Planned Development Prompts Fears of Chesapeake Congestion

Geese take flight near the Blackwater National Wildlife Refuge, downriver from the site of a proposed development that could nearly double the population of Cambridge. (Photos By Ricky Carioti -- The Washington Post)

"Now, how do you know that you've got too much growth?"

The Blackwater Resort community would go up a couple of miles from the Blackwater National Wildlife Refuge, a 70-year-old tidal marshland whose 27,000 acres shelter the bald eagle, peregrine falcon and other threatened species. Flooding and farm runoff already create problems for the preserve, which empties into the bay.

But houses present a host of different problems. More people drive more cars, and new studies show that even relatively small flows of polluted pavement runoff can disturb waterways, especially such small rivers as the Little Blackwater. But without more study, it is hard to say precisely what impact the Blackwater development would have.

The ability of a place to accommodate people and nature is called carrying capacity, and it can be a slippery concept. In the bay region, carrying capacity "is how much pollution a population can stand," said Epstein, the bay foundation growth expert.

For a waterman, too few crabs might equal too many people. To a slow-growth advocate, one new subdivision tips the scale. To some builders, as long as there are home buyers and open land, there's room to spare.

In his cubicle in a waterfront Annapolis office, Peter Claggett searches for scientific ways to gauge the effect of people on the bay. He is a U.S. Geological Survey geographer, funded by the Chesapeake Bay Program, which is led by Maryland, Pennsylvania, Virginia, the District and a dozen federal bodies.

Better technology -- sewage treatment, runoff management and wildlife restoration -- can postpone the day when the watershed won't withstand any more people, maybe indefinitely, Claggett said.

His computer showed multicolored maps of Dorchester, with population and housing, types of soil and trees, cropland, wildlife habitat and building hot spots.

But can he calculate how many people should live there?

He sighed.

"There's no estimate of capacity that we can foresee," he said. "I'm not sure it's possible to determine an absolute limit."

What he hopes to do, he said, is help local decision makers, such as Rippons, choose more precisely where to build and where to preserve land.