July 23, 2010Vol. 12, No. 7

Barriers in the "Not-so-Wild"

An old, metal culvert is "fixed" by the insertion of a smaller plastic culvert.

by Dale Finseth

Before starting this week's article, I downloaded a couple of pictures for inspiration. Both are from a watershed survey the Kennebec District did last spring. One shows an old metal culvert, crushed but still in use. The other is a classic metal culvert which has been "fixed" by being slip-lined with a smaller plastic culvert and then with expandable foam added between the two culverts in order to hold the entire contraption together. I try to look at these water conveyances as a brook trout or other form of aquatic life would. It isn't a good view! They look like barriers to me.

The Kennebec District is currently involved in a rather large culvert/stream barrier survey in the lower portion of the Kennebec River watershed. We have partnered with the Kennebec Estuary Land Trust, the Androscogggin Valley Soil & Water District, and the Sheepscot River Watershed Council in an effort to survey all road crossings and document how the water gets from one side of the road to the other. Take a look next time you are driving along or taking a walk and you will realize that the methods vary.

Ideally the water travels slowly enough and through a wide enough channel to maintain an environment conducive to fish passage and all the other aquatic critters that may move up and down streams. While we usually focus on fish, there are all kinds of other critters important to stream and pond health. And that means water quality.

What do we find? Sometimes the road crossing is a bridge. Often that is better than a culvert because the water flow is more gradual and the stream bed beneath the bridge is closer to a "natural" channel. Usually it is a culvert. Frequently they are so small and/or steep that wildlife is unable to travel up them. Or they may be so damaged that most critters, and certainly fish, can't travel through them. Or the classic a culvert where the water runs out the lower end, drops a couple feet and scours out a large hole beneath the outlet.

Unfortunately the "fix" for such barriers is usually replacement. The replacement is nearly always much larger and installed deeper. Replacement is expensive. The improved life span of the properly sized culvert makes the cost more realistic. The vast improvement for aquatic plants and animals up stream can be priceless!

Most of this culvert survey field work will be done this summer. We hope to work with others and replicate the survey further north in both the Androscoggin and Kennebec River watersheds. The results can help guide construction and planning decisions at local, State and the Federal levels.

Remember . . . the objective is improved water quality and native plants and animals are a big part of that.

Dale Finseth, Art Grindle, and Josh Platt work for the the Kennebec County Soil & Water Conservation District in Augusta. For more information about the district and its projects, one may call them at 622-7847, X 3 or visit www.kcswd.org.