CLARKSVILLE (AP) — A Tennessee city is defending itself against a lawsuit over sewer discharges into the Cumberland River.

Clarksville Mayor Joe Pitts said in a Wednesday news release that even if 24 million gallons (91 million liters) of sewage had been released over the past five years, as the lawsuit claims, it would be "a really small drop in a great big bucket," The Leaf-Chronicle reported.

Pitts released the statement in response to a lawsuit filed in federal court in Nashville on Friday by Tennessee Riverkeeper. Riverkeeper said in the lawsuit that the city is violating its discharge permit by allowing raw sewage to overflow into the river, with 412 violations in the last five years.

The suit also stated that at least 17 of those violations should have triggered a moratorium on new sewer connections.

In response, Pitts said the city has spent $130 million over the past nine years on sewer plant upgrades.

"The city is committed to clean water and strives to comply with all state and federal wastewater regulations," Pitts said in the statement. "And while the city does not admit to any unauthorized discharges, citizens should understand the context of what this lawsuit claims. Even if 24 million gallons of wastewater reached the river over five years, Clarksville Gas & Water would have managed to capture 99.899% of the total wastewater created in this time frame."

Attorney William L. Penney, representing the city, sent a letter to Riverkeeper stating that the city's combined sewer overflows are permitted under its current Tennessee Department of Environment and Conservation permit. He added that the city has budgeted about $7.5 million to improve its performance.

The city said it plans to "mount a vigorous defense" against the lawsuit.