Fish mercury concentrations in reservoirs can increase several times above background levels, peak 5-15 years after flooding, and take 2-3 decades to recover to levels within the natural range for lakes. Some reservoirs experience greater increases and take longer to recover than others. Mr. Harris co-developed a process-based model predicting fish methylmercury concentrations in newly flooded reservoirs (See below – Harris et al., 2009). The model, funded by Manitoba Hydro, was calibrated against data from whole-ecosystem reservoir experiments at the Experimental Lakes Area (ELA) in Ontario, Canada (FLUDEX, ELARP). It predicts peak fish mercury levels and the timing of the response to flooding. The model pays special attention to flood zone characteristics because decomposition after flooding is a key driver for increases in methylmercury levels in new reservoirs.
Mr. Harris also co-developed a simple model to predict peak mercury concentrations in fish in reservoirs, based only on the flooded area, total reservoir area and mean annual flow (See below – Harris et al., 2008; Harris and Beals 2009). The model has been calibrated separately for northern pike and walleye using historical observations from reservoirs in Quebec, Manitoba, and Ontario. The approach is currently being used for proposed reservoirs in Labrador and Ontario.
References:
Harris et al., 2009
Harris, R.C., D. Hutchinson, and D. Beals. (2009) Predicting Mercury Cycling and Bioaccumulation in Reservoirs: Development and Application of the RESMERC Simulation Model. Final Report, April 2009. Prepared for Manitoba Hydro
Harris et al., 2008
Harris, R.C, D. Hutchinson and AMEC (2009) Lower Churchill Hydroelectric Generation Project
Environmental Baseline Report: Assessment of the Potential for Increased Mercury Concentrations. March 4, 2008
Harris and Beals 2009
Harris, R.C. and D. Beals. (2009) Assessing the Potential for Increased Fish Mercury Concentrations Associated with the Proposed Gitchi Animki Hydroelectric Project – Draft Final Report (2009)Prepared for Regional Power Inc., Mississauga, Ontario, August 2009
