On June 10, 1964 the first water sample of the Provincial Water Quality Monitoring Network (PWQMN) was collected at a site on the North Maitland River. Since then Maitland Conservation staff have collected thousands of samples in the Maitland River watershed, and thousands more have been collected by PWQMP partners across the province.

The PWQMN is a collaboration between Conservation Authorities and the Ministry of the Environment, Parks and Conservation. The purpose of collecting and analysing the samples is to measure water quality in rivers and streams to track changes in water quality over time. There are over 400 sampling sites across Ontario.

Although the original Harriston location is no longer a collection site, Maitland Conservation staff are currently sampling at 12 other sites. Three of these sites are sampled monthly throughout the year and the rest are sampled from April to November.

The samples are analysed for a wide range of parameters including Chloride, suspended solids and Phosphorous and the results are used to identify water quality trends. For example, in the Maitland River watershed Chloride levels (salt) have been rising, particularly in urban areas. In addition, data from the PWQMN is used in a variety of assessment reports including MECP’s State of the Great Lakes reports, Environment and Climate Change Canada’s Environmental Sustainability Indicators and by NGOs including the World Wildlife Fund.