Groton - Most of the few boaters around Brewer Yacht Yard Friday morning were cleaning and buffing their vessels, which were still out of the water on stands from the winter. But the 23-foot work boat manned by brothers Constantine and Harrison Macris maneuvered across the Mystic River to the docks to refuel as it had throughout the winter.

As summer approaches, the Macris brothers and their father, Dean, who run the nonprofit pump-out boat service that operates on the Mystic and lower Thames rivers, were preparing to triple their in-water fleet. They will launch their two other boats before Memorial Day. One will join the first in operating out of the Brewer marina in Mystic, while the third will operate out of the Gales Ferry Marina.

Last year, the three Coastal Environmental boats kept 80,000 gallons of waste out of local waters from 4,328 boat visits, bringing the sewage that would have gone into the rivers or Sound to shoreside facilities connected to municipal wastewater treatment plants.

"Our job is to make doing the right thing as easy as possible," said Constantine Macris, the president of Coastal Environmental Services. His brother is secretary-treasurer and program-operations manager, while the older Macris is vice president of the four-year-old nonprofit.

The service, which operates on an annual budget of $200,000, is offered free to boaters, who simply call or email and request a pump out. Once the pump-out boat arrives, sidles alongside the vessel and hooks up the equipment, emptying the tanks takes three to five minutes, Constantine Macris said.

Federal grants cover 75 percent of the program's cost, while the rest is paid for through private donations and contributions from the towns where the boats operate. Dean Macris said that while donations already come from boaters who are the most direct beneficiaries, others who enjoy the river and Sound should realize they're benefiting, too.

"We're making the river healthier for people in kayaks, for fishermen, for people who swim in it," he said. "Donations will help us to continue to fulfill our mission."

The three vessels are part of a network of pump-out boats and stationary pump-out facilities at marinas across the Connecticut side of Long Island Sound.

This network has fostered a cultural shift among boaters away from the once common practice of discharging raw sewage from their vessel tanks into the Sound, said Kate Brown, who oversees the pump-out program at the state Department of Environmental Protection's Office of Long Island Sound Programs. Now, four years after Connecticut waters of the Sound became an Environmental Protection Agency "no discharge zone," boaters are in the habit of calling for a pump-out by pulling up to a stationary facility, and even report when they see other boaters not doing the same, she said.

This summer, the New York side of the Sound is also expected to become a "no discharge zone," said Mark Tedesco, director of the EPA's Long Island Sound programs, after that state built its own network of pump-out boats and shoreside equipment.

"It'll lead to a consistent policy on Long Island Sound, which is a good thing," he said.

Water quality problems in the Sound, he said, "are not caused mainly by boaters' waste, but it is a contributor to it."

Overall, Tedesco said, water quality in Long Island Sound has gradually improved, thanks to upgrades in the sewage treatment plants that empty into the estuary, the pump-out program and other measures. Connecticut, in fact, is ahead of schedule in approaching nitrogen reduction goals by 2014, Tedesco said.

"They're still trying to reach the goal, though," he said. While the impact of the pump-out program on water quality has not been specifically quantified, he said, "the expectation is that if you remove a source of nutrients and pathogens, there will be benefits."

The Macris family began the service by running the pump-out boats for the town of Groton. A few years ago, when the town decided it no longer wanted to be involved, the nonprofit was formed so the service could continue. Partners include Mystic Aquarium and several marinas. Coastal Environmental trains and employs 10 part-time workers to run the boats for the summer, providing jobs that require lots of serious seamanship skills but are also rewarding to those who want to help the environment.

"It's dirty, but it's green," said Dean Macris.

For information about Coastal Environmental Services, visit: www.cespumpout.com.

For information on the pump-out program and the no discharge zone, visit www.ct.gov/dep/cwp/view.asp?a=2705&q=323706&depNav_GID=1711 or www.ct.gov/dep/cwp/view.asp?a=2705&q=323816&depNav_GID=1711

j.benson@theday.com

Local marinas with pump-out facilities

Old SaybrookBrewer Ferry PointRagged Rock MarinaSaybrook Point Marina

LymeReynolds Garage & Marina

Old LymeState DEP Marine Headquarters

East LymeNiantic DockominiumsPort Niantic MarinaThree Belles Marina

WaterfordNiantic Bay Marina

New LondonBurr's Yacht HavenCrocker's BoatyardThamesport Marina

NorwichThe Marina at American Wharf

GrotonCity of Groton, Wastewater Treatment FacilityMystic ShipyardNoank ShipyardNoank Village BoatyardPine Island MarinaShennecossett Yacht ClubSpicer's Noank Marina

StoningtonBrewer Yacht Yard at MysticBrower's Cove MarinaDodson BoatyardMystic River MarinaMystic SeaportMystic Shipyard EastNorwest Marine

WesterlyAvondale Boat Yard

Southeastern Connecticut pump-out boats:Lower Connecticut River Pumpout Boat, Essex (860) 463-9753; VHF Channel 72Save the River/Save the Hills Niantic River Pumpout Boat, Niantic (East Lyme, Waterford): (860) 287-2774; VHF Channel 68;

www.savetheriver-savethehills.org/pumpoutprogram.htmlCoastal Environmental Services Pumpout Boat, Mystic and lower Thames rivers: (860) 514-7664; VHF Channel 68;

www.cespumpout.orgDodson Pumpout Boat, Stonington (860) 435-1507; VHF Channel 78.Town of Westerly Pumpout Boat: (401) 3488-2572; VHF Channel 8.