Dam and lock at Lindsay
Because of efforts by the Scugog Lake Stewards, the City of Kawartha Lakes has approved repair of the Old Mill water barrier for their budget for 2017. For the problem, see below, part 3 of the post below. We will keep you posted about that work which will probably not start until the Fall because of fish spawning.
POST #1 of 3 — ABOUT THE TRENT-SEVERN WATERWAY DAM AT LINDSAY.
The Scugog Lake Stewards have have just completed a very extensive look at the dam and locks at Lindsay and their operation and especially how they affect Lake Scugog.
The current operation of the dam and locks at Lindsay is the responsibility of Parks Canada through the Trent-Severn Waterway. This complex waterway and all the locks are administered by Colin Clarke, Water Management Technician, out of Peterborough.
Lake Scugog has historically been treated differently than any other lake in the system in that it is NOT used as a “reservoir lake” or what is often called a feeder lake. Reservoir lakes are reduced on an equal percentage basis throughout the summer season to keep the busy canals running. (approximately 175,000 boats per season). WATER FROM LAKE SCUGOG IS NOT USED TO FILL ANY ASPECT OF THE WATERWAY INCLUDING THE LOWER SCUGOG RIVER nor is it used for power generation. Any water take-down other than flood control traditionally takes place in late fall and January, never in summer unless there are flood conditions.
The unadorned truth is that Lake Scugog only gets its water from its own watershed. The lake has a huge surface area in proportion to its depth which causes warm water and a high evaporation rate. On hot, windy summer days such as we have had all this summer, the level of Lake Scugog can lose almost a centimeter in one day from evaporation. This can make the lake level drop quickly from spring high levels all on its own. During drought years such as this, there is much less water entering Lake Scugog than what leaves in evaporation.
In 2007, a communication error between the Lindsay Lock Master and the Water Control Engineer resulted in two stop logs being left out of the dam for almost all of July during a very dry summer. The lake level plummeted. This was accompanied by a drought year. Low water resulted in wide mud flats at the shore and marooned boats. Rightly, there was great concern from the Township, businesses and the general public and a realization of exactly how important a healthy Lake Scugog is to our economy.
In the past, when the spring freshette runoff from snow pack in our woods made the level of the lake rise above the TSW’s “navigation range” of 249.45 m. above sea level, and the soil of the watershed was saturated; then the water management engineer would have stop logs removed from the dam to prevent flooding. Recently, it was agreed that 4 inches could be added to that controlled level and still not cause problems such as flooded basements, septic beds, or eroded shorelines. Therefore the new control level is 250 m. above sea level which is also the height of the dam when all possible stop logs are in.
If there is a possibility of flooding because of a thick snow pack in the woods and a prediction of more preciptation to come and the lake level rises alarmingly, even with all logs out on both sides of the dam, — it still takes several days to draw the water down as our lake is so big.
However, if there is little snow melt and spring rains don’t come, the Trent-Severn water management engineer cannot get more water into the lake than the 250 m above sea level range because of the overall nature of the Lindsay dam/lock/spillway and mill site. See Blog # 2 on this issue that follows.
In the fall of the year, the water managment technician takes the water level down to protect shorelines and structures from ice damage.
Keep in mind, the reason the lake is shallower than it used to be is not because of mismanagement of the dam, but rather the filling in of the lake by decomposition of lake plants, silt runoff from the ditches, roads, lawns, construction and poorly protected eroding shorelines around the lake.
The Stewards are working with all essential parties this year to try to ensure the optimum management in future years.
TRENT-SEVERN LINDSAY DAM INFORMATION # 2 of 3. PLEASE SHARE WIDELY. On Friday, July 8, the Scugog Lake Stewards met with Jewel Cunningham, Director of Ontario Waterways and Colin Clarke, the new Water Management Technician for the Trent-Severn Waterway. It was a very productive meeting that allowed the Stewards to voice our concerns and to reinforce the importance of the lake and its health to our Scugog community.
Our blog # 1 detailed the general operation of the dam at Lindsay but our meeting made us newly aware of technical complications (see above photo taken during early spring) involved in keeping the right amount of spring run-off water in our lake. Keeping too much can cause flooding; keeping too little can interfere with recreation and healthy habitat. There are added complications in protecting our water levels even after all the stop logs have been placed in the dam come mid-May or so for the summer.
The Scugog River Lock #33 (see the photo taken sometime in early spring – Lake Scugog side seen at the top) and area is actually composed of five parts all of which are important in water management in Lake Scugog.
PART # 1, The dam, composed of two concrete columns each allowing the insertion of six 14” x 14” stop logs. The top of the top log is 250 meters above sea level. There is very little leakage through spaces between these logs.
PART # 2, Probably the most concerning to us, is a long concrete spillway with a maximum height of 250.07 meters above sea level. That is only .07m (2.75 inches) above the 250m maximum height of the dam. This spillway was designed to carry off large volumes of water in times of flood when the dam is wide open. Any possible flooding could affect low-lying, older areas.
