In increments as small as three square meters or as large as 30 square miles, a new software tool developed by the Wisconsin Department of Natural Resources promises to help reduce agricultural runoff and erosion.

Developed to integrate satellite imaging and geographic information system or GIS technology, the erosion vulnerability assessment for agricultural lands tool — known as EVAAL — clearly depicts areas susceptible to runoff based on topography, land cover and soils. While the software will be used by environmental professionals ranging from consulting engineers and nutrient management planners to county conservationists and academic researchers, it is expected to produce very real benefits for citizens statewide.

“We know clean rivers, lakes and streams are a priority for Wisconsin residents,” said Theresa Nelson, a water resources engineer in the DNR division of water quality. “Reducing agricultural runoff conserves topsoil and cuts down on the amount of phosphorus entering our surface waters. The new software helps prioritize lands with the greatest vulnerability, saving time and money for farmers by identifying the most significant opportunities to cut sediment and phosphorus runoff.”

Detailed maps produced by the software highlight areas where large gullies or tiny rills may carry nutrients away from fields and toward bodies of water. Other elements, such as large internally drained areas that help capture runoff also appear. The EVAAL tool allows private landowners and county planners to consider these features at both the grid scale — down to three square meters — and at the broader field or watershed level.

“Modern farm technology allows for the precise application of nutrients down to the grid level, but until now, these grids accounted for soil quality rather than differences in topography and the potential for water movement,” Nelson said. “With the EVAAL tool, practicing precision agriculture becomes an opportunity to achieve precision conservation. Beyond identifying simple changes, such as slightly expanding a buffer area or adding vegetation to a gully, the software allows for broader efforts aimed at improving a watershed.”

Phosphorus has long been recognized as the controlling factor in plant and algae growth in Wisconsin lakes and streams. Small increases in phosphorus can fuel substantial increases in aquatic plant and algae growth, which in turn can reduce recreational use, property values and public health.

Greg Baneck, county conservationist with Outagamie County, said his team has been using an early version of the EVAAL software for several months in their efforts to develop a plan that addresses nonpoint source pollution issues.

“The maps and data produced by the program allow us to focus our efforts and work more efficiently than ever before,” Baneck said. “This is a huge benefit with limited staffing resources, helping us to assist the landowners who need it the most.”

Nelson said the new software is available for download by visiting and searching for “EVAAL.” The package includes methods documentation, a tutorial and practice datasets.