2019 WATER LEVELS - IN REVIEW
Lots of snow and extreme spring rain followed by drought in 2019!
Kushog Lake was way below average until mid-April when the level rose 1.6 m (over 5’) in 3 weeks – very close to the maximum recorded level. It remained close to the maximum until mid-August after which it remained above average for the rest of the year.
Recent Experience in the Gull River Watershed
• In last three summers, reservoir levels have been good for us, but TSW has had to continuously adjust to and manage for extreme weather conditions each year. Often this has included water conservation with minimum flows downstream on Otonabee and Trent Rivers.
• 2016 extreme rain and flooding in last 8 days of March (rainfall 171 mm vs normal of 72 mm – 233%); late ice out with ice still on lakes; record setting drought May until mid August.
• 2017 early snowmelt, extreme rain early May, flooding and continuing excess rainfall. Higher than normal levels all summer and into fall.
• 2018 extreme rain/snow/ice in April (144 mm vs normal of 75 mm), followed by drought conditions and spotty rainfall through to end of July, with slow filling of some reservoirs and drawdown beginning in early July. Very wet August.
• 2019 End of March 54 cms snowpack vs normal of 16 cms. April rainfall 142 mm vs normal of 75 mm onto snow and frozen ground.
Summary of Climate Change Implications for Water Management
Winter and Spring 2019
• Warmer winter temperatures and significant increase in winter precipitation including significant rain events will lead to more runoff in winter and early spring, and the need to replace logs in winter to capture winter runoff to fill reservoirs.
• The “new normal” will be higher risk of winter flooding, earlier spring runoff with lower peak but possibly with ice on lakes.
• BUT extreme spring rain events like 2013, 2016,2017 2018 and 2019 may lead to overfilled reservoirs and possible flooding with ice still in place as in recent experience.
• Most immediate trend is more variability and extreme events including rainfall and drought conditions. Every year is different!
Summer and Fall
• More of our rainfall will be in more frequent major storm events. More frequent drought periods like in 2016 and 2019 possible.
• With warmer summers like 2019, higher temperatures will cause more evaporation from the large Kawartha Lakes and large reservoirs, and the demand for reservoir water may be greater.
• In prolonged drought conditions, minimum flow constraints may drawdown all lakes in the Gull and Burnt systems as experienced on the Burnt in July 2016.
In Recent Years TSW has taken Substantial Action To Make Water Management More Data and Analysis Driven
• Added 5 real-time snow gauges to augment snow survey readings
• Operate over 20 rain gauges with daily reporting • Installed automatic level recorders on almost all reservoirs
• Monitor and analyse inflow/outflow water balances to understand storage
• Adopted a precipitation/runoff model to provide inflows to lakes based on forecast precipitation and snowmelt, and a routing model to forecast flows and water levels throughout the system
• On a daily basis data analysis leads to decisions on operations across the watershed.