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Great Lakes Precipitation Network

Sampling Station at Burnt Island | © EC - Photo: Bruce HarrisonA 1969 International Joint Commission Report stated that very little information existed about the contribution of atmospheric inputs to the chemical budgets of Lake Ontario and Lake Erie. The Great Lakes Precipitation Network (GLPN) was thus initiated by Environment Canada, with a few “bulk” precipitation collectors along the shores of Lake Ontario. Over the next two years, other stations were established on lakes Erie, Huron and Superior. With the signing of the Great Lakes Water Quality Agreement between Canada and the U.S. in 1972, there was a greater concern for the present and future water quality of all of the Great Lakes. In response, the network expanded and evolved to monitor the long-term status and trends of nutrients throughout the Great Lakes Basin. For the next several years, data from bulk precipitation collected by the GLPN revealed that rain and snow were important contributors of nutrients to these lakes. In 1979, the network changed to wet-only precipitation collectors to eliminate contamination and evaporation in the measurement of the concentrations of trace metals, nutrients and major ions. A trace organic precipitation network was initiated in 1985. In 1994, the two networks were amalgamated to form a nine station network. The network contributes to the Binational Integrated Atmospheric Deposition Network (IADN).

IADN was created under the Canada-U.S. Great Lakes Water Quality Agreement. Annex 15 of the revised 1987 Canada-U.S. Great Lakes Water Agreement states that the parties shall conduct research, surveillance and monitoring and implement pollution control measures for the purpose of reducing atmospheric deposition of toxic substances to the Great Lakes Basin ecosystem. The United States Environmental Protection Agency and Environment Canada each implement an integrated and coordinated air and precipitation monitoring program at selected sites. The main goal of this network is to determine, with a specified degree of confidence, the atmospheric loadings and trends (both spatial and temporal) of priority toxic chemicals to the Great Lakes and its basin. It is also the network’s responsibility to identify “emerging problems” in atmospheric pollution in the Great Lakes Basin.

Presently the GLPN consists of eight active sampling sites. Two of the sites are IADN master stations: Burnt Island and Point Petre. The other six are referred to as satellite stations: Sibley, St. Clair, Burlington, University of Toronto, Point Pelee, and Rock Point.

Map of Great Lakes Precipitation Network sample sites in the Great Lakes Basin

Map of Great Lakes Precipitation Network

The sites are generally paired as suburban/rural and are generally located at opposite ends of the lake to allow for more accurate loadings estimates.

The general requirements are that a sampling site should not be affected by local sources; it requires 120V electric power, it should have a dedicated operator and it should be easily accessible year round. The sites were chosen for their proximity to the lakes and are deemed to be regionally representative of each lake basin.

Sibley is located within Sleeping Giant Provincial Park on the north shore of Lake Superior. Burnt Island is located on the north shore of Manitoulin Island on Lake Huron. These sites are far removed from industrial and urban centres. The St. Clair site is located at the St. Clair Wild Life Research centre on the east shore of Lake St. Clair. The two stations on Lake Erie are located at Point Pelee and Rock Point. Point Pelee is located at the southwestern end of Lake Erie in Pelee National Park on the mainland. Rock Point is also a provincial park on the northeastern shore of Lake Erie. St. Clair and Point Pelee are both downwind of the major industrial centres and heavily industrialized regions of the Detroit/Windsor and Sarnia areas. The Burlington and Point Petre sites are both located on Lake Ontario. Burlington is located at the western end of the lake, halfway up the Niagara escarpment, within sight of Toronto and within the influence of the steel mills in Hamilton. Point Petre is located at the northeastern end of the lake in a rural location. The sampling station at the University of Toronto is the Canadian urban location for IADN.

Inorganic precipitation sampler at Burlington siteAt each sampling site, a wet-only precipitation collector is employed to collect wet/frozen precipitation. There are two types of samplers. The MIC type-A sampler collects precipitation in a pre-cleaned polyethylene bucket. At the end of each calendar month, the sample is emptied into a clean polyethylene bottle and the bucket is replaced with a clean one. The sample and the bucket are sent to the Water Quality Monitoring and Surveillance (WQMS) laboratory for processing and cleaning. At the laboratory, the sample volume is measured, subdivided, (preserved, if necessary) and submitted to the analytical laboratory for nutrient, major ion and metal analyses. The bottle and the bucket are cleaned and sent back to the station for sample collection.

Organic precipitation sampler at the St. Clair siteThe MIC type-B sampler is equipped with a stainless steel square funnel. An insulated cabin under the funnel houses the 4-L amber glass sampling bottles required for organic analysis. The temperature of the cabinet is maintained above freezing during the winter months by a thermostatically controlled electric heater. Each sample bottle is prefilled with 250 mL of high purity grade methylene chloride to preserve the sample throughout the collection and storage period. Bottles are changed when they are full or otherwise at the end of the one-month collection period. Samples are kept at 4oC until analyzed. The list of persistent chemical contaminants being monitored include: organochlorine pesticides, polyaromatic hydrocarbons, PCBs, flame retardants, and PFOS. All samples, both organic and inorganic, are analyzed at the National Laboratory for Environmental Testing (NLET) at the Canada Centre for Inland Waters in Burlington, Ontario.

List of analytes measured at different locations.  PCBs: polychlorinated biphenyls; OC: organochlorine pesticides; PAH: polycyclic aromatic hydrocarbons; FR: flame retardants; TM: trace metals; MI: major ions; Nuts: nutrients
StationStation TypeSampler TypeAnalytes Measured
Point PetreIADN Masterprecipitation collector type-A
precipitation collector type-B
Burnt IslandIADN Masterprecipitation collector type-A
precipitation collector type-B
OC, FR, PFOS, TM, MI, Nuts
Sibley Provincial ParkSatelliteprecipitation collector type-A
precipitation collector type-B
OC, FR, PFOS, TM, MI, Nuts
BurlingtonSatelliteprecipitation collector type-A
precipitation collector type-B
OC, PAH, FR, TM, MI, Nuts
St. ClairSatelliteprecipitation collector type-A
precipitation collector type-B
OC, FR, TM, MI, Nuts
TorontoSatellite (IADN urban)precipitation collector type-A
precipitation collector type-B
Point PeleeSatelliteprecipitation collector type-ATM, MI, Nuts
Rock PointSatelliteprecipitation collector type-ATM, MI, Nuts

The Great Lakes Precipitation Network is operated out of the Ontario office of Water Quality Monitoring and Surveillance (WQMS). Here project leaders, technical and field staff coordinate the maintenance of sampling equipment and timely sample collection and analysis. Although there have been numerous changes in sampling sites, sampling equipment, sampling protocol and analytical methods, the GLPN holds a unique and extensive data set on chemical contaminants in precipitation for the Canadian Great Lakes Basin.

The Great Lakes Precipitation Network (GLPN) Inorganic Methods Measured

  • Metals, monthly integrated samples, unfiltered. Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V, Zn
  • Major Ions, monthly integrated samples, unfiltered. Ca, Mg, Na, K
  • Chloride & Sulfate, monthly integrated samples, unfiltered. Cl, SO4
  • Nutrients, montlhly integrated samples, unfiltered. NO3, NO2, NH3, Total Kjeldahl N, Total P
  • Physicals, monthly integrated samples, unfiltered. pH, Conductivity

For more information about the program, sampling methods, or to request data please send your inquiries to:

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