Some water companies around the state have begun warning customers that chemicals they use on their lawns could lead to stormwater pollution, thanks to heavy rains in the past few weeks.

A notice from Indiana American Water says the wet spring means customers should be careful about using fertilizers, herbicides and pesticides only in the prescribed manner when trying to, as the company puts it, “get the perfect yard this year.”

David Scott, the pesticide administrator at the Office of the Indiana State Chemist, says many water companies test their water often following a downpour…

“A lot of the water suppliers are experienced enough they almost can tell you based on the amount of rainfall and the amount of research that’s been done, they know when they’re going to have to up their treatment capabilities.”

Scott says it’s an ongoing debate whether agricultural land – which uses lots of chemicals but doesn’t often drain to municipal sewer systems – or urban lawns are a bigger contributor to toxic runoff.

He says what is clear is that the runoff problem is worse in Southern Indiana, because the state’s river basins drain toward the Gulf of Mexico.

The federal Environmental Protection Agency, which monitors chemical runoff and other water pollution, has forced several Indiana cities — including Terre Haute and West Lafayette — to begin combined sewer overflow projects aimed at reducing discharges of untreated stormwater into local water sources.

Those spills happen most often during and after heavy rains.