Point 13 – Lake Level Management and Water Control Issues
As most Crystal Lake ratepayers will know, there is a water control structure at the north end of the lake. This structure was re-built in 1999 and allows limited control of the lake level. As most people will also know, there have been issues with managing the lake level and associated issues with the control structure. Lake levels are affected by spring runoff, rainfall throughout the summer and evaporation. Crystal Lake being spring fed and isolated from any incoming rivers or creeks is not subject to extreme water level fluctuations.
The water control structure consists of a metal culvert which is approximately 100 metre long (60 mm or 2 foot diameter) which connects Crystal Lake to the Lily pond. Halfway along this culvert is a stop log type water control structure. This stop log structure allows the water to be maintained or released by adding or removing stop logs.
The lake level or full supply level (FSL) is dictated by the provincial government and delegated to Water Security Agency (WSA). This level is established at 493.05 metres above seal level. The Hamlet Board (HB) has no authority to intentionally maintain a higher level, nor a lower level. Historically the lake level is highest in the spring and stop log(s) are removed so the lake will drain until FSL is reached. The guideline is to have the lake level stabilized at the FSL by July 1st of each year.
Note: The HB retained the services of a legal surveyor (Altus Group) in spring 2020 to determine the elevations of the system. It was determined that the elevation of the stop logs and culverts is essentially correct, the structure has not shifted or settled significantly.
This spring, lake levels were high (approximately one foot above FSL) and this caused some shoreline erosion. Attempts to lower the lake was impeded this spring was impeded by beaver activity and sand infiltration into the culvert.
Beaver dams were preventing the flow of water from the lily pond into the existing creek system which allows water to reach the Assiniboine River. This caused the level of the lily pond to rise therefore limiting flow from the lake itself. These dams had to be removed on multiple occasions
Secondly, there was significant sand built up inside the culvert, impeding flow. This sand build-up has occurred in the past and requires a vacuum truck to remove the sand within the culvert, thus allowing the free flow of water. The HB applied for an Aquatic Habitat Protection Permit which is required to alter the bed, bank or boundary of any water body. Unfortunately, communication issues resulted in the work being completed before the permit was issued. The HB was issued a ‘Warning of Non-Compliance’ letter for conducting work near a waterbody without the required permit. The HB will reapply for a 5-year permit to enable future work to be conducted and ensure all regulations are followed.
Issue 1 Beaver Dams Restricting Flow of Water
Beavers activity has been a longstanding concern and the HB has an annual budget item to deal with this issue. A trapper/blaster is periodically brought in to remove beaver dams and to control the beaver population in the lake, lily pond and creek.
Issue 2 – Sand Infiltrating the Culvert
The culvert itself is a relatively small diameter, compared to the size of the lake, and must be working efficiently in order to effectively manage lake levels. If there are any impediments, the flow can be greatly reduced or even prevented. Sand can readily enter the culvert due to wave action and waterflow and impeding water flow.
The HB has been in discussions with the WSA and a private engineering consulting firm requesting advice as to how to reduce or eliminate the sand infiltration. WSA does not provide engineering services to third parties and therefore has not been able to provide any advice.
Issue 3 – Beach Erosion Near the Culvert
The installation of the water control culvert is suspected of causing significant beach erosion in front of at least 5 cabins situated immediately to the west of the culvert. This has been a longstanding concern for these cabin owners and the HB recognizes the issue. Past discussions with the WSA resulted in five options being proposed.
Bring in sand to re-establish beach and install a breakwater
Construct barriers extending into the water (groynes) west of the eroded area to capture sand
Shorten the culvert
Lower the culvert
Reverse the boat direction
As a number of these recommendation would require heavy equipment with its associated cost, the HB is pursuing professional engineering advice as to which option would be most effective. Again, WSA declined to offer engineering advice, even though the water control structure was designed and constructed by a section in SaskWater, which now is part of the WSA. Further work is required for professional engineering advice and designs.