Monday, June 27, 2011

Dams, Culverts and Stream Crossings, Oh My!

River Herring (a.k.a Alewife)
Alosa pseudoharengus
their life in the ocean and
travel up rivers to breed.    

Imagine being a river herring. After spending a few years growing up in the Atlantic Ocean, it is time to return to the river you were born in. Your senses bring you back to the mouth of the Pawtuxet River where you swam out into the Narragansett Bay, tasting saltwater for the first time, just a few short years ago. You are ready to return to your hatching grounds with your school so you can repeat the process like so many ancestors before you.
The portion of Pawtuxet Falls Dam you see
here is slated to be removed this summer. The
removal will restore the connectivity of the river
to the Bay, and minimally decrease flooding in the area.

But to your dismay, a huge waterfall pours down in front of you (remember, you are a fish, less than a foot long). You cannot jump over the dam, and you cannot swim around it. Just then a large blue bucket scoops you out of the river. You sit in the bucket, afraid of what lies ahead. Then, without notice, you are dumped back into the river! But now you are upstream of the dam. You have just a short way to go to get back to your spawning ground. But you are not in the clear yet. Just up ahead you sense your way. You must pass through a dark and dingy tunnel, under a large strip of concrete with huge hunks of metal barreling overhead. The culvert you are passing through is a stream crossing, where a road passes over the stream. It has been a wet spring so there is just enough flow for you to pass safely. Had it been a dry spring, this culvert would be full of sticky mud and swimming through it would be impossible.

As you can see, this culvert can pass fish.
(Photos courtesy of NRCS)
Despite the odds, you have made it to your spawning ground! Unfortunately, only a few of your kind made it this far. Your school has decreased in numbers, but you make the best of it, and hope the weather and predators will be kind to your young.
No fish could jump high enough to make it into this culvert!
Your job is done. You follow the flow of the river back out to Narragansett Bay where you meet up with the rest of your school and return to life at sea.

While dams once powered the Industrial Revolution, and culverts allow us to pass safely over streambeds, these man-made obstacles can prevent wildlife from accessing their native habitats. In Rhode Island there are more than 671 dams. While some dams hold back water for us to drink, or maintain the level of a lake or pond, others serve no purpose. In fact, 180 dams in Rhode Island are classified as hazardous to life or the environment in the event of failure. The owner of the dam is responsible for maintaining their dam, however, many of the historical dams in Rhode Island have no identified owner because the mills they once powered are long gone. Despite the difficulties of ownership and strained fiscal situations, the watershed organizations and associations continue to work toward restoring the natural flow and environmental connectivity of the rivers. In some cases this means building a fish ladder, or installing a bypass channel that will allow fish and other animals to move upstream without having to leave the river. But when possible, the dam is just removed. By removing a dam all together, we not only re-establish the connection between the river and the Bay, but we eliminate maintenance cost.
If the culvert in the red square is repaired it would
open more than 17 miles of habitat in the
Pawcatuck River watershed to fish and wildlife.

The culverts that carry the streams under our roads were not always designed with fish and wildlife in mind. There are more than 2,780 miles of river within the Narragansett Bay Watershed. This does not include the streams or brooks that may flow through your backyard or neighborhood. Nonetheless, these streams and brooks play a significant role in feeding the rivers, connecting habitats and providing food and shelter to our fish and wildlife. The Natural Resource Conservation Service (NRCS) has identified 4,353 stream crossings in Rhode Island. They have inventoried more than 950 stream crossings in 12 watersheds in Rhode Island so far.  The inventory identifies the characteristics of the crossings and assesses the quality of the crossing based on standards developed by the University of Massachusetts, Amherst Extension program in the College of Natural Sciences. Within the Wood-Pawcatuck Watershed alone, more than 150 culverts are classified as severe barriers, meaning they do not support the needs of fish and wildlife.

As part of this project, NRCS is working with landowners and other organizations to identify potential restoration projects. Landowners with culverts on their property are encouraged to apply for grants under the Wildlife Habitat and Incentives Program to fund the restoration of their ineffective culverts. To learn more about this project visit the Rivers and Streams Continuity Project at UMass Extension.
Lesley Lambert


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