The primary source of drinking water for 200,000 people in Chester and Delaware counties is edging ever closer to becoming tainted, but a new $798,000 grant from the National Fish and Wildlife Foundation is about to pour in and help clean up the problem.

The grant will help the Chester Water Authority block contamination of Octoraro Creek by investing in more monitoring and farm-management best practices that reduce runoff, according to a Chesapeake Bay Journal report by Rona Kobell.

The problem is all the nitrates from fertilizer, especially manure spread atop frozen ground, that seep into or wash into the water supply. Those nitrates have caused Octoraro Creek water samples to draw near — but never exceed — safe-drinking-water standards.

“If you can get enough of the agricultural community to do the (best management practices), then yes, we could expect to see decreases (in nitrate),” said Sharon Fillmann, Chester Water Authority Chief of Treatment and Pumping. “But it could take 10 to 35 years to see changes to the groundwater in the reservoir.”

When nitrate contamination is at its worst, water from the Susquehanna River is pumped into the Octoraro Creek supply to dilute it.

Read more about the efforts to clean up Octoraro Creek in the Chesapeake Bay Journal here.