Response of a linked lake-stream system to dam removal and restoration of migratory fish.

PI: Kevin Simon, University of Maine

The National Need

The installation of dams has caused environmental damage by changing the physical nature of rivers and by blocking the movement of migratory fish that move between the ocean and rivers. The recognition of these problems, and the increasing costs of maintaining aging structures, has made dam removal an increasingly popular way of restoring ecosystem health. In Maine for example, plans for the removal of 2 dams and the bypass of a third on the Penobscot River are currently proceeding at an estimated cost of more than $50 million with the primary goal of restoring access of migratory fish to inland waters, aiding the recovery of Atlantic salmon. However, few river restoration projects such as dam removals are ever monitored for success. Such monitoring is needed to direct future restoration efforts to ensure successful restoration of freshwater systems

Program Overview & Objectives

This research will use a dam removal project on a small tributary to the Penobscot River in Maine as a pilot study to examine how lakes and streams respond to dam removal and subsequent restoration of migratory fish access. Dam removal is expected to allow migratory fish to enter the lake-stream system above the dam where they will interact in lake and stream food webs as both predators of smaller animals and as prey for other animals. In addition, these fish may transport nutrients inland, stimulating the productivity of the lakes and streams that they reside in. The dam removal may have detrimental effects by releasing sediments accumulated below the dam and we plan to monitor the influence of these sediments on the downstream organisms. This project will serve as a pilot study to help direct future dam removal projects.

Project Plan

We will use both pre- and post-dam removal sampling at key locations in the streams and lakes above and below the dam that will be removed. In particular we will measure key biological (algae, invertebrates, fish) and physical (water chemistry and habitat structure) indicators of ecosystem health before and after dam removal in both reference and impacted sites. In addition, we will determine the extent of delivery of nutrients and energy to a lake-stream system by migratory fish in a restored watershed. This information will be linked to other studies focusing on the fish communities and physical habitat of the restored system to develop a comprehensive picture of how dam removals may influence the aquatic systems upstream of dams.

 

Contact Information:

Kevin Simon
School of Biology and Ecology
University of Maine
Orono , ME 04469 -5722

207-581-2618