PART # 3 is what is left of the old mill. It is owned by the City of Kawartha Lakes. You can see the water flowing toward it at that time in the photo from the Lake Scugog side of the dam. It is supposedly closed off, but there are concerns that the structure within the mill is old and leaky and that there is considerable scour and flow through and under it. (See our blog # 3 in this series) The Trent-Severn Waterway has NO control over, or responsibility for, this part of the Lock # 33 area. There is no way of determining just how much (if any) water escapes by this route.
PART # 4 – the Locks This is a definite area of water loss throughout the summer. While don’t know exactly how many times the locks are opened in any given summer, below is a record of the number of boats that traveled through the Lindsay locks in the previous two summers. There are many boats and a lot of lock openings — although smaller boats can go through a smaller lock (which is not visible in the picture) under the roadway which uses a smaller volume of water.
Judgements by the TSW water management engineers about water levels are made daily based on readings from equipment on the dock at Caesarea and at the dam itself.
SO WHAT REALISTICALLY CAN BE DONE? In the spring, if there is little run-off from the snow-pack, the watershed will not be totally saturated; and if Environment Canada is predicting that the summer will be hot and dry, the danger of flooding then could be predicted as very low. All the logs could go into the dam much earlier. If there were unexpectedly large rainfalls, then the long spillway would still take away any excess. While that might give us only a few more weeks of higher water, that would be better than nothing.
Of course, the concrete spillway could be raised. But adding to the level of the concrete spillway (Part 2 in the photo) would be very dangerous because for every drought year there is an equal flood year (2015). We seem to have 4 year cycles of drought and rain. Unfortunately, on planning maps, the flood plain contours are only in 2 meter intervals, so it is currently impossible to determine how many areas around the lake would be truly vulnerable if lake levels were raised generally by the TSW. Law suits would follow for sure if TSW enacted permanent change in height for the spillway.
We will discuss with the City of Kawartha Lakes and Lindsay about improving the barrier in the Mill (see post # 3 in this series), but as in Scugog and everywhere, money is tight and such work would be of more benefit to Scugog than CKL.
Traditionally, logs have been left out of the dam in the spring to aid spawning in the Scugog River. However, the water level in Lake Scugog (the greater spawning area) must be considered too. To make changes here, we now have to speak to the Ontario Ministry of Natural Resources and Fisheries.
WE MUST STRESS, HOWEVER, THAT THE MAJOR CAUSE OF SUMMERTIME WATER LOSS IN LAKE SCUGOG IS EVAPORATION. OUR HUGE LAKE SURFACE AND RELATIVELY SHALLOW DEPTH COMBINED WITH WARM WATER, HOT AIR TEMPERATURES AND LOTS OF WIND CAN COST THE LAKE ALMOST A CENTIMETER PER DAY OF WATER DEPTH.
We have to stress the importance of the old mill in the whole Lindsay site.
In 1827, The Purdy’s, an American family, built the first dam on the Scugog River at the site of present-day Lindsay. The following year using the power from the head of water from the dam, they built a sawmill and then in 1830, a grist mill was constructed. This mill was destroyed by fire and but was rebuilt in 1869. It was destroyed again by fire in 1978. About 50 years ago the whole mill was capped and a 16 ft. wide wooden barrier was built to hold back the river from flowing through the mill. As a project to celebrate the recent millennium, the remaining structure and grounds were cleaned up and incorporated into a park. It is now the responsibility of, and maintained by, the Town of Lindsay in the City of Kawartha Lakes, not the Trent-Severn Waterway system.
The wood stop logs for this barrier in the mill are quite a bit smaller than that of the 14 x 14 logs in the dam and they seem to ‘leak like a sieve’ which is not surprising given that they are likely over 50 years old. (By comparison, logs in the dam are inspected regularly and changed out as required. Their life expectancy is a maximum of 30 years. The Lockmaster has plugged the gaps and braced the top of the logs so that leakage is essentialy non-existent.) The photo is of what can be seen of the logs that comprise the barrier and of the condition of the cap on this barrier area showing the poor condition of the concrete cap. It is believed that the top of the barrier is just slightly above the Trent-Severn Waterway spillway next to it.
The back side of the log barrier is closed to the public, however, there is considerable flow-through as can be seen in the following photo taken from inside the mill structure a week ago.
It is guessed that the potential of the barrier to fail is relatively high due to its age with the most stress on the logs during spring high water. Fixing it would be difficult and expensive.
The Scugog Lake Stewards will look into this further with the City of Kawartha Lakes and the Town of Lindsay to see what can be done.
Part # 5 — two 24 inch diameter pipes drawing water year around from the Lake Scugog side of the dam to fulfill the water needs of Lindsay. As Lindsay increases its population this draw can more than double because their water treatment plant has that capability. Scugog Township is on a Level III Water Response, which means we have severe restrictions on water use. Whereas, Lindsay has only been on a Level I water response, which means people can water lawns on odd and even days. The Lake Stewards are looking into this an endeavouring to help Lake Scugog as much as possible through changing response levels and urging other sources of water.