WLTF Report to MLA Members Issue 2017-12

May 17th – 12:00pm]: …… Going into the Victoria Day long weekend, MNRF has, as of Tuesday afternoon, removed all Food Watch / Warning notifications for our watershed.  Water levels are approaching normal for this time of year.  Lake Muskoka could reach summer target by the weekend.  Lakes Rosseau and Joseph could reach normal Spring levels by the weekend. Drawdown in Bala Bay suggests that Bala Reach water levels will recede below flood level by week’s end.  Please appreciate these are educated guesses; are very rough, and for general guidance only.  Events such as the predicted 25mm of rain in the watershed on Sunday will have a negative impact on our water levels.  As freshet is now past, this will be the last weekly newsletter for this year.

Watch out for floating debris if travelling by boat.

June 11th Water Level Seminar - Come join us and meet with speaker Chris Cragg, Muskoka Lakes Association’s Chair of the Water Quality and Environment Committee and member of the Water Level Task Force, to learn about water level management in Muskoka.                               Click here for details.

EDITOR’s NOTE:   A Big Thank-You to the WLTF Team!  These newsletters would not have been possible without the dedicated volunteers whose diligent efforts over the past year (many weekly meetings, data analysis and numerous political meetings at various levels of government) have kept you informed and are making a difference.  Further irregular updates as may be useful, will be published ad hoc.

What does this mean to you?

The level of each property owner’s docks relative to lake level is unique to individual circumstances. The MLA strongly encourages property owners to relate their docks/boathouses to the nearest Environment Canada water level gauge as outlined in previous newsletters.

How we got here:

See earlier newsletters for this winter’s water level history.

Lake Muskoka Update:

Figure 1 below shows Lake Muskoka water levels are dropping at a steady 4 cm [1.6”] per day, have regained the previous low level of May 1st and are continuing to drop. Projecting this rate to the end of the week yields a level of 9.55m by the weekend.  This water elevation is what the watershed management plan calls for at start of summer.  Most docks should now be above water.

Figure 1: LAKE MUSKOKA – 2017 WATER LEVELS [meters above gauge 02EB018]
For reference, Normal Summer levels: 9.35m to 9.65m; Flood Level 10.05m on above figure.

Lakes Rosseau and Joseph Update:

Water levels on Lakes Rosseau and Joseph have also been receding at a steady 1.2 cm [1/2”] per day.  Faster drawdown is not possible due to flow restricting narrows upstream of the Port Carling small locks and also at the Indian River’s entrance to Mirror Lake.  Projecting this drawdown rate forward indicates these lakes could be at an elevation of 9.11 m by the week end. This would regain the year’s previous low level achieved on April 28th which was top of Spring normal. Many, but not all docks, should be above water by the week end.  Progress towards summer level could continue into the next week, barring high rainfall.  Lower elevation docks may not be above water until after the long weekend.

Figure 3: LAKE ROSSEAU/JOSEPH WATER LEVELS 2017 [above gauge 02EB020]

For reference, Normal Summer levels 8.88m to 9.03m; Flood Level 9.28m ; Top NOZ = 9.13 m April 1 to May 20th

Bala Reach/ Moon River Update:

Since last week, flow has decreased from 330 cms to about 290 cms, just above the flood warning level of 280 cms.  This flow amount is expected to decrease over the next few days as levels in Lake Muskoka decrease to a level below the Flood Warning level.  Water levels are still expected to be high and well above the winter normal range.  Further drawdown and perhaps some logging in at the Bala Dams is still needed to reach summer normal levels.  Members are advised to exercize caution if boating due to   ongoing high water and high flows.

Ice Damage

Although the ice is now out, members are advised that damage did occur over the winter due to ice expansion. Please see earlier communications for details.


The water levels for Lakes Muskoka, Rosseau are trending towards summer levels following a two tiered freshet.  Lakes that do not reach summer levels by the long weekend should get there by the end of May.  The MLA wishes you a summer of safe and enjoyable boating.