Lake Partner Program


Program Overview

The Lake Partner Program is Ontario’s volunteer-based, water-quality monitoring program. Since 2002, the Ontario Ministry of the Environment and Climate Change has coordinated this lake monitoring program from the Dorset Environmental Science Centre (DESC), in partnership with the Federation of Ontario Cottagers' Associations. Each year, more than 600 volunteers monitor total phosphorus and water clarity in almost 550 inland lakes at over 800 sampling locations. Volunteers collect lake water samples and return them, postage paid, to DESC. Total phosphorus and calcium analyses are performed in the DESC Water Chemistry Laboratory. The resulting data are used by members of the public, partner agencies, government and academic researchers and private consultants to assess and report on water quality in lakes across Ontario. This total phosphorus, calcium and water clarity data are published each January on the provincial Lake Partner Program webpage.


Program Details

Lake Partner Program volunteers collect total phosphorus samples and make monthly water clarity observations on their lakes during the summer months. By measuring total phosphorus and water clarity, it is possible to detect long-term changes in the water quality of individual lakes that may be due to impacts of shoreline development, climate change and other stresses. Phosphorus is measured because it is the element that limits algal growth in the majority of Ontario lakes. Generally, more phosphorus means more algal growth.

Each year, the volunteer members of the Lake Partner Program are sent kits that contain the materials necessary to conduct water clarity measurements and take water samples. The samples are returned, postage paid, to DESC for analysis. For more information or to find out how you can become a volunteer Lake Steward with the Lake Partner Program, please visit the Lake Partner Program webpage, fill out this online registration form, or contact the Lake Partner Program directly.

The number of total phosphorus samples taken each year by volunteers depends on whether or not the lake is on the Canadian Shield. For lakes located “on” the Canadian Shield, total phosphorus samples are collected in May (during the spring-turnover period) and Secchi disc water clarity measurements are taken at least once every two weeks throughout the summer. For lakes located “off” the Canadian Shield, one sample is collected each month from May to October and water clarity readings are made at least once every two weeks. For more information, you can download our volunteer sampling instructions


Resources and Publications






Sampling Instructions


Understanding Your Data


View Lake Partner Program Data



Contact Information

Anna DeSellas

Coordinator, Lake Partner Program
email: lakepartner@ontario.caDorset Environmental Science Centre
Box 39, 1026 Bellwood Acres Road
Dorset, ON, P0A 1E0Phone:1-800-470-8322; 705-766-1294 (outside Ontario)Fax:705-766-2254