It's an A-student kind of crowd at the Pennsylvania Resources Council's rain-barrel workshop. The instant instructor Nancy Martin-Silber asks how much of Earth is covered by water, one of the nearly 60 adults here shouts "Seventy!"

A third of this highly alert audience -- lots of organic gardeners here -- attended the PRC's composting classes, too. And one woman knows, and shares, the fact that corn-gluten meal is a "pre-emergent herbicide."

But although everyone's packed into Point Breeze's little Gemini Theater to learn about rain barrels, they'll have to wait. First, Martin-Silber, armed with PowerPoint, is lecturing about something even more important: watersheds.

A watershed is a land area that drains into a single body of water, and whose health governs a region's water supply for drinking, bathing, agriculture -- everything. Each stream has its own watershed; the Allegheny and Monongahela watersheds are part of the Ohio's, one of three major watersheds in the state.

Our watersheds are troubled, and not only by factory effluent. Increasingly, there's "nonpoint-source pollution," historically an agricultural problem, but more and more a function of development. When it rains in woodlands, the soil absorbs half the water, and most of the rest quickly evaporates. In paved environments, by contrast, more than half the water runs off, carrying debris and toxins into streams. Heavy runoff both prevents groundwater from recharging (the rain can't percolate down) and causes flooding.

Our area's best-known assault on its watersheds occurs during rainstorms, in older sewage systems without separate pipes for stormwater. Martin-Silber says that as little as one-tenth of an inch of rain can cause combined-sewer overflow. That's a euphemism for "raw sewage in the river" -- and, because of leaky old pipes, the sewage gets into the groundwater, too. Each year, she notes, "We have enough raw sewage entering our groundwater to fill Heinz Field about a hundred times."

"Disgusting," says a woman in the crowd.

Lawn chemicals, agricultural pesticides, automotive fluids and other household hazardous waste also trickle into streams. "What goes in your lawn ... goes in the river," says one of Martin-Silber's slides. Some toxins make male fish grow eggs.

It's a lot of information. When, after 45 minutes, Martin-Silber announces, "Finally, rain barrels," her listeners voice a mock cheer.

If your rain gutters drain into sewers, one small way to mitigate flooding, pollution and combined-sewer overflow is to divert a downspout into a rain barrel. The roof of a house with a 1,000-square-foot base sheds 24,000 gallons annually. The 55-gallon barrels PRC recommends slow the flow of stormwater into streets and sewers, and provide users free, and chlorine-free, water for lawn and garden. (However, Martin-Silber cautions that rain that runs off asphalt shingles with zinc in them shouldn't be used on vegetables.)

One attendee is a ringer: Brenda Smith, head of the Nine Mile Run Watershed Association. The group's accomplishments include installing some 700 rain barrels in the eastern communities draining into that Mon tributary. The Association charges $100 to install barrels in its watershed; the PRC's workshop fee of $30 includes a kit with all the hardware needed to harvest and access rain water -- but not the barrels themselves. Those you can get used at various establishments (including some dairies) for just a few dollars or, for a few dollars more, new or refurbished at Highland Park's Penn Barrel.

In three years of rain-barrel workshops, this mid-April class was the best-attended, says Martin-Silber. She needs only the final 10 minutes of the workshop -- and a few hand tools, a power drill and a jigsaw -- to adapt a sample blue plastic barrel for rain harvest.

"Whenever I can do a little bit to feel like I'm contributing to the overall health of the planet, I'm doing what I can," says Cindy Nelson, a workshop participant from Point Breeze. "If I can water my garden with rainwater, why not?"

 

The PRC's next Watershed Awareness/Rain Barrel Workshop is at 6:30 p.m. Thu., April 24, at Westinghouse Lodge, in Forest Hills. The season's final workshop is Thu., May 1, at Whole Foods Market, in East Liberty. 412-431-4449, x247