Testing the Waters
The water at public beaches can draw hordes
of swimmers and a lot of bacteria, too.
Signs that say "No Swimming" are popping up more than
ever at public beaches. The water isn't necessarily more
polluted these days. But it is getting tested more often,
and people are finding more signs of contamination than
The problem is most often bacteria, and apparently they're
coming from human and animal waste. But exactly how those
bacteria get into the water is often a mystery. A recent
report from the U.S. Environmental Protection Agency says
that in half of the beach closings and advisories issued
during 2001, the sources of bacteria were unknown.
Sandra McLellan is an environmental toxicologist at
the University of Wisconsin in Milwaukee. She's helping
develop techniques that use DNA to find the origins of
this beachfront bacteria. McLellan says rain storms or
melting snow can carry bacteria from parking lots, streets
and rooftops into storm sewers and ultimately into rivers
"If you look at the amounts of bacteria that
are carried in storm water runoff, they can be significantly
high in a very large area. Almost every community has
some kind of storm water system that puts the storm water
into the rivers and subsequently the lake."
McLellan says sometimes the problems are right next
to the beach.
"Local sources, such as waterfowl roosting
or storm water runoff from pavement, can really impact
that small amount of water we're testing. It doesn't take
much to drive up those numbers, you know, those numbers
of bacteria in that water that's right next to the shoreline."
McLellan says we're likely to hear more about water
quality and swimming safety in coming years. Federal law
now requires states to develop comprehensive monitoring
plans for their beaches.