Improving on storm water ponds RunoffNew rules designed to protect the state's 17,000 miles of streams could work, but only if they are enforced.

On The Bay

August 14, 1998|By Tom Horton | Tom Horton,SUN STAFF

HAVE WE hardened our hearts to the future of the state's estimated 17,000 miles of streams?

Certainly we have hardened a lot of the lands that shed rainfall to these tributaries where the bay begins.

And the bottom line, despite 15 years of storm water management laws that say, "We care," is that we've degraded probably hundreds of miles of streams.

To understand why this sad state of affairs now has a chance -- but certainly no guarantee -- of improving, you need to understand a bit about rain.

Early settlers of the bay region, for example, thought rain was rain; but English rain was soft and sea-spawned and misting, nothing like the gully-washing downpours of our continental weather.

The agricultural plowing practices they established here, which worked all right in their gentle soaks, set us up for generations of topsoil loss, erosion and streams smothered in silt.

In the modern landscape, the key to rain is how it gets translated from sky to stream by the urban and suburban lands on which it falls.

Where these lands are still clad naturally, as with forests, the rain's force is diffused and scattered by the canopy, trapped and filtered through leaf litter and absorbed into the ground.

Maybe 1 percent or less trickles overland into streams. The rest seeps out of the ground water, clear and cool and clean, over weeks and months, nourishing the stream through its bed and banks.

But where rainfall lands on rooftops, driveways, streets and parking lots, it begins moving rapidly in solid sheets. Focused further by curbs and gutters and drains, its force intensifies sharply, like sunlight through a lens, cannonballing downstream with destructive velocity.

It also scours a brew of pollutants from the pavement -- sediment, dog and cat feces, toxic deposits from automobiles.

Then, quickly, it is gone downstream, leaving very little to soak in, to replenish the stream during drier times.

To make the rain falling on suburbia act more like it fell on forest, Maryland in 1983 adopted what was touted as one of the nation's foremost storm water management laws.

Its goal was to equalize the pre- and post-development "hydrograph"; i.e., to make the quality and quantity and velocity of water leaving a new garden apartment complex in Towson mimic the flows of rain from the open space it had supplanted.

What actually happened was that county and state government let developers off with merely building thousands upon thousands of those "storm water" ponds you see everywhere PTC from highway interchanges to schoolyards.

Such ponds aren't all bad. They afford some flood control, detaining runoff until a storm passes. Some become nice pocket wetlands.

But study after study is showing they don't come close to maintaining water quality, or natural water temperatures, aquatic life, or anything like the pre-development "hydrograph."

Ponds also need frequent inspections -- as often as monthly -- and expensive maintenance (like dredging) and repairs to function even minimally.

Prince George's County spends some $2 million a year on this, while Montgomery County has tried to pass it off to homeowners associations, which are ill-equipped to do it. Other counties, like fast-growing St. Mary's, inspect their ponds only every few years.

Now the Maryland Department of the Environment, the ultimate authority over storm water management, has issued a draft of new standards and guidelines, the first overhaul since 1983.

It is "real good, maybe the best in the country," says Richard D. Klein, whose Community and Environmental Defense Associates consults with citizens' groups fighting bad development.

Klein, who lives in northern Baltimore County and watched White Marsh Mall destroy his boyhood stream, should know.

He and James Gracie, now a stream restoration consultant, were the activists who pushed Maryland's storm water legislation into law, over developers' frenzied opposition.

Klein warned as early as 1979 that ponds alone would be a bad approach. He was one of the first to find that streams and wetlands degraded at surprisingly low levels of development.

Even 2-acre homesites throughout a stream basin altered runoff patterns enough to disenfranchise sensitive stream dwellers like mayflies and stoneflies, he found. Newer research shows degradation can begin with density as low as one house per 6 acres.

MDE's new manual -- still a year or more from being implemented -- goes a long way, Klein says, toward getting away from the ponds approach. It focuses on water quality, on letting more rain soak into the ground; it also offers incentives for solutions like maintaining open space, creating wooded and wetland stream buffer zones and replacing curbs and gutters with grassy swales to diffuse runoff.

But he fears that without aggressive enforcement, the new approach still has enough loopholes "to lock us into another 10 or 20 years of mostly ponds."

Maryland, he points out, is projected to increase its developed landscape from around 11 percent of the state to 22 percent in the next couple of decades; "and I think a lot of that is liable to happen in the next five or 10 years."

On paper, he says, it is possible to come "pretty close" to the goal of no change in stream quality after land development, "but in reality, no one really knows."

"Until we start realizing our technology is not foolproof and start setting some limits on how much development we can ultimately allow, we're liable to see a lot more degraded miles of streams," he says.

Pub Date: 8/14/98

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