CRWD works to stabilize creek’s bank

Published 10:52 am Friday, August 19, 2011

Area conservationists are using a technique to fix small, nearby rivers, and that may someday have a larger effect downstream.

Throughout this week, Justin Hanson of the Cedar River Watershed District along with a crew of excavators repaired a section of Dobbins Creek near Brownsdale. But it’s the method they are using that could someday reduce turbidity (dirtiness) of the water. Hanson and the crew cut small unnecessary trees from ditches and anchored them into the bank with a backhoe.

Conservationists are using this method, called a tree revetment, where sections of streams continuously erode and cause dirt and excess sediment to raise nutrients and turbidity in the water.

By burying the 8- to 10-foot trees into the bank — forming a wall — the river will one day repair itself, according to Hanson.

“The idea is: They actually stabilize the bank, and then the sediment sets out behind them an eventually fixes the stream-bank erosion problems,” he said.

Though other counties have used the method for about a decade, CRWD officials are jumping on board because the method could have long-term, positive effects downstream if conservationists do enough of these projects.

For now, CRWD officials and excavators are using the method on a small scale as it is easier for them to track the benefits.

���If you get in on a small enough scale, then you can measure the results,” Hanson added.

Traditionally, large rock piles have been used to protect banks from erosion; however, the tree revetment offers two more benefits. It’s cheaper than piling rock, and it one day becomes part of the natural landscape. Hanson said over time, the trees absorb the sediment and become stronger. As a result, the trees naturally heal the bank.

“If we can figure out a way of doing green or natural ways to do restoration projects, I think it’s better for everybody, better for the environment,” Hanson said.

The will finish the project on Friday and measure the future results. Hanson said if enough of these projects show significant improvements, the process could be used on a larger scale, such as the Cedar River.