The Trent-Severn Watershed (Source: Parks Canada Water Levels Website) - PowerPoint PPT Presentation

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review of 2019 summer weather and water n.
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The Trent-Severn Watershed (Source: Parks Canada Water Levels Website)

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  1. Review of 2019 Summer Weather and Water Management Across the TSW Reservoirs with Focus on Mississagua Chain of Lakes CCRAI Meeting – August 17, 2019 Ted Spence CCRAI Board member; Chair CEWF and Professor Emeritus in Environmental Studies York U. 1

  2. The Trent-Severn Watershed(Source: Parks Canada Water Levels Website)

  3. Reservoir & Flow-Through (RAFT) Lakes • In the “Haliburton Sector” (Haliburton County and northern Peterborough County) there are 35 reservoirs – • 17 in the Gull River system (23,669 ha-m storage), • 13 in the Burnt River System (7,609 ha-m storage), and • 5 in the Central Lakes area (12,388 ha-m storage) including the Mississagua chain of lakes, Anstruther , Eels, Jacks and Crystal lakes. • The reservoir seasonal water level changes of up to 10 feet (3.4 m) combined with severe flow constraints at some points downstream (e.g. Minden, Peterborough) • There are also challenges to maintaining navigable water levels on connecting rivers and flow-through lakes and minimum flows and levels for fisheries management.

  4. Trent River System Flow Chart(Source: Parks Canada 2013)

  5. Key Water-Flow & -Level Constraints • TSW priorities public safety (flood management and water supply) and canal navigation; • Minimum flow at Peterborough for water supply and sewage treatment; • Maintaining the Canal Regulations draught limits is understood to govern the drawdown from the reservoirs; • While aiming to maintain reservoir levels within historic norms

  6. Recent Experience • In last three summers reservoir levels have been good for us but TSW has had to continuously adjust to extreme weather conditions. • 2016 extreme rain and flooding in March, record setting drought May to 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 followed by drought conditions and spotty rainfall through to end of July and a Very wet August. • Now in 2019 extreme snowpack and very wet spring then more than 6 weeks of drought with only local rainfall events.

  7. 2016 Mississagua Lake Water Levels

  8. Mississagua Levels 2017

  9. 2018 Mississagua Lake Water Levels

  10. 2019 Spring/Summer Precipitation Haliburton

  11. 2019 Mississagua Lakes Water Management Experience • Dam remained at winter setting throughout March and April. • Higher than normal snowpack combined with April rainfall resulted in exceptional reservoir filling to above full with logs still out. • Same conditions applied throughout Trent Basin - too much water and storage full. Canal opening delayed because of high water and flows. • Strategy at Mississagua through May and into June was to pass as much water as possible while reacting to rainfall to avoid flooding. High river flows and active log operations. • In mid June some logs still out as they worked to manage level back down to normal range. • From early July - Drought conditions and minimum flows on Canal with draw from reservoirs.

  12. 2019 Mississagua Lake Levels

  13. 2019 Mississagua Lake Levels Table

  14. Drawdown Forecast August 13

  15. 2019 View at Mid-August • With climate change the year to year variability is increasing and we are seeing more extreme events including drought periods in 2016, 2018 and 2019. • In 2019, even with 3.5 times the normal snowpack at end of March and 180% of normal rain in April the flood levels were less than in 2017. • Strategy at Mississagua through May and into June was to pass as much water as possible while reacting to rainfall to avoid flooding. Then hold above normal level. • From early July - Drought conditions and minimum flows on Canal with draw from reservoirs. • We need significant rainfall basin wide NOW to avoid the risk of extreme drawdown.

  16. CEWF.CA