Founder and President

Mark Mattson is a prominent environmental lawyer who has spent the last decade building a network of successful community-focused environmental organizations across Canada. His love of water stems from his childhood summers swimming and fishing on Wolfe Island, near Kingston.                    

Born into a family of lawyers in Southern Ontario, Mark grew up with a passion for fairness and individual rights. He has worked in the private, public, and nonprofit sectors over the course of his career. As a prosecutor, first for government and then for NGOs, Mark was part of ground- breaking private prosecutions and administrative cases against major industrial polluters.

After ten years in the courtroom, Mark began to devote more time to developing institutions that will restore and protect watersheds for generations to come. He founded Lake Ontario Waterkeeper in 2001 and remains the organization’s full-time Waterkeeper and President to this day. Mark sits on the board of directors of four Waterkeeper organizations in the U.S. and Canada.

When he transitioned from full-time lawyer to full-time Waterkeeper more than ten years ago, Mark was able to unite his commitment to social justice with his passion for water. He has spent the last decade working to uphold the ideal that each and every person has a right to swimmable, drinkable, fishable water.


Founder and Vice-President

Krystyn Tully has been organizing community events and organizations since her days as a high school student in Oshawa, Ontario. She helped Mark Mattson launch Lake Ontario Waterkeeper in 2001 and serves the organization to this day.

Over the course of the last decade, Tully helped to organize a wide range of fundraising events grantwriting campaigns that helped to raise $2-million for Waterkeeper’s work. She also spearheaded the creation of Swim Guide, a mobile app and website that connects people to clean, local beaches as well as Drink Guide, an app that documents drinking water advisories across Canada. These apps are now used by more than 100,000 people in Canada and the USA.

Since co-founding Lake Ontario Waterkeeper with Mark Mattson in 2001, Tully has written or edited more than 400 articles about water and environmental policy. She has appeared before numerous municipal, provincial, and federal government committees. For four years, she coordinated a mentoring program that connected aspiring lawyers with communities facing environmental challenges. For two years, she was editor and co-host of a weekly radio program. In 2012, she wrote a series of features on beaches for blogTO and became a regular contributor to Huffington Post.

Through Ryerson University’s part-time degree program, Tully has received extensive education in Public Administration and Governance, with a specialization in nonprofit sector management. She was profiled in NOW Magazine’s “Class Action” feature in October, 2012.


Parker Muzzerall

Swim Guide Assistant

As Swim Guide Assistant, Parker works directly with a global network of over 80 environmental organizations and 7000 beaches to maintain the daily operations of the Swim Guide app and website. He also contributes to Swim Guide’s blog, Beach Basics, and helps promote Swim Guide across social media platforms.

Parker joined Swim Drink Fish in the fall of 2017 after completing a degree in Sociology and Political Science at Dalhousie University, where much of his work focused on Indigenous and Environmental issues. His honours thesis examined how the values of climate justice get represented in North American media. Having been involved in social and environmental activism for years, Parker is excited about working towards a swimmable, drinkable, fishable future for everyone.

Parker grew up in Nova Scotia’s Annapolis Valley, and spent his summers at his family cottage on one of Nova Scotia’s many freshwater lakes. He loves to canoe, kayak, and swim.



Technical Advisor

Dylan is the in-house technical advisor to Lake Ontario Waterkeeper, dealing with information technology resources and technical projects. Dylan helped to build a variety of Lake Ontario Waterkeeper projects, including, Swim Drink Fish Music, Swim Guide's website and appDrink Guide app, and the Watermark Project

Dylan has been working in the field of information technology for almost 20 years. He was the technology director of one of the GTA's early independent internet service providers and since 1998 has been the Chief Technology Officer of a successful e-commerce company.



Swim Guide Program Manager

As the Program Manager for Swim Guide, Gabi supports nearly 50 public and nonprofit organizations that contribute water quality information to the Waterkeeper Swim Guide app and website. Gabrielle also manages information for over 7,000 beaches in Canada, the US, Mexico and New Zealand to ensure that Swim Guide users have access to the most current water quality data.

Gabrielle joined LOW in 2014. She is a Southern Ontario native and grew up on the banks of the Welland Canal. She earned her undergraduate degree from Trent University in First Nations Studies and her Masters in Canadian History from Lakehead University. As part of her research she studied the environmental history of Aboriginal fisheries in Northwestern Ontario. For the past three years, Gabrielle has volunteered at Israel’s Sea Turtle Rescue and Rehabilitation Centre. There she cared for sick and injured sea turtles, monitored sea turtle nests and hatchlings, and worked to promote the protection of the Mediterranean’s marine environment.

Gabrielle is an avid open water swimmer and loves her native watershed.