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More specific operational criteria for each key structure appear below followed by information <br />regarding Denver Water's operations with its reusable effluent generated with supplies from its <br />Southern System. <br />Northern System <br />1) Moffat Tunnel <br />Denver Water will only use transbasin water from the Moffat Tunnel and Dillon <br />Reservoir/Roberts Tunnel collection system after its direct flow rights on the South Platte River <br />have been used. Historical Moffat Tunnel supplies should be simulated in the SPDSS model <br />based on recorded historical diversions. Future supplies should be based on Denver Water <br />projections and/or the Upper Colorado River basin model. <br />Under the Consolidated Ditches agreement (Case No. 89SA345), Denver Water is able to make <br />up its evaporative losses from its mountain storage reservoirs in the South Platte River basin <br />(Antero Reservoir, Eleven Mile Reservoir, and Cheesman Reservoir) with Moffat Tunnel return <br />flows at the Metro and Littleton-Englewood WWTPs. The Consolidated Ditches agreement <br />identified only the effluent from those Colorado River basin sources used by Denver Water with <br />appropriation dates senior to May 1, 1940 that are dedicated to meet the high mountain storage <br />losses in the South Platte River basin. Denver Water cannot directly reuse transbasin deliveries <br />from the Moffat Tunnel except those derived from the Englewood-Ranch Creek portion of the <br />collection system. <br />The exchange to make evaporation replacements is not operated on a daily basis yet the long- <br />term average annual supply is greater than the losses from mountain reservoirs, according to <br />Steve Schmitzer with Denver Water. Evaporation replacement is addressed via gage height <br />operations whereby the reservoirs are able to maintain storage volume at the same gage height <br />over successive months. These replacements are not accounted against the storage rights for the <br />reservoirs and may require a new approach to modeling storage rights to represent these <br />operations in the SPDSS surface water modeling effort. One option would be to include a new <br />senior reservoir storage right to refill evaporation losses only that operates independent of other <br />storage rights assigned to the reservoirs. <br />2) Gross Reservoir <br />Gross Reservoir stores water under both its storage water rights and serves as the first storage <br />vessel for Moffat Tunnel deliveries. Water is delivered from Gross Reservoir to fill Ralston <br />Reservoir prior to December 15 each year. Denver Water has a 1998 agreement with the City of <br />Boulder to make a "good faith" effort to provide 2,500 ac-ft of storage space in Gross Reservoir <br />(Environmental Pool) as early and frequently as possible each summer. The Environmental Pool <br />is setup to be made available to the City of Boulder for storage and release of the City of <br />Boulder's water supplies. These supplies are projected to be used to make releases of up to 7 cfs <br />during the non-irrigation season to benefit South Boulder Creek stream flows down to the <br />confluence with Boulder Creek. The City of Boulder has not requested use of storage space in <br />Gross Reservoir since the 1998 agreement was signed. <br />Gross Reservoir may, at times, release western slope water in exchange for diversions on the <br />South Platte River at upstream locations. <br />Denver Water Board Operating Memorandum 35 of 40 <br />