Cottage Owners' Association and Lake Plan

Water Levels

Water Levels

by Chris Riddle, Past TSW Liaison for KLCOA and co-chair of CEWF

The water level on the Kennisis lakes is controlled by a Trent Severn Waterway (TSW) dam where the outflow from our lakes feeds the Kennisis and then the Gull rivers before entering the Trent River. 

The TSW uses the Kennisis lakes as a reservoir, lowering the lake in summer to maintain sufficient draught for the main navigation channel on the canal portion of the TSW.

The dam is comprised of nine 12” wooden logs plus a 6” metal “half-log”. With all the logs in place the top of the dam is therefore 9 feet 6 inches above the sill plate of the dam. In recent memory, the TSW leaves 3 logs in place all year resulting in a useable control range of 6 feet 6 inches.

Kennisis Lake Average Water Levels

The following chart records the multi-year average water level (blue line) on Kennisis Lake since 1988. An indication of the potential variability of water levels is provided by the maximum (red line) and minimum (green line) water levels recorded over the same period.

Data provided by the Trent Severn Waterway

How to Read the Chart

Water levels are measured by the Trent Severn Waterway (TSW) using a gauge located at the Kennisis Dam. The water level is measured in metres (m) above the sill plate of the dam.

Key reference points:

            Sill plate level                                             0.00m             0% full

            Height of standard stop-log                         0.305m

            Height of dam with all 9.5 logs in place       2.90m             100% full

            TSW Target level in Spring                          2.84m             98% full

            TSW Winter set level - 3 logs in place        0.92m             32% full

            Nominal water level fluctuation                  1.92m             66% of capacity

Current Water Level Data

To check the current water level on a reservoir lake you can use visit the TSW web site http://www.pc.gc.ca/lhn-nhs/on/trentsevern/visit/ne-wl/trent_e.asp

Click here to see the 2012 Levels as compared to the average.

NOTE: While the water level of the lake is ‘controlled’ by the number of logs in the dam, it will rarely be exactly equal to the level of the topmost log in the dam. It is usual for there to be a ‘head’ of water of several centimeters above the top of the dam; it is also possible for the water level of the lake to drop below the level of the topmost log in the dam due to evaporation or the recent addition of a stop-log.

What are the Preferred Water Levels for the Kennisis Lakes?

As a Member of the Coalition for Equitable Water Flow (CEWF), in 2011 the KLCOA identified challenges facing KLCOA members due to the water management practices of the TSW. In particular, we identified problems related to flooding, water access and safe navigation resulting from water level fluctuations.

CEWF is promoting the concept of a lake-specific Preferred Water Level Range during the principal navigation season from mid-May to mid-September.

With the help of data collected by KLCOA Member Doug Lenart, we have focused on the ability to safely navigate between the main lake and Little Kennisis Lake as well as Paddys Bay. This is not the only issue of concern, but it can be quantified with measurable data and solving this issue would also solve other problems. The data collected include a profile of the navigable channels under the bridges as well as clearance and draft specifications for the most common boats found on our lakes. This allows us to calculate the range of water levels that allow for safe navigation between the lakes.

As a result of this analysis, it is proposed is that the TSW be requested to manage the water levels on Kennisis Lake between mid-May and mid-September so that:

  • The water level not rise above 95% of the full range available for control by the TSW. This is equivalent to a water level that is 4" below the top of the dam with all logs in place. This level is equal to the multi-year average for early June. Ensuring that the water level did not exceed this upper limit would also help to avoid shoreline erosion and flooding of low-lying properties;
  • The water level not be allowed to drop below 55% of the TSWs control range. This is equivalent to 51" below the top of the dam. This level is equal to the multi-year average for September 1st. Ensuring that the water level did not fall below this lower limit would allow safe passage between the lakes, reduce the number of navigation hazards, and also reduce the risk of docks being left high and dry in September.

The overall result would see Kennisis Lake drop about four feet over the summer months instead of five feet as in 2012 or even six feet, as happened in 2007.

KLCOA members supported this approach at the September 2011 AGM, and the information was forwarded to CEWF and then to the TSW along with similar input from other lakes in the Haliburton.

 

Kennisis Lake Preferred Water Levels compared to Historic Water Level Data

The Chart below provides the following additional information:

1.         The Preferred Water Level range during the navigation season from May through to Thanksgiving (shaded area between upper and lower preferred limits) – as approved by the KLCOA Members.

2.         The TSW winter log-set level (purple line) shown for December & January)

Note:   the left scale is still in metres above the sill plate of the dam:

however the scale increments by 0.3 metres, equivalent to the depth of one of the control logs used to adjust the height of the dam.


From the chart it can be seen that:

-     the winter-set condition is equal to 3 logs in the dam;

-     the preferred upper limit of 2.75 m for the water level during the navigation season, equivalent to 9 logs in the dam, corresponds to the multi-year average high water level and so should be attainable.

-     the preferred lower limit of 1.6 m for the water level during the navigation season, equivalent to 5 logs in the dam, is typically breached in September, or as early as August in a dry year: however this level has been maintained in the past as shown by the historic maximum. It would appear that this condition could be satisfied most years if the winter-set condition were 4 logs instead of 3.

Worked example: Navigation under the Bridge between Big and Little Kennisis Lakes

Of the 1047 waterfront properties on the Kennisis lakes, 286 are located on Little Kennisis Lake. Navigation between the only marina on the lake and Little Kennisis Lake requires passage under a road bridge. The channel is shallow and there is limited clearance under the bridge. If the water level is too high, some boats do not have sufficient clearance. If the water level is too low there is inadequate draft.

 

An analysis of the channel profile plus an evaluation of boat characteristics has been conducted. The following is a summary of the findings:

  • the bottom of the centre of the channel is 0.3 m above the sill plate
  • the channel profile is a regular ‘shallow-saucer’ shape
  • assuming the navigational channel occupies 60% of the overall width of the channel there are high-spots that are 0.8 m above the sill plate.
  • The underside of the bridge roadbed is 4.6 m above the sill plate
  • Most boats could pass under the bridge if there was a minimum clearance of 1.8 m
  •  There is thus sufficient clearance at a water level of 2.8 m (close to TSW’s full condition)
  • Most boats require a draft of less than 0.8 m
  • There should therefore be sufficient draft if the water level is greater than 1.6 m
  • This allows TSW an operating range during navigation season of 1.2 m (1.6 to 2.8 m or between 5 & 9 logs in).

 An environmentally acceptable approach to dredging the channel to remove ‘erratic’ rocks would be desirable and would allow for greater fluctuation in water level without impacting navigation.

Paddy’s Bay Bridge

A second bridge providing access from the main lake to Paddy’s bay has been profiled as well. Although the channel is about 1.0 m above the sill plate and the underside of the roadbed is 4.2 m above the sill plate, it is typically smaller boats that use this channel. No additional water level constraints are therefore deemed essential. Although dredging of the channel would certainly improve access. 

Please go to the “Contacts” tab on the Home Page if you wish to direct any comments or questions to Chris Riddle.

 

Manipulation of 12" log at TSW damManipulation of 12" wooden log at TSW dam

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