{"id":42711,"date":"2024-10-04T08:00:47","date_gmt":"2024-10-04T12:00:47","guid":{"rendered":"https:\/\/news.maryland.gov\/dnr\/?p=42711"},"modified":"2026-04-21T11:18:20","modified_gmt":"2026-04-21T15:18:20","slug":"one-last-hurdle-american-eels-navigate-over-ellicott-citys-daniels-dam-with-a-new-ladder","status":"publish","type":"post","link":"https:\/\/news.maryland.gov\/dnr\/2024\/10\/04\/one-last-hurdle-american-eels-navigate-over-ellicott-citys-daniels-dam-with-a-new-ladder\/","title":{"rendered":"One Last Hurdle: American Eels Navigate over Ellicott City\u2019s Daniels Dam with a New Ladder"},"content":{"rendered":"

Recent dam removals on the Patapsco River ease their path<\/i><\/p>\n

\"Eels<\/a>

American eels get a little help from some Maryland Conservation Corps members to complete their epic migration from the Sargasso Sea. Photo by Joe Zimmermann<\/p><\/div>\n

A thousand or so miles into their migration, some American eels find themselves in the bottom of a bucket.<\/span><\/p>\n

One late summer day, a Maryland Conservation Corps crew took a net to the holding tank at the top of Daniels Dam on the border of Baltimore and Howard counties. Earlier this season, they had built a new eel ladder here, replacing an older structure, and throughout the migration they continue monitoring it for new eels. By the time they reach the dam, the eels are a few inches long, thinner than a pencil, and eager to get upriver.<\/span><\/p>\n

After counting and weighing the squirming mass\u201413 eels at a combined 18 grams\u2014the team releases them off the upper side of the dam, where they can continue their journey for miles ahead, unimpeded by man-made obstruction.<\/span><\/p>\n

\u201cI\u2019ve kind of come to love them,\u201d Jett Clarke, an MCC member who worked at Patapsco State Park over the summer, said of the eels as they slithered away among the rocks in the riverbed. \u201cWe got to build this project, and now we see the effect it has.\u201d<\/span><\/p>\n

Four hundred and fifty feet of stone masonry that cuts straight across the waterway, Daniels Dam has slowed the passage of the Patapsco River a few miles from Ellicott City since the 1830s, when it powered mills for producing canvas and denim. This year, the nonprofit American Rivers began a feasibility study for the possible removal of the dam, which is now long out of use. The Department of Natural Resources, which owns and manages the dam, supported American Rivers\u2019 application to fund the study.\u00a0<\/span><\/p>\n

In the meantime, the slippery, snakelike fish keep coming.<\/span><\/p>\n

The eel is a strange and complex creature. They\u2019re an often-caught, slimy inconvenience for many anglers. But American eels are a critical part of the freshwater ecosystem, a vital piece of the food web and a transportation system for freshwater mussels. Globally, several eel species are in decline or imperiled, in part because of dams that sever large areas of habitat. And because of their epic migration and mysterious life cycle, eels have also beguiled scientists and the public for hundreds of years.<\/span><\/p>\n

One of five eel ladders in Maryland, the Daniels Dam ladder offers a chance for eels to access a vast stretch of otherwise largely inaccessible upriver habitat. But with its simple setup, the ladder could also be a model for easy eel passage with a low price tag.<\/span><\/p>\n

A DIY solution<\/b><\/p>\n

There\u2019s been an eel ladder at Daniels Dam since 2014, allowing tens of thousands of eels to pass over the structure. But with the original ladder in disrepair\u2014and the possibility that the dam won\u2019t be here too much longer\u2014Jim Thompson, a biologist and the fish passage coordinator for the Maryland Department of Natural Resources, saw an opportunity.<\/span><\/p>\n

He and DNR biologist William Harbold wanted to see if a \u201cmore homemade design\u201d could be effective. The new eel ladder cost less than $600 and is made from equipment bought at a hardware store, Thompson said. The team of MCC members put it in place in less than a day.<\/span><\/p>\n

\u201cIf we can pass 30,000 eels in the next five years, it\u2019s well worth the cost,\u201d Thompson said. \u201cEspecially for the low cost of 600 bucks.\u201d<\/span><\/p>\n

\"The<\/a>

The new eel ladder (at left) is a modest PVC pipe that spans about 43 feet up the edge of Daniels Dam. It has a few openings on the top along its length for upkeep. Photo by Joe Zimmermann<\/p><\/div>\n

The previous ladder had already operated beyond its intended lifetime, Thompson said. Larger and made of steel cable trays, the former model also required more maintenance.<\/span><\/p>\n

If this ladder proves successful, Thompson said it could be a model for other ladders that could be put in place at low cost and still provide substantial benefits to eels.<\/span><\/p>\n

Eel ladders are like fish ladders, which are structures that allow fish like salmon, shad and herring to cross obstructions in the water. Because of eel biology, namely their size and climbing ability, their ladders are often less involved, allowing for more DIY solutions. American eels are powerful climbers, and some can even scale the bare face of the 27-foot-high dam, though the ladder allows for many more crossings.<\/span><\/p>\n

Named for its function rather than its form, the eel ladder at Daniels doesn\u2019t resemble a step ladder. It\u2019s more of a simple tube\u2014or a kind of eely waterslide\u2014that stretches from the top of the dam to the water below, where it runs a few feet under the surface and provides an attraction flow that interests eels. The bottom of the pipe is covered with substrate netting that gives the eels enough purchase for their ascent.<\/span><\/p>\n

There had been a fish ladder on the Daniels Dam as well, but it was closed after the invasive species Chesapeake Channa, or northern snakehead, were documented below the dam, Thompson said. Now, however, Channa are present both upstream and downstream, which has influenced the discussion around removing Daniels Dam.<\/span><\/p>\n