• Nepahwin Lake Watershed Stewardship Group

Our Call to Action:

LOOKING AFTER OUR WATER QUALITY


The Nepahwin Lake Field Summary 2021: The not so good news

Taylor Menard, Lake Water Quality Program Coordinator, Environmental Planning Initiatives, Planning Services, City of Greater Sudbury presented our lake water quality data for 2021 at the November 3, 2021 meeting.

Of concern is Nepahwin Lake’s decreasing water clarity. Secchi depth, a measure of water clarity, in July and August decreased from 5.7 to 2.4 meters (m) in July and 5.1 to 2.8 m in August from 2018 to 2021 respectively.

This is probably due to an increase in microscopic algae growth; which is the end result of a chain of events influenced by urban run-off of nutrients, salts and sediments, climate change and invasive species.

Average chloride (Cl) level was 150 mg/L, already exceeding the Canadian Water Quality Guideline to protect aquatic life, and has remained stable from 2018-2021. In the same period, sodium (Na) has been increasing (up to ~100 mg/L). Both Na and Cl levels are associated with road/ rock salt (NaCl), used for winter road, commercial parking lot and residential driveway winter maintenance, entering the lake.

Surface phosphorus (P) levels ranged from 12.3-19.5 ug/L; still hovering close to the Provincial Water Quality Objective threshold.

But we can make a difference!


Review your own practices;

  • Use your shovel/ snowblower and traction aids first on your winter driveway. Avoid products that are pure ‘rock salt’, sodium chloride or NaCl. Rock salt‘s lowest effective working temperature is only -7°C; even though most packages of the product state ‘lowest effective temperature’ of -15°C. It also corrodes your concrete and car bodies, stains your shoes and carpets…and stresses the lake!!

  • Reserve the use of other chloride-containing ice melts for spots or conditions where melting ice for safety concerns is really needed. Refer to GSWA’s Decision Aid to Common Residential Ice Melts and Traction Aids

  • Use fertilizers that are phosphorus free…that means no “P”; or “0 in the middle”, as outlined in the City of Greater Sudbury’s By-Law 2012-58

  • Stay involved and encourage your neighbours to join us.



As our group grows, we can all contribute in some way; some being more fun than others! Meet one of our Citizen Scientists, Bruce Holson…Secchi Depth sampler extraordinaire!


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