With over 1,300 lakes and countless streams and ponds, Muskoka is a place where water quality is taken seriously. The surface water and the underground aquifers are vital to the health and beauty of Muskoka’s lands, wildlife, and people.

But over the years, the watershed has faced many challenges to its own health, including acid rain, garbage, sewage, calcium decline, and more recently road salt. Each of these threats has a knock-on impact on everyone and everything living in or around the region.
To understand what’s happening in our watershed – and to address problems as quickly and effectively as possible – a dedicated network of people takes samples, records data, and collaborates with each other.

Groups like the Muskoka Lakes Association, Friends of the Muskoka Watershed, the Muskoka Watershed Council, and the District of Muskoka all take on different roles. Together with other partners, they share vital information and help plan solutions to combat the issues.
It starts with dataThe Muskoka Watershed Council (MWC) is a key source for historical data on water quality. They help provide a baseline as the information collected through sampling and testing by the other organizations is sent to them.

“We’ve maintained a consistent monitoring program back to 2003, but we actually have data on many lakes going back to 1980,” says Rebecca Willison, a watershed planning technician with the MWC and the District of Muskoka.

A District of Muskoka initiative, the MWC was founded in 2001, becoming an incorporated and independent non-profit organization in July 2019. The MWC is an advisory body and not a regulatory or enforcement agency. It makes recommendations to municipal governments, to decision-makers, to managers, and to the public on ways to protect and restore the resources of the area’s watersheds.

That includes working with agencies outside the boundaries of Muskoka. The watershed (the lands that all drain into the Muskoka river system) extends into Algonquin Park, Haliburton, and Parry Sound District, covering 5,100 sq. kms of land.

The MWC represents key interests and stakeholders, ensuring a comprehensive look at watershed issues, regularly communicating with other active groups and individuals.

“We have 45 years of data and that’s not common,” says Willison. “It’s very interesting and exciting to see our data used in things like the Muskoka official plan.”

Getting saltySome of that data has been used to understand how much of an impact road salt is having, and which lakes are most affected.
Ecologist Neil Hutchinson Ph.D. is leading salt research with the Friends of the Muskoka Watershed (FOTMW). A longtime Muskoka resident who recently retired from running his own water consulting company, he has been concerned with how road salt – sodium chloride – is impacting the watershed for years.

Thanks to years of data from the MWC, Hutchinson can see that chloride concentrations are high and increasing in many lakes. “I’d like to emphasize how useful the District of Muskoka’s lake sampling program is,” he says. “They’re building a long term record of the same process, the same methods, the same sampling in the same place year after year in in approximately 200 lakes . . . It’s just so valuable to have that long term record and we really appreciate it as watershed scientists.”

Hutchinson and FOTMW have focused their research on three lakes in the Gravenhurst area: Jevins Lake, Gull Lake, and Muskoka Bay on Lake Muskoka. With support from volunteer “citizen scientists,” including a dedicated group from the Gull and Silver Lake Residents Association, the team has been testing lakes, ponds, and streams for chloride levels since 2021.

Their first study, published in early 2025, shows that chloride levels have been rising steadily, and in some areas are already high enough to be damaging organisms that live in the lakes. By looking at specific streams and creeks, they’ve also been able to determine that the salt isn’t just coming from roads and highways: private parking lots are also a significant contributor.

Regardless of the source, increased salinity can kill zooplankton, including species that feast on algae. Without those vital creatures, algae can grow unchecked. Salt can also cause corrosion to pipes and other metal structures, as well as degrading water quality for drinking, bathing, and other uses.
All the findings point to a need to reduce the overuse of salt for unnecessary applications, explains Hutchinson.

“It’s really hard on infrastructure made from concrete and steel,” he says. “It’s also very hard on the paws of our dogs walking around town. And once it gets into the lake, it’s very hard on sensitive aquatic life in our lakes in Muskoka.”

Lakes in this region have very low levels of calcium, he explains, which makes aquatic creatures more susceptible to harm from salt. Calcium levels have been historically low in lakes on the Canadian Shield, but those levels dropped even more during the era of acid rain. While acid rain has been greatly reduced, it could take centuries for calcium levels to recover naturally.

To give the process a boost, FOTMW launched the AshMuskoka project, using residential wood ash – a calcium-rich material that many people just send to the landfill.

Scientists working with FOTMW have shown that a single treatment of wood ash in the forest supplies critical nutrients to trees and other plants. As calcium-rich leaves decay in the fall, the nutrient makes its way into the soil, eventually running off into lakes and rivers or percolating down into underground aquifers.

