NEW HAVEN >> The biggest challenge to reducing the high nitrogen levels in Long Island Sound: A one-size solution does not fit all.

This was the conclusion environmental advocates, Sound School students and teachers, and U.S. Sen. Chris Murphy, D-Conn., came to at a roundtable discussion Thursday.

“I’d like to leave here a little bit smarter so I can be your advocate in Washington,” Murphy said to kick off the discussion about how high nitrogen levels are contributing to low water quality in the Sound. “We have a lot of work to do.”

The need for this group discussion was sparked by the recent release of the U.S. Environmental Protection Agency’s nitrogen reduction strategy for Long Island Sound, Murphy said. He wanted to hear from stewards of the Sound how he could best be an advocate in Washington as this strategy turns into action.

High nitrogen levels in the Sound can lead to fish die-offs and harmful algae blooms. Last summer, more than 100 terrapin turtles died as a result of high nitrogen levels, according to Roger Reynolds, legal director for Connecticut Fund for the Environmental/Save the Sound.

“The Long Island Sound is very much under distress,” Reynolds said, noting nitrogen flows to the Sound mostly from water-treatment plants, combined sewer overflows, lawn fertilizers and storm runoff.

The EPA strategy states that scientists need to understand where the nitrogen is coming from before developing plans to mitigate the amounts flowing into the Sound. Reynolds said the EPA has laid out an aggressive timeline of one year for understanding these nitrogen problems.

“To do this, they are going to need resources,” Rey­nolds told Murphy. “This is a really critical time.”

Reynolds added that the risks to the Sound posed by climate change are compounding the effects of the high nitrogen levels.

After discussing major concerns of high nitrogen levels in the Sound, with some input from Sound School students about some of their own research on the topic, the group turned to finding solutions for how to regulate nitrogen outputs once the EPA understands how much nitrogen is coming from which sources.

But this isn’t a one-size-fits-all problem, advocates told Murphy.

“If you have 1,000 discharge sites (in one city), you need to regulate it differently than if you have 100,” said James O’Donnell, professor of marine sciences at the University of Connecticut. “There needs to be different systems.”

“There’s not one solution because there are lots of problems,” O’Donnell said.

O’Donnell, also the executive director of the Connecticut Institute for Resilience and Climate Adaptation, said developing different nitrogen-reduction plans for varying regions might cost a little more, but the benefits will far outweigh those costs.

Other environmental advocates spoke up about reduction efforts that may not require legislative action or oversight.

Margaret Miner, executive director of the Rivers Alliance of Connecticut, said reducing nitrogen levels from fertilizers could be done with more advocacy and educating the public.

Miner also advocated for localized plans to reduce nitrogen outputs into the Sound.

Murphy agreed that while localized nitrogen-reduction plans might cost more to develop, they would have “enormous payoffs down the line.”