The Environmental Protection Agency says 87 percent of the nation's publicly owned sewage treatment plants met the July 1 clean water deadline, but 423 cities still have problems.

EPA Administrator Lee Thomas said Wednesday that compliance by 1,055 cities - about 87 percent - means 95 percent of the total sewage processed in the United States receives special treatment that protects public health as well as fish and aquatic life. About 108 million citizens are served by the plants.But 423 cities, roughly 13 percent of the plants serving 10,000 or more people, missed the July 1 deadline for legally required pollution cleanup. Of that number, 235 cities are on court-imposed timetables leading to compliance, but court action is pending against 188 cities that have the most serious problems with compliance.

Marzulla said 35 new lawsuits have been filed in the past six months, including ones against Akron, Ohio, and the Minneapolis-St. Paul area. He said 125 lawsuits have been filed by the federal government against municipalities since 1984. Settlements have been recently reached with Shreveport, La.; Sarasota, Fla.; York, Pa.; Pasadena, Texas; Hudson County, N.J.; and East Chicago, Ind.

Thomas attributed the 87 percent compliance rate to voluntary compliance and to federal and state enforcement efforts.