Tuesday, October 11, 2011

LGA Completes Indian Brook Project

A multi-year project to protect the upstream waters of Indian Brook has been completed by the Lake George Association (LGA). The project is located at the intersection of Federal Hill and Sawmill roads in the town of Bolton.

Over a number of years, a small section of Indian Brook started to collect sediment in an area that was once a swimming hole. Eventually the swimming hole completely filled in, and non-wetland vegetation became established. Without the swimming hole to slow the velocity of the water, the brook started to carry more sediment downstream and into Lake George, contributing to a delta at the mouth of the brook.

In 2009, the LGA cleaned out the swimming hole. Approximately 500 cubic yards of material were removed. In the spring of 2010, native shrubs were planted along the bank to filter storm runoff. The former swimming hole is now functioning as a sediment basin, allowing sediment that is carried during high flow periods to swirl around and drop out of the stream. The sediment remains in the basin and does not flow down to the Lake.

This summer the LGA completed construction of a second sediment basin, a little further upstream from the original. “Our goal with this second project was two-fold,” said Randy Rath, LGA project manager. “One, create an offline basin that will capture and settle out suspended material during storm events. Two, enhance an existing wetland area and use the natural process of wetland formation to remove some nutrients present in the water column.”

“The wetland area is actually more like a sand bar,” Rath said. “It was originally formed during the 2005 storm event that brought about 7” of rain and washed out many roads in the Bolton area. During the storm, some finer material was deposited on the back end of the sandbar, and the area was eventually able to support wetland vegetation.”

LGA Education Director Emily DeBolt selected plants to match wetland species already present in the area. After installation by LGA staff, the wetland plants were given over a month to grow. With frequent watering from LGA staff and some timely rain, all of the plants and grasses survived a hot summer. Initially the wetlands were separated from the flow of the stream by sand bags and a straw bale dike. Fortunately the dike was not opened until after Tropical Storm Irene, and even though water overflowed the dike during the storm, the basin and wetlands remained intact, and continue to function as designed.

A third component of this Indian Brook project included roadside drainage improvements. A roadside ditch was stabilized and several check dams were put in place to slow the stormwater flow running down the shoulder of Federal Hill Road. A small basin installed at the end of the ditch captures the flow and allows sediment and debris to fall out. Additional road shoulder work allows for some stormwater sheet flow to occur over a vegetated area. The remaining shoulder work reinforced and directed the flow around a bend in the road to another small basin that captures the stormwater.

“Now with these essential upstream projects complete,” Walt Lender, LGA Executive Director, said. “We expect to see a dramatic reduction in the growth of the delta at the mouth of Indian Brook. The size of the delta that exists there now we know is not healthy for the Lake, and we are moving forward with our effort to remove this delta, as well as deltas located at the mouth of Finkle and Hague brooks,” he added.

Photos: Above, an area of Indian Brook earlier this year filled in with sediment; below, the same area of Indian Brook after a sediment basin and wetlands enhancement area was created.

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One Response

  1. Hamilton County SWCD says: