On October 6th, 2005, the Maryland DNR Fish Passage Program, the U.S. Fish & Wildlife Service and other partners (see list below) began the demolition of the Octoraro Creek Dam near Rising Sun, Maryland. The dam which had been a barrier to herring and shad for over 100 years was completely removed less then a week later, opening 19 miles of historic habitat and restoring the stream to a free-flowing condition. This project is an important milestone for the Maryland Fish Passage Program and marks the first time that a permit was granted by MDE to allow in-stream work in a free-flowing stream. Typically a temporary coffer dam would be constructed to dewater the site so that equipment would not be in the stream water. This is done to reduce the amount of sediment washed downstream during the removal. However, installing coffer dams greatly increases the cost and length of time to complete a project. After several detailed studies of the stream and the dam, it was determined by DNR and MDE that this removal would not need a coffer dam since there would be very little impact from sediment. The dam was removed by driving a track-hoe on the face of the dam and removing rocks one-by-one. On October 6th, a small section was removed from the center of the dam to let the pond area behind the dam drain to a predetermined level. After several days to allow stabilization, work continued to remove the remaining sides. As the rocks were removed, they were placed along the bank to fill in sections that had been eroded away and to stabilize the stream bank. On November 3rd, volunteers from DNR, FWS, and the Octoraro Watershed Association completed the stream restoration by planting over 100 trees and shrubs along the rivers edge. These plants will help shade the stream and stabilize the newly exposed stream banks.
Before & After Dam Removal
This project showcases collaboration among multiple agencies. Project Partners include: Maryland Department of Natural Resources - Fish Passage Program, U.S. Fish & Wildlife - Chesapeake Bay Field Office, National Oceanic & Atmospheric Association, American Rivers, Environmental Protection Agency, The Chesapeake Bay Program, Chester Water Authority, Octoraro Watershed Association, The Port Gun Club, Chesapeake Bay Foundation, Maryland Department of the Environment, and the Army Corps of Engineers.
Although the dam was primarily removed to promote fish passage, dam removal will also provide portage-free canoeing from Pennsylvania to the Susquehanna River. In general, dam removals create a number of positive environmental and cultural changes: best passage opportunities for migrating fish; a reconnection of aquatic communities (mussels, crayfish, etc.); reduced thermal pollution; increased dissolved oxygen; improved riverine fish habitat; improved macroinvertebrate habitat; portage-free paddling; reduced safety concerns; and, free-flowing natural river conditions.
For more information on fish passage and dam removals, please follow these links:
Featured Article (This article describes the fish passage program)
U.S. Fish & Wildlife Link
Chesapeake Bay Program Link