Hutchinson says wood ash is even a great alternative to using salt on driveways in the winter but does admit it can be messy if spread too much. “I use it on my driveway, but of course you don’t for the last little bit or you’re just tracking into the house,” he says.

He recommends using sand rather than salt whenever possible, since it has much less of an impact. If you do use salt, use it sparingly. “A small 10 oz cup will do most residential driveways. It’s important to look around at how much you really need.”

The FOTMW has just launched a Salty Muskoka project which is getting the message out about using less salt. By meeting with municipalities across the region, the group has been encouraging them to recognize that salt is a threat, and to adopt different application practices on municipal roads, sidewalks, and parking lots. That can include using brine instead of rock salt, which is both cheaper and more effective in many conditions. Or adopting different strategies depending on the weather conditions.

Ups and downsSalt and calcium are just two of the issues that can affect water quality. Phosphorous and bacteria levels can also have a big impact, which is why the Muskoka Lakes Association (MLA) and other lake associations have spent years testing those.

Deb Martin-Downs, who runs water sampling for the MLA and is president of the Federation of Ontario Cottagers’ Associations (FOCA), says it’s vital to collect and share data.

“One of the biggest values is having year over year data,” says Martin-Downs, a biologist with a Ph.D. specializing in freshwater ecosystems. “The same place is sampled in the same way with the same parameters so that you can see particular changes over that time. It’s one of the things the MLA really focuses on, and it allows us to see what’s happening.”

For instance, a steady increase in phosphorus can be a sign that the lake will be prone to more algal blooms. This provides the information necessary to address a little issue before it becomes a big problem.

“Then we can flag those things for those who actually can go and do something about it,” Martin-Downs notes.

Monitoring phosphorous levels has helped move municipal policies in a significant way, prompting a raft of bylaws and regulations that ensure septic systems are updated and, in some cases, moved away from the shoreline during renovations. Since septic inspections were introduced, phosphorous levels at most test sites have been trending downward. “We’re not talking a steep decline. Just this gradual reduction.”

Other policies that help keep lakes healthy include regulations about shoreline protection, tree preservation, and preventing runoff from construction sites.
Regular testing isn’t just about long-scale trends, says Martin-Downs.

“We had one area where our bacteria numbers were through the roof,” she recalls. “We thought, ‘there’s something going on here.’ So, we contacted the municipality, and they went out checked and sure enough there were damaged septic pipes leaking into the lake. If we hadn’t been sampling water, we wouldn’t have seen that, and it could have had an even worse impact.”

For all that has been learned about lake health, it’s important to recognize that Muskoka has many lakes of different sizes, different depths, and different ecological make-ups. Some are heavily used by people, while others rarely even see a canoe. Then there’s the seasonal fluctuations caused by wildly varying weather patterns – particularly snow melt and spring rain.

“It’s hard to make generalizations across so many different lakes,” says Martin-Downs, “but we do have a few of the smaller ones that were probably always reasonably enriched with nutrients. They’re different than the big lakes.”

Regardless of the lake, though, having a buffer of native, natural vegetation on a property helps protect the lake from runoff. The vegetation acts as a filter, preventing dirt and pollutants from flooding straight into the water.

“Understand the role that shoreline integrity has,” she advises. A vegetative barrier also discourages geese, which are attracted to properties with waterfront lawns they can graze on. “Even too many geese gathering in one area for too long can negatively impact water quality as they spread bacteria.”
Report cardNo matter what is causing the disturbance in the water’s nutrient and chemical composition, or which organization collected the data, all of it is collated and stored by the MWC.

To help keep everyone abreast of what’s happening, the group creates a watershed report card every five years to help disseminate essential information on the health of the lakes and rivers in the region. The report card presents information on lake health for the region as a whole, as well as individual bodies of water – some improving, some declining. The next one comes out in 2026.

Each of the groups is also working closely with the Muskoka Discovery Centre in Gravenhurst. It has a number of exhibits on water quality, and is in the process of launching a major permanent exhibit that will help disseminate information to the public. Called Love Muskoka Sustain Muskoka, it is scheduled to open in 2026.

“Everyone has their data, and I find we’re all really good at sharing it,” explains Willison. “If you have a research question, we can get the data you are looking for. I see the watershed report card as being sort of a clearinghouse for all the data we’re collecting. It’s put into a format that is been easily accessible and understandable by the general public.”

By collecting and using data to determine alarming trends in the watershed, the people, organizations, and governments can (hopefully) make changes to protect the future of Muskoka.