SPOTTED HORSE, Wyo. — Most of Don Spellman's 8,000 acres in the Powder River Basin are rolling, treeless and, for the last several years, bone dry. But shimmering behind him as he drives fence posts into the hard-packed clay is a narrow, shallow lake that seems to spring from thin air.
The water, a byproduct of booming natural gas production in the Rocky Mountain West, is also host to millions of mosquitoes. And it may be the solution to a medical puzzle.
West Nile virus, which can sicken and kill people and animals, began its march across the United States in 1999. Scientists initially expected the disease, transmitted by mosquito bites, to stall west of the Mississippi, where sources of standing water are scarce.
Instead, it has thrived. Ten of the states with the most illness per capita are west of the Mississippi. Eight are in a prolonged drought.
Four -- Wyoming, Colorado, Montana and New Mexico -- are experiencing a boom in natural gas production. The gas is forced out of underground coal beds by pumping millions of gallons of underground water to the surface. The process leaves warm, shallow ponds -- ideal breeding grounds for mosquitoes -- scattered across the usually arid landscape.
Scientists studying the infection are not yet ready to declare the case closed. But as researchers trace the possible link between natural gas production and the illness, places such as Campbell County in northeastern Wyoming, which has nearly 13,000 coal bed methane wells, have become open-air laboratories.
This summer, researchers from two universities are testing water sources in the region, including natural gas discharge ponds, for mosquitoes that spread West Nile.
There are thousands of such ponds in Campbell County -- one of the driest in Wyoming. Last year, the county of 33,600 people recorded the state's second-highest number of cases of West Nile infection, with 66. Wyoming had 373 human cases in 2003, the sixth-highest rate in the nation.
Coal bed methane wells are by no means the only source of standing water in a region that depends on widespread crop irrigation. But in Campbell County and the surrounding Powder River Basin, gas production pumps out 60 million gallons of water a day, outstripping agriculture's contribution to standing water.
Moreover, hydrologists note that -- unlike seeps, springs and irrigation ditches -- discharge ponds related to natural gas production are present even in the dry summer months when other standing water often evaporates.
