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. . l~ J. '-.ll. .J o.:lot>er 1996 Summary Sheet National Irrigation Waler Quality Program Uncompahgre Project and Grand Valley, Colorado LOCAL IRRIGATION HISTORY Irrigation began in the Uncompahgre and Grand Valleys of west em Colorado in the 1880's. Initially, individuals and private irrigation companies built the irrigation facilities. As the need for morc irrigation increased, the U.S. Congress passed the Reclamation Act of 1902. The Rcclamation Scr"ice (later renamed the Bureau of Rcclamation) began worb; on the Uncompahgre Project in 1904 and in the Grand Valley in 1912. Facilities such as the Gunnison Toonel and South Canal were constructed in the Uncompahgre Valley while lhc Cameo di,"crsion dam and Government Highlinc Canal were completed in the Grand Valley. The benefits of irrigation in these areas ha\'c been significant, provIding the basis for the agricultural economy that allowed both \"alleys to prosper. \Veil maintainc.d filffillands surround the cities of Grand Junction, Montrose and Delta adding to the qualityoflife. Howel'er, with these benefits, some associated problems del'e1oped which arc being addressed by local, state and Federal interests. The major concerns for water quality arc lhe large salinity contributions and high selenium concentrations. Additionally, endangered species hal'e been impacted by irrigation depletions and possibly, by thc water quality of Irrigation return flows PROGRAM BACKGROUND The concern with selenium contamination and its effects on the enl'ironment peaked in the 1980's because of occurrences at the Kesterson National Wildlife Refuge in California. Reclamation had built a large drain on the west side of the agriculturally rich San Joaquin Valley which terminated at a series of ponds in the Refuge Scientists originally looked at the quality of thiS water which was high in sahnity and declared it safe for \\.ildlife. However, they did not test for selenium. After just a few years of depositing this water into the Refuge, problems were discovered. Fish and Wildlife Service (F\\.'S) persoMel found many unhatched bird eggs and deformed young birds. Thc cause was determined to be high selenium concentrations in the birds and their eggs. The selenium had been leached by Irrigation water from selenium bearing shales wlthm the agricultural areas, carried to the ponds, and concentrated b)' evaporation. Because these problems were caused by a Federally constructed irrigation project, the Department of the Interior directed the U.S. GeologIcal Survey (USGS), F\VS, Bureau of Indian Affairs and Reclamation to Inl'cstigate other potential irrigation drainage related problems at Federal projects throughout the west This e(fort was named the National Irrigation Water Quality Program TilE LOCAL SELENIUM ISSUE High selenium concentrations hal'e been found In parts of the Uncompahgre and Grand Valle\"s which arc causing concern for local fish and wildlife resources. Selenium is a natura II" occurring clement found in trace amounts In our soils. It is vital to the health ofhumans,lt\-estock, fish and birds in ,'ery small amounts (parts per billion). Howe,'cr, problems can occur With exposure to just slightly higher levels For our fish and waterfowl that live in the aquatic em'ironment, selenium is an issue. Much of our irrigalion takes place on soils derived from and underlalO by the Mancos Shalc. Mancos Shale resulted from nlllllons of years or deposition in the anCient oceans that previously covered these arcas Besides dissoh'ing sailS in the Mancos Shale, the irrigation water also dissolvcs scleniunt "hich is carried by the ground water to drains, ponds,