Wider stream buffers are better for water quality

In 2013, Frederick city drinking water violated federal and state health standards for byproducts of water disinfection. The root cause: high levels of runoff — soil and other organic matter — in Lake Linganore, which provides 42 percent of the city’s water, the Monocacy River and other smaller sources.

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When drinking water reservoirs are not well-protected, the water we drink becomes loaded with silt and other pollutants. Then, when it is treated to control bacteria and other bugs, the chlorine and similar compounds (ammonia, basically) used to kill the bugs react with the organic matter in the water to form new contaminants, known by regulators as disinfection byproducts.

DBPs, unfortunately, present their own risks. They have caused birth defects, cancer and other problems in animal studies. It’s a bad trade-off: acute illness on the one hand, long-term problems on the other. Health authorities set standards to limit human exposure to these toxic byproducts, but these health standards do not represent a truly safe level and instead represent a balance between controlling bacteria and acute illness with the longer-term consequences of the toxic byproducts.

There is little the city of Frederick can do to lower DBP levels using the current treatment regimen when the source water delivered to the city for purification is polluted with sediments, manure and
decomposed organic matter.

The best way to keep DBP levels low is to protect the water at its source. Clean water in the reservoir means clean water at the tap.

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This is exactly what Frederick County is not doing by approving development on 67 percent of the land around Lake Linganore. If this development moves forward, more than 1,514 acres of open space will become roads, rooftops, driveways and otherwise altered landscapes, and the Linganore waterways will be increasingly polluted with soil, organic matter, street runoff and chemicals. There will be more flash flooding that further damages stream banks and streambeds.

The best way to protect streams and the Lake Linganore reservoir from pollution is to keep buffers of vegetation around the waters. For many years, Frederick County officials have debated the width of vegetation necessary to adequately protect the streams. The title of a 2007 article covering the American Society of Agronomy’s research findings is telling: “Wider Buffers Are Better.”

In 2006, Frederick County developed an action plan for the Linganore Source Water Protection Plan. Back then, construction was allowed up to 50 feet from the lake. Since water (and the sediment that it picks up) flow faster on a steeper slope, any land disturbance on steep slopes has a greater negative impact on water quality. The plan explicitly says that “the greater the minimum stream buffer width, the greater the margin of safety in terms of water quality protection.”

In 2007, under Jan Gardner’s leadership, the stream buffer regulation was amended to “regulate it to slope/grade of the adjacent stream valley corridor.” By increasing the buffer zone on steep slopes, water quality was better protected. The regulation also required greater protection for 100-year and historic flood plains, perennial and intermittent streams and their buffers, wetlands and their buffers, steep slopes and forest cover.

Blaine Young’s administration slashed those protections in 2013, setting back Frederick County’s efforts to protect the lake’s water quality.

Thanks to Frederick County Councilman Jerry Donald, our County Council will begin a public discussion about what building is allowable in a buffer zone. It would be prudent for the council to also discuss streamside vegetation buffer width to protect drinking water and minimize health risks to the city’s residents.

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A report on Frederick city drinking water and human health impacts can be found at http://friendsoffrederickcounty.org/?p=6178.

This column was originally published in the Frederick News Post.