About Mark Mattson

About Mark

One specific goal shapes Mark Mattson’s life and work: swimmable, drinkable, fishable waters for everyone. 

Mark was born in Kitchener, but spent most of his life off the coast of Kingston, Ontario. He spent his childhood summers on Wolfe Island, swimming and fishing in Lake Ontario’s sparkling waters. There, his love of water was born. 

Growing up in a family of lawyers filled Mark with a strong sense of justice and a passion for fairness and individuals’ rights. Mark felt privileged to grow up with swimmable, drinkable, fishable waters. Now, he fights for that right for everyone.

After graduating from Windsor Law School in 1988, Mark worked at Osler, Hoskin and Harcourt, one of Canada’s oldest law firms. Mark left Osler for private practice, focusing on criminal defence.

In 1991, Doug Chapman invited Mark to take on his first environmental case: a landfill expansion in Storrington, just outside of Kingston. Mark and Doug went into practice together, with Mark helping Doug fight some of Canada’s most notorious corporate polluters. Over the years, they set a number of legal precedents, convicted polluters, put an end to projects destroying fish and fish habitat, and forced corporations to clean up contaminated sites. 

Doug and Mark created the Environmental Bureau of Investigation (EBI) in 1996. This volunteer-based effort identified and prosecuted environmental offenders over five precedent-setting environmental cases. Led by Mark, the grassroots collective was comprised of community activists, scientists, and lawyers who collected evidence against water polluters in their spare time. Mark volunteered his skills as environmental investigator and prosecutor to the cause, working on cases in Kingston, Hamilton, Deloro, Moncton, and Montreal. 

By 1997, Mark had shifted the focus of his legal work to public and nonprofit advocacy. After years in the courtroom, he began to devote more time to developing institutions and volunteer networks that could restore and protect watersheds for generations to come.

In 2001, he founded Lake Ontario Waterkeeper, an organization that gives meaning and force to environmental laws. Lake Ontario Waterkeeper grew and its work expanded beyond Lake Ontario, becoming a global movement of people working for water. In particular, Mark has championed the growth of ground-breaking programs including the Clean Water Workshop, Swim Guide, and Great Lakes Guide. 

Click here for more on our organization’s history and impact.

Over the years, Mark has appeared in provincial and federal courts, federal government committees, Ontario government committees, as well as city councils. He speaks frequently to the media about issues affecting water in Canada and has appeared on national news programs for all major networks, CBC Radio programs, as well in the pages of the Globe & Mail, National Post, and Toronto Star.  

In 2010, Mark won the Toronto Community Foundation’s Vital People Award, which supports leaders who are making outstanding contributions working at not-for-profit organizations.

Swim Drink Fish, of which Mark is president, was created to oversee this work outside of Lake Ontario watershed. Mark remains the organization’s full-time Waterkeeper and President to this day and sits on the board of directors of four Waterkeeper organizations in the U.S. and Canada. Mark has served as a Board Member on the Waterkeeper Alliance Board for 19 years. He is also a Guardian in Ontario’s Great Lakes Guardian Council.

In the past, Mark served on the boards and committees of the Environmental Bureau of Investigation, Canadian Water Issues Council, Great Lakes United, and Great Lakes Water Quality Board for IJC. Mark has been a member of the Law Society of Upper Canada and an invited member of the Stakeholder Advisory Committee, Urban Park and Waterfront Trail at Ontario Place. He has acted as counsel for public interest groups at more than 50 hearings, including the Walkerton Inquiry, the International Water Tribunal, and the Ontario Energy Board.  

Mark has been involved in notable cases, investigations, and prosecutions, such as Fletcher v. City of Kingston, Lukasik v. City of Hamilton, Environment Canada v. Technoparc, Environment Canada v. City of Moncton, Lafarge Canada v. Ontario Environmental Review Tribunal, and Edwards v. DTE. Other notable cases include the Deloro Mine case against Ontario and the case against Castonguay Blasting Ltd., which made it to the Supreme Court.