Richard R. Roy T.F. O’Brien P. J. Blanchard 1993 Selenium concentrations larger than established standards and criteria were present in Gallegos Canyon and Ojo Amarillo Canyon drainages on the Navajo Indian Irrigation Project, a pond on the West Hammond Irrigation Project, and a drain on the Hogback Irrigation Project, New Mexico. Ground-water return flow from irrigated areas contributes substantially to surface water at these sites. Selenium concentrations in 11 surface-water samples from these four areas exceeded the State of New Mexico standard of 5 micrograms per liter for the protection of fisheries. Selenium concentrations in five bottom-sediment samples from three of these areas ranged from 4.5 to 38 micrograms per gram; the geometric mean concentration of selenium in Western United States soils is 0.23 microgram per gram. application/pdf 10.3133/wri934065 en U.S. Geological Survey, Water Resources Division ; U.S. Geological Survey, Books and Open-File Reports [distributor], Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in the San Juan River area, San Juan County, northwestern New Mexico, 1990-91 reports