Overall seasonal water runoff volume for the basin that feeds the Columbia River was nearly one-third greater than its seasonal average in the first half of 2011, according to figures recently released by BC Hydro.
As of late December, the total runoff — Canada and U.S. combined — came in at 133 per cent of average (January to July, 2011), with runoff conditions for the Columbia/Kootenay basin within Canada at about 115 per cent above average.
The mammoth snow falls recorded in the latter parts of 2010 and the first few months of 2011 played a significant role in the runoff recorded.
“Runoff conditions this year were well above normal due to high snow pack levels, primarily in the lower portion of the basin,” read a BC Hydro report.
Currently, levels in the West Kootenay’s three reservoirs — Arrow Lakes, Duncan and Kootenay Lake — are either decreasing or have no change.
The Arrow Lakes reservoir is about 434.4 metres (1,425 feet) measured at the Fauquier gauge. The reservoir dropped .5 m. (1.6 ft.) over the past week. It is expected to drop across December and January to reach between 428.2 to 431.3 (1,405 to 1,415 ft.) by the end of January.
Kootenay Lake is holding steady at 531.7 m. (1,744.4 ft.), while Duncan Reservoir dropped .61 m. (two ft.) over the last week to 568.7 m. (1,865.7 ft.). Duncan is expected to drop by 7.2 m. to 559.3 m. (1,835 ft.) by the end of January.
The Arrow weekly average discharge was 56 thousand cubic feet per second (kcfs), Brilliant was 26 kcfs while Duncan Dam was eight kcfs.
The actual elevation of reservoirs is influenced by snow pack, inflow levels, weather patterns and other factors such as load requirements.
The official water supply forecast for 2012 will be issued later this month.