Climate Change – TSW and the Reservoir Lakes

Presentation to Environment Haliburton Enviro-Cafe

Oct. 11, 2016 by Ted Spence – CEWF Chair,

and Professor Emeritus in Environmental Studies York U.

On October 11th our CEWF Chair, Ted Spence, spoke to the Environment Haliburton group on the topic of Climate Change, the Trent-Severn Waterway and the Reservoir Lakes. In addition to reviewing information previously presented to our CEWF annual meeting and posted on this website on September 14, 2016, Ted discussed several recent reports on climate change projections covering the Trent Watershed. He related these projections to variations in weather patterns and water levels in recent years and discussed the implications of the recent experience and longer range projections for shoreline property owners. A summary of the key conclusions follows. For a full set of presentation slides – click here.

Recent Reports on Climate Change Projections for Central Ontario

The presentation summarized the findings of three recent reports which are particularly relevant to the Trent River watershed.

These reports are the AECOM TSW Water Management Study from 2011, two reports from Kawartha Conservation dated 2015 and 2016, and a 2016 study from the Muskoka Watershed Council. In addition a very recent report from FOCA and the MNRF was also reviewed.

The Climate Change discussion is outlined in slides 44 to 63 in the attached presentation.

The reports are consistent in predicting warmer temperatures especially in winter and increased precipitation in winter including significant rainfall events. These conditions are projected to result in more runoff in winter with a risk of winter flooding with ice on the lakes, an earlier spring freshet and the need to replace logs in winter or earlier in spring to capture the runoff to fill the reservoirs. The “new normal” will be a higher risk of winter flooding, earlier spring runoff with a lower peak but possibly with ice on lakes. Under these conditions extreme spring rainfall events are likely to result in overfull reservoirs with the risk of downstream flooding as in 2013 and 2016.

The projections for summer are for warmer temperatures and more frequent extreme events including periods of drought and more of the precipitation concentrated in major storm events. The higher temperatures will cause more evaporation from the lakes including the large Kawartha Lakes and the demand for reservoir water may be greater. In drought conditions minimum flow constraints will drawdown all lakes in the Gull and Burnt River systems as experienced in the Burnt River reservoirs in 2016. Extreme storm events may result in sudden lake level rises and river flooding.