Upper Rideau Lake
| Upper Rideau Lake | |
|---|---|
| Location | Ontario |
| Coordinates | 44°40′55″N 76°20′10″W / 44.682°N 76.336°WCoordinates: 44°40′55″N 76°20′10″W / 44.682°N 76.336°W |
| Primary inflows | Westport Sand Lake |
| Primary outflows | Big Rideau Lake |
| Catchment area | 61 km2 (24 sq mi) |
| Basin countries | Canada |
| Max. depth | 23 m (75 ft) |
| Surface elevation | 124.65 m (409.0 ft) |
| Settlements | Village of Westport, Village of Newboro |
Upper Rideau Lake is located in the municipality of Rideau Lakes, United Counties of Leeds and Grenville in Eastern Ontario, Canada. It is in the Saint Lawrence River Drainage Basin, and geographically the highest lake on the Rideau Canal System.
Upper Rideau Lake is the summit of the Rideau Canal system, with a surface elevation of 124.65m above sea level. Despite having the highest elevation, Upper Rideau Lake is not the top of the watershed. Water flows north to the Rideau River, there is no flow south to the Cataraqui River.
Inflow is from Westport Sand Lake, part of the Rideau Lake Subwatershed.
Outflow, through the Narrows Lock, is to the Big Rideau Lake, which eventually flows to the Saint Lawrence River via the Ottawa River.
The Rideau Lake Fault (an ancient fracture in the Earth's crust due to tension) explains the large exposure of granite that can be observed on much of Upper Rideau Lake's northern shore. The northern half of Upper Rideau Lake is located in the Algonquin Highlands. Bedrock in this hilly, Precambrian landscape consists mostly of gneisses and marble and is covered in a very thin layer of mixed glacial sediment. The southern half of Upper Rideau Lake is located between the Algonquin Highlands and the Smiths Falls Limestone Plain. Bedrock here consists of Paleozonic quartzose sandstone, dolostone, and conglomerate covered in a variety of sediment; mixed glacial sediment, sandy glacial till, silt and clay, organic deposits, and sand.
Before the creation of the Rideau Canal (1826-1832), Upper, Big, and Lower Rideau Lakes were one lake. The original plan was to have it remain as one lake by excavating the naturally rocky shallows on the Upper Narrows. When this proved difficult and expensive, Lt. Colonel John By finalized plans to build a dam and a lock (now Narrows Lock), separating and therefore creating Upper Rideau Lake. The creation of Narrows Lock raised the water in this area by approximately 8 feet (2.5m). This flooding created some immediate changes to the land. Drowned shorelines resulted in a number of newly created marshes and many dead standing trees.
Water levels along the Rideau Canal system are carefully monitored by the Ministry of Natural Resources and Forestry and Parks Canada. Water levels are managed for recreational purposes, allowing for adequate draft during the navigation season and for residents with docks, boathouses, and shorefront. In late May water levels are at their maximum, gradually declining throughout the summer, reaching the lowest point in October to the winter operating level. During this cycle the range of water height is approximately 1 meter.
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Wikipedia