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Options considered but not evaluated further <br />Water conservation: Irrigation canal check structures, ditch lining, and conversion to more efficient <br />irrigation methods (e.g., from flood to sprinkler irrigation) were considered. Although such <br />measures appear to have a favorable cost-benefit ratio, they would provide less water during periods <br />of severe or prolonged drought than the firm yield from reservoir storage. Moreover, conversion to <br />sprinkler irrigation on the large scale necessary to meet the instream flow augmentation requirement <br />would result in drying up some wetlands that rely on return flows from flood irrigation. However, <br />conservation measures could be used in conjunction with a firm reservoir water supply to enhance <br />the performance of both. <br />Winter/off-peak stora�e: Under this option, water would not be stored during the spring peak-flow <br />period, but would be stored in winter or during other off-peak periods. Such an option may require <br />diversion(s) from the mainstem of the Yampa River into a tributary reservoir, since a mainstem dam <br />would have unacceptable adverse impacts on the Yampa River, and most tributaries to the Yampa <br />do not have enough off-peak runoff to support the entire volume needed. This option was rejected, <br />in part, due to its potentially high cost but, mostly, because it may call for water to be stored during <br />the same period when augmentation normally would be needed. <br />Proposed action for augmentation water supply <br />The proposed action to enlarge Elkhead Reservoir was selected over other alternatives because it <br />better meets the primary objective of the action (i.e., providing 7,000 AF of water for base-flow <br />augmentation) than any of the "non-structural" options (i.e., no action, instream flow water rights, <br />supply interruption contracts, water conservation). Moreover, water deliveries from Elkhead <br />Reservoir would be more reliable, would suffer less transit losses, and would be less difficult to <br />administer than deliveries from reservoirs farther upstream (Steamboat Lake, Stagecoach Reservoir). <br />Enlarging Elkhead Reservoir is more cost effective than constructing a new reservoir, and it will <br />avoid undesirable impacts to state parks that would likely result from similar projects at Steamboat <br />and Stagecoach. The proposed joint expansion of Elkhead Reservoir to serve the needs of both fish <br />and people further reduces the unit cost for both. <br />Categorically excluded actions and actions addressed in a separate NEPA document <br />Certain actions proposed for implementation under the Yampa Plan, such as monitoring populations <br />and habitat, are categorically excluded for the purposes of the NEPA (see EA beginning on <br />page 108); whereas the impacts of other actions, such as acquiring, restoring, protecting and <br />maintaining floodplain habitats, have been addressed in a previous NEPA document (USDI 1998). <br />Site-specific impacts to wetlands due to expansion of Elkhead Reservoir also will be addressed in <br />greater detail in a separate EA prior to the Department of the Army issuing a permit for the project <br />under §404 of the Clean Water Act. <br />Finding of No Significant Impact 3 <br />