <br /> Due to the importance of the Reservoir and the historical structural limitations of the outlet <br /> works, the State Engineer and the District are entering into this Memorandum of Understanding to <br /> establish procedures to accomplish safe operation of the Reservoir. This Memorandum of <br /> Understanding establishes recommended operating principles for the Reservoir which will promote <br /> dam safety, prevent damage to the Reservoir outlet works, protect downstream water rights, and <br /> ensure that the State can continue to meet the Rio Grande's separate Compact obligations. <br /> RESERVOIR OPERATION <br /> 1. Releases from Rio Grande Reservoir <br /> When the Reservoir is not lawfully entitled to store water, releases of Reservoir inflow will <br /> be made in the following order as conditions require and in coordination with the Division Engineer: <br /> Step 1: The Reservoir's downstream gates will be used to make releases up to a <br /> maximum rate of approximately 1,500 cfs. <br /> Step 2: Inflows over approximately 1,500 cfs will be held in the Reservoir up to the <br /> spillway crest at elevation 9,449 feet, so long as demand of downstream <br /> senior water rights is met with existing streamflows or by the implementation <br /> of one or more of the steps described in paragraph 2 below. <br /> Step 3: If the demand of downstream senior water rights cannot be met under Step <br /> 2, then outlet releases will be increased to 2,500 or such lower rates as will <br /> meet downstream demand and maintain stable hydraulic conditions in the <br /> outlet tunnel. <br /> Step 4: When the Reservoir is full (elevation 9,449 feet), inflows will be allowed to <br /> flow over the spillway up to a depth of three feet,being elevation 9,452 feet. <br /> At elevation 9,452, approximately 2,300 cfs is spilling with a concurrent <br /> release through the Reservoir's outlet of 1,500 cfs. <br /> Step 5: Anytime the Reservoir level exceeds 9,452 feet in elevation and there is a <br /> senior downstream call, the release through the gates will be increased to <br /> 2,500 cfs or such lower rate as will meet downstream demand and maintain <br /> Page 2 of 5 <br />