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,,:;, .j >.J 1.._.-~ ",,", '.' ,-~, ~"'" such as the deletion of salvage of surface water, deletion of channel rectification of the Rio Grande, and a change in the method of stabilizing the surface area of San Luis Lake, have resulted in the preparation of this new environmental statement. These changes are primarily in response to the President's Executive Order l1990-Protection of Wetlands, Section 7 of the Endangered Species Act, and other environmental considerations (see section A-7). This final environmental statement (ES) is submitted in compliance with section 102(2)(C) of the National Environmental Policy Act of 1969 (NEPA) (Public Law 91-190) and in accordance with guidelines issued by the Council on Environmental Quality. This statement also complies with the requirements of part 516 of the Department of Interior Manual and part 376, chapter 5, of Bureau of Reclamation Instructions dated January 12, 1972, amended November 6, 1972, October 12, 1973, and December 17, 1975. A supplement to the final ES will be prepared prior to construction of Stage 3. 3. Description of project features a. Water pumping system. Pumping is expected to yield from about 66,000 to 104,000 acre-feet of water annually from the shallow unconfined aquifer. The project yield objective is 100,600 acre-feet. The shallow unconfined ground water (figure 1) is defined as that ground water which has a free water table and is not confined under pressure. In the project area, the shallow unconfined aquifer is encountered down to a maximum depth of approximately 135 feet. The deeper confined ground water is defined as that ground water under pressure significantly greater than that of the atmosphere. In the San Luis Valley, the confined ground water is contained in what is commonly known as the confined or artesian aquifer. The confined or artesian aquifer is separated from the overlying unconfined aquifer by the confining layer, which in the project area is about a 3- to 50-foot thick sequence of beds and lenses of tight, relatively impermeable sands and clays. In the project area, the top of the confined or artesian aquifer (at the bottom of the confining layer) is encountered at a depth ranging from about 75 to 160 feet. Figure 1 represents the general subsurface situation. ,;., ,f Pumping operations of the unconfined aquifer would be carried on through- out the entire year and would maintain the ground water levels at or below 8 feet from the ground surface within most of the project area. Well fields will be designed and pumping rates adjusted so that the '''~ A-6