TUCKERTON, N.J. - For years, a cadre of sportsmen, boaters, scientists, and other observers told anyone who would listen that big problems were brewing in Barnegat Bay.

They could see changes, they insisted: dwindling fish populations, murky water, and declining plant life in the back-bay waters that spawning species use as a nursery. Some said they could even smell the problem, as the "healthy, earthy" marsh mud scent turned to something else entirely.

Many bay users - from environmentalists to fishermen - attributed problems to the Oyster Creek nuclear power station, which daily sucks up and then releases 1.4 billion gallons of water and alters the bay's temperature and other water conditions.

Some scientists, however, say the problem is lawn care. The bay is like a garden getting too much fertilizer from nitrogen pouring in from storm-drain runoff and other sources. The high nitrogen levels have caused healthy species to decline and the pollution-tolerant - such as the stinging jellyfish that have overrun some of the bay's tributaries - to thrive.

After years of study by the New Jersey Department of Environmental Protection, Rutgers University, and various grassroots groups such as Clean Ocean Action and ReClam the Bay, state legislators last week passed three bills aimed at protecting and preserving the brackish waterway.

In a separate action, the state also agreed to a deal with Exelon Corp., which operates Oyster Creek, to close the nuclear plant 10 years sooner than expected, in 2019. In exchange for the early closure, Exelon will not be required to build expensive cooling towers that would have reduced the temperature of water emissions.

Many of those who live on, work on, and study the 30-mile-long Ocean County waterway, which extends from the Point Pleasant Canal to the Manahawkin Bay, applauded the remedies as overdue.

"For years, we've been saying the bay is dying," said Capt. Jack Shea, 64, who has operated fishing charters here for 18 years - never missing an opportunity to educate his passengers about the ecologically sensitive Barnegat.

"The bay looks, even smells, different than it did 15 or 20 years ago. It's not someplace you want to swim anymore. For a long time, people have been saying something needs to be done, and I'm glad to see something finally is happening," Shea said as he prepared for next season on his 26-foot boat, Rambunctious.

One of the laws - perhaps the toughest in the nation, legislators say - will restrict the sale of certain types of fertilizer. It is expected to ultimately reverse the declining conditions in a place that had once been a center for commercial fishing and oyster harvesting. The bay also was long considered a sportsman's paradise, attracting hunters and fishermen from all over the globe.

But in recent times, the lucrative fisheries and sporting opportunities have all but disappeared.

"There was a time out on the Barnegat Bay on a boat when you didn't know whether you should grab your shotgun to get the flocks of ducks flying over or pull in that line with a striper on it," said Bob Creamer, 92, of Tuckerton, who gave up sporting when his eyesight weakened, which was about the same time he noticed the bay declining.

"You had to be quick if you wanted to take in all that bay had to offer," he said.

Other bills aimed at improving water quality that passed last week include a requirement that construction crews restore soil to its original condition after a project is completed so that storm water will soak back into the ground instead of running off hard-packed dirt and into sewers.

Another new regulation implores the federal Environmental Protection Agency for technical assistance in determining a safe daily-nutrient level in the water and requires the state DEP to identify and upgrade malfunctioning storm drains in Ocean County as a way to reduce the bay pollution.

At the heart of the regulations, however, is the requirement that at least 20 percent of the nitrogen in fertilizer sold in New Jersey be a slow-release type that will prevent the material from washing easily into waterways. Nitrogen is a major pollutant that spurs algae blooms that eat up the oxygen levels in the water, depriving fish and other aquatic life of the vital component.

Although designed for Barnegat Bay, the laws will benefit all New Jersey waterways, said Assemblyman John McKeon (D., Essex).

"This will mark the beginning of the turnaround of Barnegat Bay. Shame on us for allowing it to get to where it is today," McKeon said.

Over time, the new legislation should go a long way toward returning the bay to where it should be, said Lisa Auermuller, watershed outreach coordinator of the Jacques Cousteau National Estuarine Research Reserve here.

"What this tells us is that people have been listening to what we've been saying about this after years and years of educating municipal officials and citizens of the state about the importance of doing the right things . . . when it comes to fertilizer," Auermuller said. "Now people at a higher level of government recognize there is a problem here."

Contact staff writer Jacqueline L. Urgo at 609-652-8382 or jurgo@phillynews.com.