Baltimore Reservoirs’ Public Enemy No. 1—the Zebra Mussel

by Laurel Peltier, Greenlaurel, Church of the Redeemer

A pesky alien shellfish that wreaks havoc on waterways is getting closer and closer to Baltimore’s drinking water reservoirs. Zebra mussels, stowaways from Russia, were found last spring in Hyde’s Quarry in Westminster, Maryland.

“Baltimore’s Department of Public Works has been ever-vigilant about keeping these invaders out, but this was way too close for comfort,” said Clark Howells, Watershed Section manager for Baltimore DPW.

DPW moves about 280 million gallons of water each day from Loch Raven, Prettyboy and Liberty reservoirs through huge pipes to drinking water filtration plants.

The mussels are therefore a “significant threat” to the reservoirs, Howells said, “because once introduced, it’s nearly impossible to get rid of them. Zebra mussels are prolific and reproduce rapidly and they have the potential to clog the water intake pipes.”

Since first being discovered in 1986 in Lake Saint Clare, located between Michigan and Ontario, Zebra mussels have taken over the Great Lakes, crushing their food web and creating vast “aquatic deserts.”

Once introduced, eradicating the alien creatures can be costly. Just last month, Carroll County approved $350,000 to kill the mussels in the afflicted quarry.

And eradication may not even be effective in our reservoirs, officials say.

While Hyde’s Quarry “is isolated and lends itself to eradication,” Howells said, “our reservoirs are different because we have billions of gallons of water, making it significantly more difficult to eradicate.”

DPW has been proactively working to keep its reservoirs Zebra mussel-free since the late ’80s, investing millions in on-site Zebra mussel eradication systems and creating a strict boat and kayak permitting and education process. As part of that process, sailboats, inflatables and gas-powered and pontoon boats are a no-go in Liberty, Prettyboy and Loch Raven reservoirs.

All legally permitted boats and kayaks enjoying the Prettyboy and Liberty Reservoirs must have this permit prominently displayed. Watch out if a boat with this sticker is caught outside of Baltimore’s three reservoirs!
During the permitting process, boat and kayak owners learn the extensive list of do’s and don’t’s, which includes a key section about Zebra mussels. Boat owners sign affidavits affirming that their boat or kayak will only be used in the Liberty, Prettyboy or Loch Raven reservoirs, a policy meant to eliminate any chance that boats will pick up the Zebra mussels in other waterways.

David Hohman, a boater from Dallastown, Pennsylvania, attests that DNR is vigilant about checking those permits.

“I was boating in Liberty a few years back, and while DNR was checking our boats for permits, we watched another guy try to back his motor boat into the reservoir,” he recollected. That boater made a faux pas by trying to adjust his vessel on top of a trailer.

“DNR was on him so fast,” Hohman said. And as it turned out, “his boat wasn’t permitted.”

Clark Howells, right. This nondescript building at Loch Raven Reservoir dam is an on-site Zebra mussel defense system in case the invaders are discovered. DPW has invested over $3 million to have these “insurance policies” at all three reservoirs.
Baltimore’s reservoirs date back to the 1920s, when city engineers designed a regional reservoir and water treatment plant system. With population growth in mind, Baltimore bought the then-rural land to build out the Liberty, Prettyboy and Loch Raven reservoirs and filtration plants. They’re situated across 25,000 acres of mostly undeveloped and forested land.

Managed by DPW, the reservoir system provides drinking water to nearly two million households in five surrounding counties–a system worth protecting from alien invaders.

“Baltimore’s reservoir system is a true regional asset,” said Howells. “It’s our only source of drinking water for millions of people.”


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