Pa. monitors Ridley Park Lake after 1,000 fish die

A Pennsylvania state biologist is monitoring oxygen levels in Ridley Park Lake, where 1,000 fish died during the weekend, a state Department of Environmental Protection official said Wednesday.

The biologist is testing twice a day to measure any fluctuations in the oxygen in the water. Deoxygenation caused the fish to surface and die starting Saturday, but the reason isn't clear.

"It's not that unusual when we have extreme heat and cloudy days for the oxygen level to drop at night and rise during the day, but you have to be there when it happens. You can't tell what happened 24 hours before the fish were found," DEP spokeswoman Deborah Fries said.

Ridley Park Borough officials said hot weather plus runoff from construction or road surfacing were being considered as possible reasons for the drop in oxygen. Water from the small, man-made lake was being analyzed in a laboratory, Fries said. Officials hoped to have some results next week.    - Bonnie L. Cook