The Delaware Riverkeeper Network, a watershed protection group, has informed a Lehigh Valley cement plant that it intends to file a lawsuit if fish kills on an adjacent creek aren’t addressed.

Last month, The Inquirer reported on numerous sinkholes that have been draining Bushkill Creek and other area streams and the contention by Trout Unlimited, a nonprofit advocate for clean waterways and fisheries, that the nearby Hercules Cement plant is exacerbating the problem.

The plant’s deep quarry requires constant pumping, and on recent occasions when those pumps stopped working, Bushkill Creek ran dry. Portions of the Northampton County stream are considered “Class A” trout waters by the Pennsylvania Fish and Boat Commission.

“There’s always a reason why it happens,” Joe Baylog, president of the Forks of the Delaware Chapter of Trout Unlimited, said last month. “We just want them to come up with a solution so that it stops happening.”

On Friday, the Delaware Riverkeeper Network sent a letter to Hercules and Buzzi Unicem, the Italian company that owns the plant, demanding action and giving notice of a potential lawsuit. The DRN alleges that Hercules is in violation of Pennsylvania’s Noncoal Surface Mining Conservation and Reclamation Act, which protects and improves lands and waterways impacted by the surface mining of noncoal minerals.

The creek, according to the DRN, has been affected by approximately 15 pump failures at the plant since 1999.

“As a result of your mining activity and the dewatering of your quarry, you have caused or substantially contributed to the formation of sinkholes and/or swallets in or near Stockertown, Pennsylvania, and dewatering of the Bushkill Creek,” the DRN wrote.

Daniel Nugent, a spokesperson for Buzzi Unicem, said Monday that the company had not received the Delaware Riverkeeper Network’s letter.

Various state and federal agencies have noted that the Lehigh Valley has the “highest natural sinkhole occurrences in the country and has experienced sinkhole formation for centuries,” Nugent told The Inquirer last month.

Test results, according to Hercules officials, showed that just 10% of the quarry’s water came from the creeks.

Maya van Rossum, leader of the Delaware Riverkeeper Network, said the goal is simple.

“What we want them to do is stop violating the law," she said, "and stop killing the creek.”