A True Fish Story

By David Winer

Sycamore Islander, May 2000



Cofferdam and crane about a mile below
Sycamore Island near the Virginia shore.
There is a new fish passageway at the Little Falls Dam. This structure allows the long-denied shad and other species access to prime spawning and feeding spots upstream. The dam now allows migratory and resident fish access to ten miles of historical spawning grounds upstream of the dam, as far as Great Falls. In the original construction, the dam did include a vertical slot fishway for migrating fish, but it was later abandoned because of poor location and high maintenance caused by large amounts of debris that it trapped.

The new fishway is in part a result of Maryland's fish passage program that stemmed from the 1987 Chesapeake Bay Agreement to restore the health of the bay. The program seeks to restore migratory fish species to or close to historic levels. The program began in 1988 and since then 292 miles of rivers in Maryland have reopened to fish. However, shad populations are still in bad shape. In a recent ranking of the health of bay fish by the Chesapeake Bay Foundation, shad received a ranking of 3 out of 100. Experts said that the new fishway will make a huge difference in future ranking of the shad. The fishway at the Little Falls Dam is the latest in a series of dams in the Potomac basin modified to assist fish migration. Other nearby sites include: Mattawoman Creek, Hancock Run, Rock Creek, and the Northeast and Northwest branches of the Anacostia River.

From inside the cofferdam, views of the Little Falls pumping Station, and below the dam,
the beginning of the mile-long section of Little Falls.
At one time, shad was the most important commercial species in the Chesapeake Bay. The decline of shad and other fish in the region began in the 1930s and continues to today. Declining water quality, construction of dams, loss of habitat, and overfishing have slowly caused the decline of the shad. These factors lead to a 1982 moratorium on fishing in Maryland. Virginia implemented a similar ban in 1993.

In 1995, the Interstate Commission on the Potomac River Basin (ICPRB) began working with the U.S. Fish and Wildlife Service and citizen volunteers on a project to restock shad to the Potomac. The project is lead by Jim Cummins, an aquatic biologist with ICPRB. Each spring during shad spawning season, he and volunteer assistants catch shad on the Potomac near Mount Vernon. The fish are squeezed of their eggs and milt. The fertilized eggs are taken to the U.S. Fish & Wildlife Service's National Fish Hatchery in Charles City, Virginia. After hatching, the shad fry are tagged for future identification with a chemical substance (oxytetracycline). This leaves a fluorescent trace that will be detectable in certain tiny bones in the heads of the fish, even as adults.

Workmen observing the proceedings. Digging from the river bottom in the fishway notch.
These fry are released in the ten-mile stretch of river upstream of the Little Falls Dam. The fry should naturally imprint their release site in this same part of the Potomac, and should return as adults to spawn. Since 1995, over seven million shad fry have been raised and released into the Potomac above Little Falls Dam.

This spring, Jim Cummins and his volunteers are again out on the river in the stocking effort and to see if any of the shad broods have returned to spawn. Experts are confident that the fishway will assist in the restoration of the shad population and other migratory species including river herring, striped bass, white perch, and resident species such as smallmouth and largemouth bass, bluegill and other sunfish, and walleye.

Inside the cofferdam. Debris from the dam-cut is scraped
up by a backhoe into buckets for removal. Water leaking
into the cofferdam is pumped out through the hose on
the right. River level is about ten feet above the buckets
Buckets of old dam material are transferred to barges.
The fishway is an innovative design that incorporates three W-shaped labyrinth weirs within and below a 36-foot wide, 4-foot deep notch in the dam. The design and modeling for the fishway was performed by Dr. Mufeed Odeh and a team at the U.S. Geological Survey/Biological Resources Division of the Conte Anadromous Fish Research Center in Turners Falls, Massachusetts in 1994 and 1995. The weirs reduce water velocity to levels that allow fish to move upstream over the passage despite a wide range of river flow. The structure is 75 feet from the Virginia shore, where migratory fish will be attracted below the dam. Cost of the $2-million project was shared between the U.S. Army Corps of Engineers and the Maryland Department of Natural Resources.

Construction of the notch was completed just in time for this spring's mighty spawning runs.


-- Re-written by David Winer from official materials and from interviews. Thanks to the following who provided information and photos for this piece: Curtis Dalpra and Jim Cummins, Interstate Commission on the Potomac River Basin; Mike Bailey, "a friend of the shad"; and Ray Fletcher of Fletcher's Boats.