To dip or not to dip? Torontonians can be forgiven for being cowardly when it comes to swimming in the lake that defines their city's southern boundary. With so many communities and so much industry on its shores, Lake Ontario has developed an iffy reputation when it comes to its cleanliness.

Since 2004, the group Lake Ontario Waterkeeper has been reporting on summer beach closures, first with information they got from their own monitoring efforts and then by putting pressure on municipal governments to make the information they gathered accessible. The organization then creates a one-stop-shopping spot for daily or weekly reports on the health of almost 100 beaches surrounding the lake, including Toronto's 12 (at most times) swimmable beaches. The Lake Ontario Waterkeeper (L.O.W.) beach report has become so popular that groups in other parts of North America are looking at ways to adapt it for their own beaches and L.O.W. itself is in the process of turning it into a smartphone application.

The beach reports are handy, but they're also an ingenious form of environmental activism. Bucking a long history of communities turning their back on Lake Ontario, Toronto-based L.O.W. treats people like the lake-side residents they are. The not-for-profit may have made its name arguing for increased protection of the lake in tribunals, hearings and courtrooms, but it's made bigger waves changing the hearts and minds of people who live close to the lake. It has done so by taking an issue that's usually very complicated -- competing jurisdictions, convoluted legislation, reliance on scientific experts and fecal-coliform counts -- and made it simple and heartfelt.

"We celebrate the right to swim and encourage the public to turn their environmentalism into something more than just conserving, doing things less or stopping polluters. There's something they can do in just enjoying the water which environmental laws were meant to protect," says Mark Mattson, who this summer won a Green Toronto Award for his efforts.

Armed with degrees from Queen's and the University of Windsor, Mattson started working in environmental law in 1996, when the Mike Harris Conservatives were making drastic changes to the province's environmental policies. After meeting Robert F. Kennedy Jr., a fellow environmental lawyer as well as a member of the powerful Kennedy clan, Mattson was persuaded to launch L.O.W. At that time, Kennedy had just founded Waterkeeper Alliance, an international organization intended to help connect local grassroots Waterkeeper groups that were springing up around the U.S. Mattson quickly realized that environmental law and environmental awareness could make excellent bedfellows. Ten years later, L.O.W. has seven employees a slate of experts it brings in on contract to help with its work, and a budget of $600,000.

In the courtroom, L.O.W.'s highest profile win so far was 2008's Lafarge case. The construction-materials manufacturer wanted to avoid an Environmental Review Tribunal hearing into its plan to use used tires, shredded solid waste, pelletized municipal waste, and meat and bone meal waste to fuel its operations. Fearing the project would harm the Lake Ontario ecosystem, L.O.W. joined other opponents to force a hearing. They won. After the decision, Lafarge withdrew its proposal.

"The Lafarge case breathed life into Ontario's Bill of Environmental Rights," says Rick Lindgren, a lawyer at the Canadian Environmental Law Association. He was the lead lawyer on the Lafarge case and has worked with Mattson since the days before Waterkeeper. "It really reaffirmed the importance of public participation in environmental decision-making. I think it will hold the government more accountable for some of the environmental decisions that are being made these days."

Not only did L.O.W. get itself a useful legal precedent in Lafarge, it found an ally in Gordon Downie, who was one of the lead plaintiffs. The Tragically Hip frontman helped put L.O.W. on track as it sought to connect with people on a level that didn't require having a master's degree in environmental science. Nothing cuts to the heart of things quite like music. Launched last year, L.O.W.'s SwimDrinkFishMusic.com website features artists like Downie, Dave Bidini and, perhaps not surprisingly, Great Lake Swimmers, who offer fresh tracks to members of the music club. The result is an artist-fan synergy around clean water. Navigating indie music and navigating water issues are made equally accessible, rather than something pursued by marginal zealots.

As L.O.W. reaches out through its website, music events like August's Wolfe Island Music Festival,  podcast, apps and other social media, Mattson and his team have placed their "Swim Drink Fish" concept, sometimes illustrated with a zippy logo, front and centre.

"Mark has boiled it down to make it so easy," says Marc Yaggi, deputy executive director of Waterkeeper Alliance. "Everyone recognizes the words swim, drink, fish and knows what they mean. How can you have a problem with them? He's able to make environmental activism positive. Not everything is about the sky falling."

In the early days, Mattson, who is almost 50, says he put too much faith in government to enforce its own environmental laws. He realized that too much of the debate was happening behind closed doors, out of the eyes of the public. Citizens were left to assume that because they weren't hearing about issues, everything was okay.

"There comes a time when people get so disconnected from their environment," says Mattson. "but they can only go so low. People are starting to understand the vulnerability of our water."

There are times when the way forward is not so clear. Mattson has been torn about some of the proposals for wind-generated electricity that have emerged out of Ontario's Green Energy Act, introduced last year. He came out against the proposed locations of some projects, particular on Main Duck Island and in Lake Ontario itself, off the Scarborough Bluffs. His support for wind energy in principle was overruled by what he saw as poor planning.

"Ontario left so much of [the decision-making] in the hands of the companies, who are going to put the turbines where it's cheapest," says Mattson.

Awards and increased recognition have not slowed Mattson down. With 38 open files on legal cases, a music club to run and beach-report apps to launch, there's no shortage of things to do. Asserting your rights to take a dip in Lake Ontario might be the beginning of water activism, but it's not the end of it.

Paul Gallant is a Toronto-based freelance writer who lives in the emerging Brockton Triangle neighbourhood.