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Muddy Creek is nondescript, a narrow stream trickling through thesagebrush steppe of southern Wyoming. But like many Westernwaterways, it carries selenium, a natural poison that seeps fromrocks and dirt and accumulates in the food chain much as mercurydoes. Both humans and animals need tiny amounts for good health, but toomuch is dangerous. In areas with a lot of selenium in the soil,including Utah's Middle Green River Basin and Nevada's StillwaterNational Wildlife Refuge, activities that bring soil into contactwith water -- irrigating, mining, drilling and road building --boost natural concentrations, and can cause illness and deformitiesin people, livestock and wildlife. Now, researchers are studying the Muddy Creek watershed, trying todetermine how much of the element occurs naturally, and how much isbeing released by human activity. Tracking selenium sources in thisway is tricky, but essential; few studies have examined whereselenium comes from and where it ends up. JoAnn Holloway, a physical scientist with the U.S. GeologicalSurvey, and her team of researchers have tested for selenium inwater, soil, rocks and invertebrates in this part of the ColoradoRiver's upper tributaries for several years. The team has setbaseline data for the region, measuring background levels andinvestigating whether recent local natural gas development isincreasing amounts, as erosion from newly scraped roads and wellpads washes selenium into streams. By studying the watershed now,prior to extensive development, Holloway's team may help landmanagers ward off potential problems. "Selenium is going to becomean issue (as energy development continues)," says Holloway. "Ourstudy was a way of saying, We need to keep our heads up aboutthis.' " The USGS, the Bureau of Land Management and the U.S. Fish andWildlife Service all watch for selenium pollution in various ways,but no agency has clear responsibility for comprehensive West-widemonitoring. The Environmental Protection Agency has regulatedlevels in drinking water since the 1970s, but has yet to developrules limiting significant sources, such as coal ash produced bycoal-fired power plants. For years, selenium was often overlooked as an environmentalproblem. Then, in the early 1970s at Kesterson Reservoir inCalifornia's San Joaquin Valley, a Bureau of Reclamation projectbegan dumping irrigation water, carrying selenium leached from farmfields into wetlands. By the early 1980s, fish, birds and reptileswere failing to hatch or had serious deformities missing eyes,misshapen beaks, protruding brains. "That's a sort of worst-casescenario of how nasty selenium can get," Holloway says. Irrigationis still a major source of selenium pollution in Western waterways. It made hair-raising headlines again this February. Photographs ofdeformed trout, some two-headed, surfaced from a study commissionedby the J.R. Simplot Company, which wants to release selenium atlevels above national and state standards at its southeastern Idahophosphate mine. The U.S. Fish and Wildlife Service concluded thatSimplot's report systematically underestimated the impact onwildlife. (The company's request is still pending.) The reproductive abilities of native fish such as razorback suckersand Colorado pikeminnow are already limited by selenium in theColorado River watershed. After hatching, the poorly developedoffspring are likely to sicken or be eaten. "These are fish thatevolved to live in these waters," says Ken Leib, a hydrologist forthe USGS. "Current selenium levels are probably higher than theywere historically." But quantifying selenium increase at a single location isn't easy.Selenium levels vary seasonally and annually, depending on waterflows, and data on historical background amounts are thin tononexistent. Distinguishing natural levels from development-causedones is, says Holloway, "kind of a dicey operation." It's easier tostudy contaminants that don't occur naturally, such as pesticidesor dyes. At Muddy Creek, Holloway's team found no clear uptick in seleniumconcentrations in developed versus undeveloped areas. That may bedue to the relatively short monitoring period. However, the teamdid find that the creek's aquatic and riparian invertebrates --damselfly larvae and long-jawed spiders -- are accumulating moreselenium than is considered safe for the birds and fish that feedon them. This link, demonstrating how water quality affectsselenium levels in the food web, is the study's key finding, saysPatrick Lionberger, a fisheries biologist at the Rawlins BLM fieldoffice. While it's too early to say how the study might affect energydevelopment permitting, Lionberger says it does give the BLM moreto consider in the approval process. If a strong link betweenselenium concentrations and energy development is established,state and federal regulatory agencies might decide to change landmanagement practices. The BLM won't comment on possible changes,but Holloway's study implies that they might potentially includesome limits on road and well-pad building; the state couldpotentially restrict surface discharge of the water produced bydrilling. For now, reluctantly, Holloway's USGS team has had to quitgathering data -- they ran out of funding. But even as researchproceeds in fits and starts, the West's selenium issues are likelyto become more severe. "The big issue here in Muddy Creek and inthe West in general," says Travis Schmidt, an invertebrateecologist on Holloway's team, "will be, I think, the cumulativeeffect. We're changing the way we use land, and there is no bigeffort to monitor the effects of selenium on downstream resources.Over the total landscape that could be a huge problem forwildlife.". 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