Understanding Carleton Place Dam
Mississippi Lake, one of the largest inland lakes in south-eastern Ontario, is the last major lake on the river system and is found in the Townships Drummond/North Elmsley, Beckwith and Mississippi Mills. Mississippi Lake has two basins separated by a long narrow channel at Squaw Point:
1) South basin; the deeper portion of the lake
2) North basin; between 2.0 and 3.0 m deep
The Carleton Plan Dam is a water control structure and is located within the Town of Carleton Place, just downstream of Mississippi Lake. The dam is a concrete structure (owned by MVCA) with five sluices containing a total of 48 stoplogs and a 75 m overflow weir, which regulates the water levels upstream of the dam for most of the year. There are a total of ten stoplogs in each of the first three sluices and nine stoplogs in the last two sluices, with all stoplogs being 0.25 m x 0.25 m x 4.25 m. The weir elevation is 133.92 m and the normal operating range for the dam is 133.93 m to 134.50 m. The weir was designed for the use of flashboards, but they have never been placed on this structure. The dam has a total drainage area of 2876 sq km and a total storage capacity of 3787 ha m.
Seasonal Management Strategies
As water levels increase in the spring, additional stoplogs are removed to keep ice on the river and the lake as stable as possible.
Once 25 logs are removed from the dam, its influence on upstream flood levels is effectively negated and operations are undertaken to keep levels in the river below 134.50 m.
As streamflows and water levels recede, stoplogs are replaced with the objective of having the lake at an elevation of 134.35 m for the long weekend in May.
The summer target range is between 134.00 m. and 134.35 m.
The dam is not operated over the summer unless significant precipitation increases water levels on the lake above 134.35 m.
Between 10 and 20 stoplogs are removed from the dam (depending on streamflows) and fall/winter water level is targeted between 133.95 m and 134.20 m.