An environmental group is pressuring Miami-Dade County and federal agencies to reach an agreement on fixes to the county’s aging water and sewage system — sooner, rather than later.

Biscayne Bay Waterkeeper has filed a notice with the county, and state and federal environmental protection agencies, saying it intends to file a lawsuit in 60 days because the county has violated several provisions of the federal Clean Water Act.

The group says the notice will force the federal agencies to either sue the county within the 60 days, or conclude ongoing negotiations over how Miami-Dade will overhaul its crumbling water and sewage system.

The county has been negotiating with the Environmental Protection Agency and U.S. Justice Department since May, when the agencies said the county was violating the Clean Water Act and proposed a consent decree.

Miami-Dade’s 13,000 miles of sewer and water pipes are decaying, as are its six water treatment plants. Large spills are common, and an important pump station in Coconut Grove has reached capacity, forcing the county to impose a moratorium on new sewer hookups in the area.

County leaders have said they expect negotiations with the EPA to continue through the spring. But County Mayor Carlos Gimenez has said he expects work on the aging system to begin sooner, with $100 million already available and another $300 million worth of bonds scheduled for sale.

Assistant County Attorney Henry Gillman, who represents the water and sewer department, said Tuesday he could not immediately respond to the litigation notice.