Water quality monitoring data is collected in priority tributaries as part of binational efforts under Aneex 4 of the Great Lakes Water Quality Agreement (GLWQA) to estimate nutrient loading to the waters of the Great Lakes. At present, the focus is primarily tributaries of Lake Erie, the smallest, shallowest of the Great Lakes, and most susceptible to algal blooms. Tributaries may be added or removed from active monitoring dependent upon recommendation of binational working groups under the GLWQA. These data are used to track and report on progress towards meeting nutrient loading targets established for Lake Erie. The data also contribute to our understanding of the factors that affect tributary and nearshore and offshore water quality, algae growth and overall ecosystem health.
Measurement Technique: Sample collection for tributary nutrient load monitoring and assessment is conducted year round in several priority watersheds in the Lake Erie basin. At each monitoring station, water samples are collected by an automated sampler, which is located within a fixed installation at, or near, a Water Survey of Canada (WSC) hydrometric station. Water samples are collected on a minimum bi-weekly frequency. In addition, water samples are taken during wet weather induced flow events, identified from WSC hydrographs, over the two-week period to best capture the full variation of stream flows at each station. Samples are drawn directly from submerged polyethylene intake lines via submersible pumps, then collected into pre-cleaned polyethylene bags and are refrigerated at all times. Samples are analyzed for nutrients and major ions by the National Laboratory for Environmental Testing (NLET) and follow all accredited QA/QC laboratory procedures.