Yankton Press & Dakotan

June 25, 2005

Study points to grazing management in increased sedimentation

Associated Press

YANKTON, S.D. - A new report shows poor grazing management is a bigger factor than tillage in increased sedimentation of Lewis and Clark Lake.

According to the study, feedlots or pastures where animals cross streams contribute more to the problem than cropland erosion, said Les Labaln, executive director of the Lake Andes-based Randall RC&D which conducted the study with the state Department of Environment and Natural Resources.

"It surprised me," said Labaln. "We didn't find any eroding cropland near the streams. Every field had good grass buffers. And all the towns had lagoons, and there weren't any factories along the rivers. It was all good."

The study showed sediment pollution most often occurs through bank erosion, river bottom disturbance and concentrated deposits of manure, all of which originate in areas with livestock, Labaln said.

The $300,000 study was paid for by donations from various organizations and governmental agencies. It focused on land that drains directly into Lewis and Clark Lake on the South Dakota side of the border.

Assessing the entire watershed, which stretches west from Yankton to Lusk, Wyo., will take much longer than the two years it took to complete the South Dakota portion, officials said.

John Deppe, executive director of the Mitchell-based Lower James RC&D, said the report gave officials insight into the future of Lewis and Clark Lake.

"There's a lot of sedimentation in the reservoir, and there seems to only be three ways to do something about it: Stop it from coming in, remove it or manage it," said Deppe, whose agency was a partner in the study.

Time is running out, said Deppe. Unless something is done, open water will be replaced by a massive sedimentation delta in the next 100 years or so, he said.

The process has already begun near Springfield, said Deppe.

Labaln said one challenge is to persuade farmers and ranchers to use better management practices. Also more research must be done to locate the exact acreage causing heavy sediment pollution, he said.

He said the goal of the study was not to create problems for farmers.

"We're actually trying to fix their problems and make them more sustainable," said Labaln.

Various organizations plan to start an education campaign on better management practices later this year. The goal is to tailor a program to fit each landowner's situation, Labaln said.