land-use

The presence of nitrates in drinking water is a pervasive concern in semi-arid and arid regions in Arizona, much of California, the Midwest region and large areas in the South despite government regulations.

Part of what is driving the problem is that water managers and urban planners in certain regions prone to nitrate contamination don't always have adequate information about sources of nitrates and ways to control or manage the chemical's presence.

The Walnut Gulch Experimental Watershed surrounds the historic city of Tombstone in southern Arizona. The USDA - Agricultural Research Service established the watershed in the 1950s to study floods and the impact of soil and water conservation projects on runoff.