About 1,400 trout were killed by flooding at Allentown's Lil-Le-Hi Trout Nursery early Monday evening.
The fish kill was caused by flooding generated by Monday's storm, said city spokesman Mike Moore.
"We were flooded and we don't honestly know how all these fish died," said Reggie Rickard, a volunteer at the hatchery. "We've been flooded previously when we got hurricanes and things like that and we had a lot more fish in at that time and we didn't have near the kill that we had this time."
Moore said 5,000 trout remain in the nursery. He added it's too soon to predict what the impact will be on trout stocking, if any.
The nursery, a popular city attraction, is along Fish Hatchery Road in the Lehigh Parkway.
Most people simply call it the fish hatchery, although it hasn't been a hatchery since the early 20th century.
Every year, the Pennsylvania Fish and Boat Commission delivers thousands of trout to the nursery from state hatcheries. They stay at least two years in the nursery's spring-fed pools and raceway, then are stocked in streams.
Rickard, also a member of the Pioneer Fish and Game Club, one of three gun clubs that co-ops the hatchery with the city and the PA Fish and Boat Commission, says this amount of dead fish will pose problems when it comes time to stock this spring.
"Big decrease in the stocking program, that's what it means," Rickard said.
The hatchery stocks the Little Lehigh, Jordan Creek, Cedar Creek and Union Terrace Pond, according to Rickard, in April or May every year.
"Not good, we spend a lot of time and money on it and it was just thrown out the window," Rickard went on.
Fish have been raised there since 1883.
The nursery site is susceptible to flooding because a steep hill is directly behind it.
Moore didn't have specifics but said there was a similar incident at the nursery five or six years ago.