OSOYOOS TIMES-April 14, 2010

By Paul Everest – Osoyoos Times

The International Osoyoos Lake Board of Control has announced that 2010 will be another drought year for Osoyoos Lake.
The board, which is an international body responsible for monitoring and controlling water levels in the lake, made the drought declaration on April 8.
When a drought year is declared for the lake, the lake level is maintained at a height between 277.5 metres and 278.2 metres from April 1 to Oct. 31 through management of the Zosel Dam in Washington state.
In a normal year, the level of the lake is kept between 277 and 277.8 metres.
Whether a drought year is declared depends on criteria such as the expected summer outflow from the Similkameen River and Okanagan Lake and the water level in Okanagan Lake.
According to a media release from the board, this year’s drought declaration is based on an April 1 forecast from the U.S. National Weather Service for the Similkameen River’s volume of flow from April to July.
The service is forecasting a flow volume of “865,000 acre-feet.”
According to the orders set out by the International Joint Commission which the board follows when determining whether a year is a drought year, a drought can be declared if the “volume of flow in the Similkameen River at Nighthawk, Washington for the period April through July as calculated or forecasted by United States authorities is less than 1.0 million acre-feet.”
One acre-foot converts to 1,233 square metres.
Should precipitation and river flow conditions change, the board can rescind the drought order before Oct. 31.
This is the second year in a row that a drought year has been declared for the lake.
Since 2000, drought years have been declared six times, including this year, although the declaration in 2004 was rescinded.
Drought-year declarations for the lake are often tied to dry weather conditions around the province.
The same day the declaration was made, the B.C. Environment Ministry released its latest data on provincial snowpacks and water supply levels.
According to the  snowpack and water supply bulletin, “as of April 1, with the exception of high-elevation areas on Vancouver Island and the South Coast, snowpacks across B.C. are all below normal.”
The bulletin also states that the Similkameen basin has the lowest snow water levels in the province at 64 per cent and snow water levels in most areas, including the Okanagan Valley, declined last month.
The Okanagan and Similkameen areas are listed in the bulletin as being between 65 to 85 per cent below normal snowpack levels for this time of year.
“The East Kootenay and Similkameen basins stand out as having particularly poor snowpacks,” the bulletin states.
Typically, by the beginning of April, more than 95 per cent of the winter’s snow has accumulated.
Provincial Environment Minister Barry Penner said below-normal snowpack conditions in areas such as the Okanagan basin “indicate potential for water-supply challenges to develop during the summer.”
“The low snowpack and smaller than normal snowmelt runoff may be reflected in such things as lower than normal lake and reservoir levels, lower than normal recharge of groundwater aquifers, and lower than normal river levels during summer,” a ministry press release states.
The below-normal snowpack levels are being blamed on warm and dry conditions caused by a moderate El Nino weather pattern over the past three months.
“Much of central and southern B.C. experienced well above normal temperatures during January, February and the first half of March,” the ministry’s press release states.
“As a result of the unseasonably warm weather, melt of low- and mid-slope snow occurred in most areas of the Coast and Interior.”
According to the ministry, this spring will need to be a wet one in order to reduce the possibility of drought problems or low-flow conditions in rivers this summer.
“Spring rainfall (April, May and June) will need to be at or above normal,” the ministry’s release states. “The first week of April has been cool and wet. However, the long-range seasonal forecast from Environment Canada is for warmer than normal weather over the next three months.”
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