Study reaffirms value of fresh water supply

The U.S. Geological Survey has confirmed what McCook residents remember every time they pay their city utility bills.

Fresh water is precious commodity.

New USGS research, comparing shallow groundwater quality beneath irrigated cropland in Nebraska, to similar water in Texas, reveals that concentrated contamination is more common in the Cornhusker State.

Scientists found that nitrate concentrations were higher and pesticides were more common in the Nebraska study area.

Nebraska nitrate concentrations ranged from 1.96 mg/L to 106 mg/L, and 773 percent of the samples had at least one pesticide, according to the USGS. In Texas, nitrates ranged from 0.96 to 21.6 mg/L and 24 percent of samples had at least one pesticide.

Why?

Part of the reason is crops -- mostly corn and soybeans in the north, and mostly cotton in the south.

And, according to USGS Hydrologist Jennifer Stanton, in Nebraska, "depths to water are less, precipitation is greater, evapotranspiration rates are smaller and recharge rates are greater in the northern study area than in the southern study area.

More than twice the amount of pesticides were applied to cropland in the northern study area than in the southern study area. Also, manure and commercial fertilizer application rates near monitoring wells were greater in the northern study area.

McCook residents know about nitrates -- the search for lower-nitrate city drinking water resulted in a 20-year odyssey that ended with a new state-of-the-art treatment system that uses reverse osmosis and filters to removes nitrates, arsenic and uranium from our city water supply.

The High Plains Aquifer, also known as the Ogallala Aquifer, is one of the nation's most important resources. It underlies parts of eight states, covering about 174,400 square miles from South Dakota to Texas.

But as our drinking water contamination experience proves, it isn't unlimited, nor indestructible. It's another resource that must be shepherded with care to remain available for generations to come.

Details of the U.S. Geological Survey study are available online at http://pubs.water.usge.gov/sir2006-5196/ and, hard copies of the report are available by sending an e-mail request to gs-w-nepublic-info@usgs.gov