Hundreds of dead fish were spotted Friday evening floating down the Codorus Creek.

Patrons dining at the Waterway Bar and Grill, 220 W. Philadelphia St., contacted Michael Helfrich, Lower Susquehanna Riverkeeper, who said approximately 300 dead fish were noticed floating by at 7:40 on Friday night.

Helfrich went to the bridge at College Avenue first, where he saw several dead fish floating by.

"Then I went down to the Waterway to check to make sure there were more, and I saw about five to 10 floating by every minute," Helfrich said. "So it was definitely a good many."

Testing: An agent from the Pennsylvania Department of Environmental Protection arrived at 8:15 p.m. to search the area, and estimated between 50 to 100 fish were floating in the creek at that time, said Lisa Kasianowitz, spokesperson for the DEP.

Shad and sucker were the only two species of fish found floating, which is a good indication it was caused by single event, said Kasianowitz.

Otherwise the other types of fish in the waterway would have shown signs of distress, but they did not, she said.

The DEP has not determined the cause yet, Kasianowitz said.

The emergency responder conducted a dissolved oxygen test and a pH test to check the balance of the water, and both tests turned out fine. Water samples sent to the lab can take up to one week to be processed, said Kasianowitz.

If the test results reveal a chemical that could have leaked from a local company, the DEP will contact the companies that might have been responsible for the incident.

"We take polluting of Pennsylvania waterways very seriously and we always want to at least try to single out the source," Kasianowitz said.

"The creek has really bounced back tremendously in the last 10 years or so," Helfrich said. "We have many different species of fish here in the city, and lots of people take advantage of that, so it is more of a concern now that the creek is healthier."

The creek is not stocked, but everyone is welcome to fish there.

- Reach Chelsea Shank at 505-5432 or cshank@yorkdispatch.com.