Water Quality

Morrison Lake Water Quality Update May 2024

Jenny Fairbrass is managing the Eurasian Water Milfoil program.  This invasive species is arguably one of the most significant threats to our lake.  Volunteers are needed to help.

The volunteer who was taking over the Lake Steward – Environmental role has had to step back. MLRA is looking for someone to take on the role, Pete LeMoine will assist.  Reach out to speak to us about the role.

Love your Lake surveys were completed in 2022. Of the 228 waterfront properties surveyed only 95 owners have chosen to look at their results.  The survey results highlight how important a natural shoreline buffer is to lake health and how you could make minor changes to provide major benefits.  See our website for all the positive impacts of a natural shoreline.  Natural Shorelines — Morrison Lake

The Lake Partner Program has been providing decades of water quality results due to the efforts of many ML volunteers. There are 3 test sites on the lake for spring sampling and bi-weekly clarity measurements.  The sites are at the north end near the inlet river, at the deepest spot (55 feet, 17 metres) south of Bell Island and near the outlet river Morrison Creek.

In 2023 the TP (total phosphorus) levels at the input were slightly higher than at the outlet.  The average of the sites is 8 ug/l.  The average over the past 18 years is 8.5.  Like most lakes in Muskoka, the TP readings have been dropping – improving due to better environmental practices such as zero phosphate cleaning products and upgraded septic systems. TP of less than 10 ug/l is considered low nutrient level which is good.  Some years we have exceeded this so we should not relax our positive actions.

Calcium levels were destroyed by acid rain.  The Canada-United States Air Quality Agreement signed in 1991 is a great example of how a massive, seemingly impossible problem can be solved when all parties commit to the solution.  Currently, the rain in Muskoka is 40 times less acidic than it was!  It takes a long time to recover calcium levels, but we are doing OK.  ML calcium level is 4mg/l, less than 2.5 is bad.

Salt is a significant problem in many lakes and in Gravenhurst Bay.  Primarily due to road salt application on roads, driveways and commercial lots.  Our current readings are 6.6 mg/l. Our 10 year average is 5.9 so lets not keep increasing.  Greater than 10 mg/l can harm the very small creatures important to lake ecology.

To learn about how to help enhance and protect our water quality review the Environmental section on our website. If you have ideas for improvement and/or want to get involved contact us at mlraexecutive@gmail.com

Every cottage should have a copy of the Living in Cottage Country book on their coffee table.  They are available for $20.  Contact mlraexecutive@gmail.com to place your order.