60th Anniversary of the Provincial Water Quality Monitoring Network

June 10th, 2024 marks the 60th anniversary of the Ministry of the Environment, Conservation and Parks (MECP)’s Provincial Water Quality Monitoring Network (PWQMN). The PWQMN measures water quality in rivers and streams across Ontario to track changes in water quality over time.

Since 1964, Ontario’s Conservation Authorities, including the Upper Thames Conservation Authority (UTRCA), have worked collaboratively with PWQMN partners to collect monthly water samples at over 400 locations across Ontario. In the Upper Thames River watershed, there are 24 active water quality stations that are sampled from March through October, or April through November, depending on the timing of spring melt. Nine of the stations are sampled eight times a year and the other 15 are sampled four times a year.    

Over the years, site locations have been added, removed (due to lack of funding), and relocated near outlets of Upper Thames River subwatersheds to better reflect the UTRCA’s approach to monitoring, reporting, and program implementation. In recent years, winter samples have been collected at five sites from December to March.

Winter sampling has allowed PWQMN to collect water samples throughout all four seasons at these stations. This is important for nutrient movement in river systems because of changes in flow from rain and snow during winter. 

Interesting Facts: 

• UTRCA started monitoring for PWQMN in 1964 at nine sampling stations 
• Sites that have been monitored for the full 60 years include: 
  • Cedar Creek – Cedar Creek Subwatershed 
  • South Thames River at Woodstock – North Woodstock Subwatershed 
  • Dingman Creek – Dingman Subwatershed 
• UTRCA has collected over 11,000 water samples for PWQMN since 1964 
• During sampling season, staff travel just over 300 kms to sample 24 stations 
• In 2023, 147 surface water samples were collected for analysis 
• Parameters that are being analysed include:  
  • General Chemistry: Chloride, Suspended Solids, Conductivity, pH, Alkalinity, Nitrogen, Hardness, Phosphorus, Carbon, Silicon 
  • Metals: Aluminium, Barium, Beryllium, Bismuth, Calcium, Cadmium, Cobalt, Chromium, Copper, Iron, Potassium, Lithium, Magnesium, Manganese, Molybdenum, Silver, Sodium, Nickel, Lead, Tin, Strontium, Titanium, Uranium, Vanadium, Zinc, Zirconium

In addition to PWQMN, the UTRCA collects surface water samples as part of the Environmental Targets: Strategic Plan June 2016. The Environmental Targets Monitoring (ETM) has supplemented water quality monitoring in PWQMN by increasing the temporal and spatial resolution of the data. This is achieved by sampling at the 15 PWQMN stations that are only sampled four times a year to ensure a complete eight-month dataset, adding three long-term stations, ensuring all 28 subwatersheds are sampled for eight months, and sampling for bacteria at all stations after bacteria was dropped from the PWQMN program.