From The Grand Junction Daily Sentinel (Dave Buchanan):
The day-long seminar brought an estimated 100 people to hear a lineup of geologists, biologists and water and soil specialists discuss the difficulty of managing selenium, a naturally occurring mineral found in high concentrations in Mancos Shale. It’s estimated the selenium-rich Mancos Shale in the Gunnison River Basin and the Uncompahgre Valley accounts for 61 percent of the selenium deposited in Lake Powell each year, said Sonya Chavez de Baca, task force coordinator.
Denis Reich of the Colorado State University Extension Service in Grand Junction showed a Google Earth map showing selenium concentrations in the Uncompahgre Valley. Although most of Uncompahgre Valley is an area of concern, “Loutzenheizer Arroyo (near Delta) is considered the largest concentration of selenium in the Uncompahgre area,” said Reich. “If we could find a way that allows us (to cut down selenium contributions from the Uncompahgre Valley), that would go a long ways to solving the selenium problem in the Colorado River,” Reich said.
Land use change, particularly when previously unirrigated lands have water put on them, is a big contributor of selenium to the waterways, said David Dearstyne of the Natural Resource Conservation Service. An example is the development of unfarmed lands around Montrose and Delta, where lawns, ponds and septic systems now are putting water on selenium-rich soils…
…managing selenium is important, Osmundson explained, because it accumulates and causes defects and reproductive problems in fish and wildlife, including endangered native fish in the Colorado River.
One way to manage selenium transportation in irrigated fields is lining ditches to prevent seepage into deeper soils where selenium is found. Ditches were lined in the Grand Valley starting in 1988 through the Colorado River Salinity Control Program. There currently is no federal program to deal with selenium but lining ditches to control salt transport and leaching also controls selenium. The Uncompahgre Valley Water Users Association is lining ditches in the area it serves, said association manager Marc Catlin, but it’s very expensive.
More water pollution coverage here.