Muskoka Water Levels

DON’S DIALOGUE  –  WATER  LEVELS  IN  MUSKOKA

First, let me preface this article by saying, these are my personal comments from observations and data I have collected. They are not intended to be a complete scientific analysis of water levels on the Muskoka River Watershed by a professional hydrologist.   Also my observations are based on Bracebridge and Lake Muskoka data only, which does not consider the significant variability that exists in our watershed.

In the Spring of 2013 and 2016 Lakes Rosseau, Joseph and Muskoka, as well as many others in the Muskoka River Watershed experienced unusually high water levels during the Spring Freshet.   This is certainly not a new phenomenon, but it does appear to be more frequent and severe than we normally experience.   I am going to limit my comments to some of the events that I observed from Sept 2015 to April 2016.

Physical Factors:

Many of our residents believe that the 44 level control devices on the Muskoka River Watershed were constructed to control flooding.   They were not.   These devices (dams and weirs) were originally constructed in many cases over a hundred years ago, as level control devices to facilitate navigation and logging activities. They are also intended to assist in the operation of many small run of the river hydro plants, fish spawning and riparian water rights for residents.  These dams collectively contain over 500 logs that are manually inserted and removed to adjust water levels.  An adjustment in Algonquin Park will take 2 to 3 days to work through the system.  The dams are not flood control devices.   However, there is some inherent ability to selectively hold back or release more water, but this ability is very limited.   The levees of the Mississippi, which did not help New Orleans during Hurricane Katrina, the dykes of Holland and the Red River diversion channels around Winnipeg are flood control devices.   Certainly we all know that despite the best efforts of engineers and operators, flooding does occur even if flood control devices are in place.

Our climate has always been in a state of change but today we are seeing this change occurring more rapidly.   These changes are forecast on average, to produce warmer dryer summers and warmer wetter winters during the twenty first century.     Climate models tell us we can expect more winter precipitation in the form of rain and less as snow.  We can also expect more extreme and variable weather i.e. more severe rainfall and hotter dryer summer temperatures over longer periods.  The cold winters like 2014 -15 will certainly occur but with less regularity than in the past.

The Muskoka River Watershed drains over 5,000 square kilometers of land and falls about 350 metres from Algonquin Park to Georgian Bay.   The precipitation varies significantly throughout the watershed, as does the snow pack and melt rate due to weather variability on any given day or hour.    Another major variable is   composition of soils, water saturation levels and steepness of slopes.  As I am sure you can appreciate, dry sandy soils will absorb more rainfall than those that are frozen, rocky or very steep.

The last major contributor to water level fluctuation is the physical ability of water to exit the system due to “choke points”.     Almost all the water must exit via the Falls in Bala and the Moon River.   The narrow openings into Bala Bay and at the Moon River Chutes, physically restrict the time it takes for water to exit the system without significantly raising the water levels.

In summary the major influences on water levels are manually operated dams – (not flood control devices), climate change (more severe weather events, hotter, dryer summers and wetter warmer winters), soil variability, precipitation variability and choke points.

Fall 2015

During September I had people contact me complaining that the water levels in the big three Muskoka Lakes were too low and their boats were literally sitting at the bottom of their boathouse slip.   However, by the end of November the same people were upset that the water levels were so high that their boathouses were being flooded.

Based on my observations, the Bracebridge weather records and the Hydrometric Lake Data for Beaumaris, the complaints I received are legitimate.   The water levels at the end of September reached the bottom of the Muskoka River Water Management Plan (MRWMP) target operating range.  By the end of November they were at the other extreme.  Before assigning blame or responsibility to the Township of Muskoka Lakes (TML) or the Ministry of Natural Resources and Forestry (MNRF) for human failings to operate the system properly, I suggest a closer examination of the major natural contributors i.e. precipitation and temperature need to be reviewed.

September 2015 was one of the warmest Septembers on record in Muskoka. Only 65 mm of rain fell in Bracebridge which is well below normal and over half of that total fell on September 8th and 9.   Higher temperatures caused more evaporation and combined with less rainfall, we saw lake levels drop.

During October we received 115 mm of rainfall, significantly above average with 44 mm falling during the last 4 days of October. I might add that temperatures remained unusually warm well into November.   So why can’t we get rid of this water in early November? I am speculating, but this is a critical time for lake trout spawning.   Dropping the lake levels would expose lake trout eggs to the air greatly increasing mortality rates.  Also the last 10 days of November were very cold, well below freezing reducing evaporation and the normal runoff.

 

Winter & Spring Water Levels

During December and January water levels trended downwards to the mean level of the MRWMP target operating range. Ice-over of Lake Muskoka occurred in late January 2016 verses just before Christmas 2014.    Just after the ice formed in late January a large fall of snow insulated the ice and inhibited the formation of the usual 12 to 24 inches of ice in the big lakes.   I might add that many of the smaller bays were frozen over well before Christmas 2015.

