2018 Mississagua Lake Levels to June 20, 2018

Presentation to the Cavendish Community Ratepayers’ Association Inc. – CCRAI

June 23, 2018Ted Spence – CEWF Chair, CCRAI Board member, and Professor Emeritus in Environmental Studies, York U

cewf.ca

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Presentation Outline

• Overview of Trent-Severn Waterway System

• Review of recent years’ experience with Lake

levels

• Review of 2018 weather patterns January to

June

• Mississagua Lake levels 2018

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

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 (7609 ha-m storage), and

– 5 in the Central Lakes area (12,388 ha-m storage) including the Mississauga 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.

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

Summary of Climate Change Implications for Water Management

Winter and Spring• 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 adjust logs in winter to reduce flood risk, to capture winter runoff, and to fill reservoirs while ice on lakes.

• 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 and 2017 may lead to overfilled reservoirs and possible flooding some years with ice still in place as in recent experience.

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Recent experience

• 2013 (mid-April) and 2017 (early May) extreme spring rainfall with flooding especially in Gull River.

• 2014 and 2015 extreme cold leading to very low levels by February.

• 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.

Comparison of Three Recent High water Events

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Year Event datesTotal Ppte

mm Notes

2013 April 15 to 19 5 days

61 mm Rain on snow and some frozen ground. April Ppte 13mm vs 75 mm Normal (182% of Normal). Event concentrated in Haliburton.

2016 March 24 to 31 8 days

97 mm March rainfall 171 mm vs normal 72 mm with 97 mm in last 8 days of month. Basin saturated. Late Ice out with Ice still on lakes. Event Concentrated in Haliburton.

2017 April 30 to May 6 7 days

128.4 mm April Ppte 144 mm vs 75 mm normal 192% normal. Basin saturated. Rainfall event over entire Trent basin.

2017 Spring-Summer Rains

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2017 Spring Precipitation Haliburton

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Spring Precipitation Summary for Haliburton

MonthPpte Total mm

Rain mms

Snow cms

Normal Monthly Total mms

Actual as % of Normal

2017 April 144 131 13 75 192%2017 May 190.6 189.6 1 93 205%2017 June 148.9 148.8 0 81 184%2017 July 96 96 0 90 106%

Mississagua Levels 2017

2018 TSW Water Management Strategy

• Objective until early May was to minimize flood risk particularly above Minden and Peterborough

• Weather patterns were variable and the historical average was not the focus in decision making.

• Daily water management decisions were based on data of water levels, river flows, snowpack water content, and soil conditions, as well as the latest precipitation forecasts.

• In mid-May the objective shifted to filling reservoirs and the canal lakes taking account of levels and forecast precipitation.

2018 Winter/SpringPrecipitation Haliburton

2018 Month

PpteTotal mm

Rain mm

Snow cms

Normal Monthly Total mms

Actual as % of Normal

Month End Snow on Grd cms Notes

2018 Jan 113.4 53.6 59.8 100 113% 6

2 rain events 20mm+, Norm snow on grd is 32 cm

2018 Feb 97 51.8 45.2 73 133% 9

40mm of rain on 19th and 20th, Norm snow on grd is 42 cms

2018 March 40 16.6 23.4 75 53% 0

No Significant ppte events, Norm snw on grd is 16

2018 April 128 62.4 66.4 75 171% 0

Apr 12 to 16 22 mm rain 34 cms snow, 25 mm rain on 25

2018 May 79.4 79.4 0 93 85% 0Dry month with 25.8 cms rain on the 31st

2018 June to 13th 20.6 20.6 0 81 25% 0 To 13th

Haliburton Precipitation from Oct 2017 to May 2018

Source: Parks Canada

May 7 2018 14 Day Forecast

2018 Mississagua Lake Levels to June 18

Mississagua Lake Table View

2018 Anstruther Lake Levels to June 13

Summary of 2018 Levels and Flows• Winter rains and runoff and below average lake levels

to manage flood risk.

• Extreme rain/ice and snow event in mid-April.

• Rapid runoff and lake level rise end of April with significant rain in long range forecast, and ice on lakes.

• Release of lake water April 28 with river flooding and damage.

• Refilling lakes through May (dry month) with dam closed and very low river flow.

• Increased river flow over May holiday weekend.

• Minimum river flow in June as lakes fill slowly.

New TSW Website Connect through CEWF.ca

New TSW Website

TSW Website Graph View

Mississagua Lake Table View

Cewf.caLinks to TSW and CEWF News, TSW Water

Levels, and Water Level Forecasts

Questions

and

Discussion