Riding a kayak on the Hudson River is a great way to escape the madness of New York City, but Sandy Sobanski could do without the raw sewage and used condoms that float by her rig after heavy rainstorms.

The 25-year resident of Hoboken, N.J., donned a battered orange life jacket, picked up a paddle, and headed to the steps of City Hall to get her message out yesterday, along with a group of other environmentalists and a City Council member, David Yassky, a Democrat of Brooklyn. They claim that a tentative agreement with the state Department of Environmental Conservation – for which the public comment period ends today – would release the city from a promise to build nine huge and costly holding tanks for sewage, which would capture excess rainwater runoff and raw sewage currently dumped into the Hudson and other city waterways during heavy rainstorms.

“It’s just gross,” Ms. Sobanski said. “And if they go with this policy, it’s going to be pretty bad.”

In the last six years, the city has made significant progress in cleaning up its notoriously fetid waterways. Fish have come back to the Hudson, along with a growing population of mollusks. Boaters have taken to the water in droves, new parks are in the works, and the Bloomberg administration has worked to expand the greenway ringing the five boroughs. It’s all part of a nationwide movement punctuated by the passage of laws like the federal Clean Water Act, which required states to enact new environmental standards and provided some grants for sewage treatment plants.

The city remains out of compliance with state water quality standards, however, and it has had a tough time coming up with enough money to deal with the problems. In 1992, the city agreed to pay a $250,000 fine and meet the standards within 12 years by building the nine new storage tanks. Only two have been built, though. The new agreement does not mention any new tanks, or what will replace them, and it would allow the city to continue to violate the standards with nothing more than a $2 million fine for the next 12 years, according to a senior attorney at the environmental group Riverkeeper, Reed Super, leaving it unclear if the city ever intends to meet the standards.

A spokesman for the city Department of Environmental Protection, Charles Sturcken, pointed to the city’s successes at improving the water quality while acknowledging there is more to do. The tanks simply cost too much, and the money would be better spent on research to process more sewage in the city’s existing treatment plants, he said.

“All the water is fishable and swimmable, and we have not had a public beach closing due to a storm in eight years,” Mr. Sturcken said. “We didn’t get to where we said we were going to get to in 1992 because of the cost. They want us to build tanks everywhere. Do you want a tank in your back yard? I believe we can reach these standards in 10 years by focusing on developing the science to treat the sewage.”

Mr. Yassky, chairman of the council’s Waterfronts Committee, expressed skepticism at that projection.

“We are here because 12 years later, they still haven’t fixed the problem,” he said. “I asked the head of the agency at a hearing if they were ever going to be able to get to where they said they would get, and he could not answer me.”

A spokeswoman for the Natural Resources Defense Council, Alice Chase, said water polluted by sewage or garbage sickens millions of Americans each year, and she called the tentative agreement an “entrenched city and state bureaucratic response.”

More than 6,000 miles of pipes snake beneath the city, carrying sewage and rainwater to treatment plants. On average, a total of 27 billion gallons overflows from them and is dumped, through 460 drainage pipes, directly into the waterways each year, environmentalists said.