It is also interesting to note that at the end of January and during February water levels on Lake Muskoka trended towards the top end of the operating range or about 9.4 meters on the Primary Water Level Chart, similar to the normal mean in November and December.

The thin ice on the major lakes greatly shortened the season for snowmobiling, ice fishing and construction of docks and boathouses.

The Beaumaris water levels were drawn down gradually, but remained at the high end of the MRWMP target operating range during February and bottomed out at just above 9.0 meters around March 10th.  In the previous year the lake draw down bottomed out at 8.6 meters on about April 1st which was near the bottom of the operating range.   Why wasn’t the water drawn down lower in 2016?

My hypothesis is that the MNRF was cognisant of much lower snowfall this past winter verses the winter of 2014-15 ( My wife who records snowfall in Beaumaris tells me it was 50 inches less).   Based on this they anticipated a much smaller spring freshet and wanted to make certain there was sufficient water in the watershed, so it was kept higher.  Concern for lake trout eggs, ice integrity for snowmobiles, construction and ice fishing, may have been other factors for not drawing the levels down faster.

It is interesting to note that had the Spring of 2016 been similar to 2015 and water draw down rates for Feb and March 2016 continued, the lake levels by April 1st of both years would have been almost identical.    So what happened?

First we had unusually warm weather from March 7th to 17th and again from March 27th to April 1st.   This caused the premature melting of the snowpack.   Second we had 157 mm of precipitation, double what is considered normal in March, with 87 mm falling in 3 days at the end of March.   In addition ice out in the main bodies of the big 3 lakes occurred almost a month early verses, what is considered normal.  The end result saw water levels climb over 1 meter between March 10th and April 12th in spite of water exiting the system as quickly as the management plan permits.

Ice Damage:

With water levels above many peoples’ docks and boathouse floors, the temperature turned cold ( significantly below freezing at night) from Apr 2 to 10th This resulted in the formation of large sheets of ice on the open lakes, that normally would be still frozen at that time of year.   I am not sure of the exact timing, but during the first full week of April the wind broke up much of the ice sheets that formed and blew the ice across the lakes to the windward shore.  Since the ice was above the boathouse floor it found little resistance to push against structures like boathouses and docks thus crushing them with the tremendous weight of the ice and the force of the wind (A square kilometer of ice an inch thick weighs in excess of 25,000 tonnes).

Township of Muskoka Lakes Actions:

The TML has no responsibility or authority to manage and control water levels in our Township or on the watershed.   The responsibility rests with the MNRF who attempt to manage the system within the parameters established in the Muskoka River Water Management Plan (MRWMP).    This plan was established in 2006 and was due to expire March 31, 2016.

Based on direction from TML Council, Deputy Mayor Baranik, District Councillor Harding and I were successful in obtaining a meeting with the MNRF Minister’s Parliamentary Assistant, Eleanor McMahon on February 22nd.    We reviewed the pending expiration of the MRWMP and provided her and other MNRF Policy Advisers at the meeting with our briefing paper.  The briefing paper outlined the TML’s concerns with the expiration of the MRWMP and made eight suggested improvements for a renewed management plan.

During a subsequent discussion that I had in late February with the MNRF Parry Sound Regional Manager, I learned that the MRWMP had been extended to March 31 2021.

In mid March I wrote to Parliamentary Assistant McMahon expressing TML’s concerns that the status quo on the MRWMP was unacceptable and that modifications needed to be forthcoming to address numerous concerns. Variability of water levels being only one of the major issues.

On April 4th I received a letter from MNRF Minister Mauro advising me that the MRWMP was being extended for 5 years.  It is only in rare cases that they would address any water management plan, while they were reviewing and preparing to update the umbrella Lakes and Rivers Improvement Act (LRIA)

Subsequently Councillor Harding and I had discussions with the District Chair and District Staff with responsibility for the Muskoka Watershed Council. At the April TML and DMM Council Meetings District Councillor Harding introduced resolutions to request that the MNRF conduct a review of the Muskoka River Water Management Plan and initiate consultations to identify the limitations of the current operating plan and prepare an impact study to address current concerns.

Chair Klinck subsequently sent a letter dated April 26, 2016 to Minister Mauro reaffirming our concerns in the DMM and TML Resolutions, with copies to several other impacted municipalities and politicians in the provincial and federal governments.

Advice:

  1. Be aware of the dangers involved in constructing docks and boathouses in areas that should be considered flood plains.
  2. When rebuilding a dock or boathouse raise it as high as practical to minimize the adverse impact of the inevitable flooding.
  3. If possible locate boathouses in bays or away from the direct impact of large waves and ice driven over large bodies of water.
  4. Keep all personal or easily damaged articles well above the 100 year flood level in your boathouse.

Sincerely

Don Furniss, Mayor