Rock Creek Fish Ladder

Man-made obstacles in Rock Creek blocked migrating fish from reaching their ancestral spawning grounds for over a century. Clever solutions now make it possible for herring and shad to finally come back home.


Presented by NatureServe and the National Park Service

Featuring Bill Yeaman, Natural Resource Specialist, Division of Resource Management, Rock Creek Park, NPS

Author, Narrator, and Illustrator:  Erin Ziegler, Explore Natural Communities Intern Summer 2015, NatureServe

Videographer and Editor: Grace Novak, Explore Natural Communities Intern Summer 2015, NatureServe

Produced by: National Park Service

Music: Swimmey Texture, and Montauk Point, by Kevin MacLeod (
Licensed under Creative Commons: By Attribution 3.0


  • Rock Creek Park
  • National Capital Regional Office
  • National Capital Region Network – underwater video footage
  • Urban Ecology Research Learning Alliance
  • Explore Natural Communities Internship Program


Video time:  2:52 minutes

Voice 1:

Out in the Atlantic Ocean, fish like river herring make their home in the open waters. They compete with other species, dodge predators, and swim free in the salt water. Though the ocean is a prime habitat for fish growth, it may not be the best place for a little herring to hatch. Anadromous fish, like river herring, are a special type of fish that live in the ocean, but lay their eggs in fresh water.

So those herring that reach maturity head back to a fresh water river to lay their eggs. In the spring they swim up the Chesapeake Bay and into the fresh water rivers like those where they were born—each striving to contribute to the next generation of herring. Some swim north through the Potomac River and eventually find their way up to Rock Creek Park. But here, they hit a wall. In 1903, a decorative waterfall was built on Rock Creek four miles from the Potomac River at Peirce Mill, creating a beautiful water feature for the historic mill, but a big problem for the migrating fish.

Obstacles like this one once blocked the fish passage, making it impossible for fish to get to the safe waters upstream to lay their eggs. Luckily everything changed when in 2006 Rock Creek Park reopened 21 miles of the creek to the fish whose ancestors were born here. But the waterfall at Peirce Mill still blocks the creek—so how are fish getting around it? They climb a ladder of course!

Bill Yeaman:

A fish ladder is a structure that is built and designed to permit the movement of fish above a barrier of some kind and it could be a sewer line or, in the case of Rock Creek, it’s a historic dam that’s eight feet tall. There’s a baffle that will increase in height as you go from the bottom of the fish ladder to the top. The fish ladder is built so that fish can move past the dam, up the series of baffles to continue upstream.

Voice 1:

Now that the fish can come home to lay their eggs, a new generation of river herring and shad are able to hatch in the safety of Rock Creek before they swim back downstream to the ocean. Maybe one day, if they’re lucky, they’ll find their way back to Rock Creek again.

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Fish ladder on dam - Tom Paradis