Targeting conservation where it's needed most

Everything about any given part of a landscape affects how much water and water-borne pollution flow off the land and into nearby lakes and streams.

Is the land hilly or flat? Does water rush off it or slowly sink in? Is the land close to surface waters or far away? How have we humans used that land? Have we paved over it? Are we cultivating it in ways that encourage erosion or ways that keep soil in place?

And are there conservation practices that if we put them in place at a particular spot on the landscape will give us a better return on our investment than similar investments elsewhere?

Those are the kinds of questions asked – and often answered – by precision conservation, one of the hottest current topics in conservation and water planning.

Did you miss the conference
on precision conservation
or want to share what you learned
with colleagues? All the
presentations are archived on
YouTube videos.

This spring, the Freshwater Society and a number of partners sponsored a conference that drew about 165 people for some engaging presentations on emerging high-tech methods of identifying sweet spots on the land where runoff and erosion are especially severe and the potential for improving water quality is especially great.

“Precision conservation is the tool that we’re trying to develop to get a bigger bang for the buck in terms of spending money on conservation practices,” David Mulla, a University of Minnesota soil and water scientist, told the crowd. “This allows small portions of the landscape that have a disproportionately high impact on water quality to be targeted with best management practices.”

In addition to focusing on the technology for finding those sweet spots, the conference dealt with research on why land owners do, or do not, adopt voluntary conservation practices, and on what conservation professionals can do to persuade land owners.

David Mulla
David Mulla

“It really does come down to relationships,” said Paul Nelson, natural resources program manager for Scott County and administrator for the Scott Watershed Management Organization.

Nelson said conservation workers must earn the trust and respect of landowners and then persuasively invite the landowners to adopt practices that protect soil and water.

Mulla, an expert in the related fields of precision agriculture and precision conservation, gave the lead presentation at the conference.
“When we look at precision conservation, we’re trying to evaluate, not only what’s good for production, but also how we can optimize the environmental benefits of whatever we’re doing,” Mulla said.

As an example of disproportionalities in pollution, Mulla cited 2005 research on the Le Sueur River Watershed in southern Minnesota.
The Le Sueur Watershed covers only 7 percent of the land in the Minnesota River Basin, he said. But it contributes 53 percent of the sediment, 31 percent of the phosphorus and 20 percent of the nitrates flowing down the Minnesota.

Mulla outlined the use of LiDAR – Light Detection and Ranging – technology as a key means of efficiently and effectively identifying targets for conservation practices that will yield disproportionate environmental benefits.

LiDAR is a terrain-mapping technology that uses billions of laser beams shot at the Earth’s surface from low-flying planes. Measuring the speed of the rebounds from those beams produces computerized maps of elevation and drainage that are much more detailed than any maps previously available.

The improved maps allow a water planner sitting at his or her computer to quickly scan large landscapes, looking for places on the land where the combination of a large drainage area and a significant change in elevation creates potential for fast-moving water and erosion.
As an example, Mulla cited a 2005 evaluation of Seven Mile Creek in Nicollet County. Kevin Kuehner, then an employee of the Brown Nicollet Cottonwood Water Quality Board, walked the creek with two colleagues, measuring elevations, noting the places where erosion was occurring and calculating the potential soil loss at those sites.

A few years later, Mulla directed research that replicated Kuyner’s evaluation of the creek through analysis of LiDAR-based maps. The computer analysis found most of the same points of erosion that Kuyner had found – at huge savings in cost and time.

“This is a very cost-effective way of identifying critical areas,” Mulla said.

Nelson, the Scott County natural resources manager, took part in a joint presentation with Mae Davenport, a University of Minnesota professor in the human dimensions of natural resources and the environment who has researched what motivates land owners to practice conservation.

Two big factors for those adopting conservation measures, she said, are they want to be respected and recognized for their efforts and they are responding to a request from someone they know, respect and trust.

Two reasons landowners may reject or put off conservation, she said, are they don’t know what to do or they are not convinced their actions will make a difference.

Did you miss the conference on precision conservation or want to share what you learned with colleagues? All the presentations are archived on YouTube videos. To find links to all the videos, go to and search for Precision.





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