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('\J '\;11 ;".'\") .,.-i c..:. 1:->; RrI'LY RHIR TO: Colorado Water Conservation Board 823 State Centennial Building 1313 S~erman Street Denver, C6lorado 80203 ATTN: J. William McDonald, Secretary United States Department of the Intcrlll!- BUREAU OF RECLAMA TION SAN LUIS \' ULEY PROJECT 715 SIATH STRlET - BOX 44. ALAMOSA. COWRADO 81101 'SEP 2 2 1982 Dear Sirs: In October the Bureau of Reclamation will be asking for concurrence for the start of Stage 3 construction from the Rio Grande Water Conservation District and the State of Colorado Water Conservation Board, as required by Section 101 (b) of Public Law 92-514 (86 Stat. 964), the authorizing legislation, .as amended by Public Law 96-375 (94 Stat. 1507). . Our plan of development provides for stage development of project features over an 8 year period and provides assurance to local and State of Colorado interests that pumping of the shallow ground water will not adversely affect ground water conditions in the valley. The Definite Plan Report, page B-6, gives a range, 13,000 to 23,000 acre-feet per year, ground water yield estimate for Stage 1-2. Completion of salvage wells in Stage 1-2 showed that this stage will produce about 14.000 acre-feet per year. Our well spacing model and Geologic survey's computer model shows pumping at this rate will not violate any boundary conditions as required by the amended legislation. Based on water samples from the salvage well drilling program in Stage 1-2, un- confined ground water has a combined mixed total dissolved solids content of 149 parts per million (ppm) and a combined mixed sodium ion concentration of 30 percent of the total positive ions. This water quality is well within Article III of the Rio Grande Compact requirements. Regulation of standards promulgated pursuant to the 1965 Water Quality Act are administered by the concerned states and overSeen by the Environmental Protection Agency. The Denver Engineering and Research technical water quality staff reviewed the "Classification and Numeric Standards" proposed by the Colorado State Health Department Water Quality Control Commission. The Denver technical staff concluded that if the water sampled is representative of water to be salvaged and discharged into the Rio Grande. the blended water should meet all the pertinent numeric criteria. The Project Office is analyzing. water from Stage 1-2 for trace elements. e.g., cadmium, copper, lead, mercury, silver, and iron and have found no violations to Colorado's numeric standards. Our specifications design exploration data indicated a thin membrane lining would be the most economical approach for the canal. This membrane lining would reduce channel leakage and water quality problems that could arise from an unlined channel.