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<br />MAY 1982 <br /> <br />Because of several factors, water. quality in McElmo Creek is poor. <br /> <br />Studies by the Bureau of Reclamation indicate that return flows from <br /> <br />irrigation and the presence of the Mancos shale formation in the drainage <br /> <br />area contribute to high salinity concentrations, averaging 2,650 mg/1 near <br /> <br />Cortez and 2,880 mg/1 near the Colorado-Utah State line. The overall <br /> <br />quality of the stream varies considerably because of fluctuations in the <br /> <br />volume of the return flows. Overall, the water is very saline, and quite <br /> <br />hard. The high levels of dissolved salts, turbidity, and temperatures <br /> <br />create a harsh environment for fresh water fish and invertebrates. Flow in <br /> <br />Navajo Wash is derived primarily from irrigation return flows during <br /> <br />much of the summer and fall, and both the flow and turbidity fluctuate <br /> <br />often, even within the same day ~/. The quality of the water is generally <br /> <br />poor. Samples collected by the Hureau of Indian Affairs since 1968 have <br /> <br />shown salinity concentrations ranging from 6,330 mg/1 during low flows to <br /> <br />1,980 mg/1 during high flows. <br /> <br />Ground Water Quality <br /> <br />Salinity concentrations of ground water in the MontezuQa Valley vary <br /> <br />from about 250 to 3,000 mg/1. In the lower elevations of the McElmo Creek <br /> <br />area it varies from 1,000 to 3,000 mg/1. <br /> <br />Land Ownership <br /> <br />Irrigated agriculture is well suited to the area with an estimated 29,100 <br /> <br />acres of irrigated cropland presently in the study area. The median size of <br /> <br />irrigated farm is 85 acres. The average overall per acre value of farmland <br /> <br />in Montezuma County is $427 ~/, with irrigated cropland ranging from $1,000 <br /> <br />to $3,000 per acre. The per farm market value of products sold is $20,533. <br /> <br />The number of farms by value of sales are as follows: <br /> <br />~/ Buddy Lee Jensen, Fishery Management Biologist, Dolores Project <br />Investigations: Ute Mountain Indian Reservation, Colorado and New Mexico <br />(U.S. Fish and Wildlife Service: Gallup, N. Mex., January :W(\ '~j . <br />~/ Bureau of Census, 1978 Census of Agriculture Colorado, U:-s.~ &epartment of <br />Commerce. <br /> <br />III-ll <br />