The Slocan Lake Stewardship Society has published a report entitled “2010 Slocan Lake Preliminary Water Study” detailing the results of the results of the data gathering work they did in the fall of 2010. It can be accessed here at http://www.fileden.com/files/2010/6/17/2890140/2010%20Slocan%20Lake_Prelim.WaterStudy%5B1%5D.pdf .

More information on their studies and their work can be found on their website http://slocanlakess.wordpress.com

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Potential Drought Conditions for Kootenays

Note from Kindy Gosal, Columbia Basin Trust:

“The Snow Water indices in the Kootenay river Basin is about 64% of Normal.  The Snow Water indices in the Columbia river Basin is 88% of normal. Low elevation snowpacks in all areas are negligible. Unless we get a substantial amount of precipitation in the Spring Drought issues may become prevalent in some areas”.

Report from BC Ministry of Environment 

May 1st, 2010 Snow Survey Bulletin:  http://www.env.gov.bc.ca/rfc/bulletins/watersupply/

May 1st Basin Snow Index Map:  http://wwwt.env.gov.bc.ca/rfc/bulletins/Basin_Snow_Water_Index_May2010_740x666.png

May 1st Drought Index Map: http://wwwt.env.gov.bc.ca/rfc/bulletins/Drought_Map_May2010.png

Ministry of Environment Information on Drought:   http://www.env.gov.bc.ca/wsd/public_safety/drought_info/

Synopsis: 

The peak of the winter’s snowpack has accumulated and melt has now begun. Snowpacks declined in most areas of the province during April as a result of a drier than normal weather. With the exception of high elevation areas on Vancouver Island and the South Coast, snowpacks across B.C. are all below normal. Snowpacks in the South Interior (Nicola, Okanagan, Similkameen, West Kootenay, East Kootenay, Lower Columbia) and in the Northwest Interior (Skeena, Nass) are well below normal.  Given the current low snowpack conditions, notice of potential drought is included in this bulletin, although should wet weather materialize in May and June, it could reduce the risk.

Weather:

Weather across B.C. over much of the winter was dominated by the effects of a moderate El Niño. Much of central and southern B.C. experienced well above normal temperatures during January, February and March. As a result of the unseasonably warm weather, melt of low- and mid-slope snow occurred in most areas of the Coast and Interior.  Temperatures during April were at or slightly below seasonal normals.

Precipitation has been variable over the winter. For the South Coast, a series of Pacific frontal storms during January brought heavy rain. These storms also allowed significant snowpacks to develop on some high elevation areas on Vancouver Island and the South Coast.  February and the first half of March had below normal precipitation, but then frontal storms in late March produced further snow accumulations. For the Interior, snowfall from January to late March was well below normal. During late March, frontal storms arising off the Pacific swept across the Interior, bringing heavier than normal snowfall to some areas. Precipitation during April was above normal on Vancouver island, and the south and central Coast, but below normal for the south and central Interior, the Northwest (Skeena, Nass, Stikine, etc.) and Northeast (Peace). The Prince George – Quesnel – Fort St. James area of the Interior received near normal April rainfall.

Current Snowpack:

The peak of the winter’s snowpack has accumulated and melt has now begun. The general pattern of snow conditions across British Columbia as of May 1 has not varied significantly over the past couple of months.  Snowpacks have, however, declined in most areas during April (except for the South and Central Coast, and Vancouver Island) as a result of a drier than normal weather.  With the exception of high elevation areas on Vancouver Island and the South Coast, snowpacks across B.C. are all below normal. Snowpacks in the South Interior (Nicola, Okanagan, Similkameen, West Kootenay, East Kootenay, Lower Columbia) and in the Northwest Interior (Skeena, Nass) are well below normal.

Basin snow water indices across B.C. vary from a low of 37 per cent of normal in the Similkameen to a high of 105 per cent of normal on Vancouver Island. Basin snow water indices declined across the BC Interior during April.  Vancouver Island and the South and Central Coast experienced increases in water indices during April, as a result of being affected by frontal storm systems. 

Overall, much of central B.C. (Fraser, Thompson, Peace) has 80-90 per cent of normal snowpack.  The South Interior (Nicola, Okanagan, Kettle, Similkameen, Kootenay) has 37-76 per cent of normal snowpack. These basins all stand out as having particularly poor snow conditions.  The Skeena and Nass basins are also dry, at only 61 per cent, a notable decline from their 81 per cent level a month ago. 

BC Snow Basin Indices – May 1, 2010

Basin   % of Normal     Basin   % of Normal   

Upper Fraser    81%     Kootenay        64%   

Nechako 90%     Okanagan-Kettle 76%   

Middle Fraser   80%     Similkameen     37%   

Lower Fraser    95%     South Coast     90%   

North Thompson  91%     Skagit  82%   

South Thompson  87%     Vancouver Island        105%  

Nicola  52%     Peace   81%   

Columbia        82%     Skeena-Nass     61%   

 In most basins, low and mid elevation snow is absent or well below normal, following the warm weather of January, February and early March.  This is generally not well measured by the BC snow survey, which is biased towards high elevation locations.  Use caution in interpreting the basin snow index numbers reported here, as they may indicate greater snow water in some basins than is actually present.

Water Supply Outlook:

Conditions as of May 1 indicate a likelihood of well below normal freshet runoff during May and June, and low risk for freshet flooding in the major river basins (Fraser, Thompson, Skeena, Bulkley, Nass, Peace, Liard, etc.). Water levels on these large rivers began to rise in late April, and are expected to peak by late May or early June.

The well below normal snowpack conditions across much of the South Interior (Okanagan, Nicola, Kettle, Similkameen, West Kootenay, East Kootenay), along with the Skeena, Nass, and Peace river basins in the north, indicate potential for low stream flows and water-supply challenges to develop during the summer. The low snowpack and smaller than normal snowmelt runoff are likely to 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.

Snow conditions at the end of the winter comprise only part of the peak flow and water supply forecast picture. Weather during May and June has a large influence. To reduce the potential for summer low flow or drought problems, rainfall during May and June will need to be at or above normal.

The Province is developing a drought response plan that will be in effect in June.  However, given the current snow conditions, notice of potential drought is included in this bulletin.

Much of the South Interior (including the Nicola, Okanagan, Kettle, Simikmaneen, East Kootenay, West Kootenay and Lower Columbia) are currently classified at Drought Level 3 (Very Dry Conditions), where low stream flows and water supply shortages are highly probable unless significant rainfall occurs during May and June.  Water conservation is urged.  Water restrictions at the local level should be considered and drought management plans should be reviewed.

Much of the Central and North Interior (including the South Thompson, Cariboo, Upper Fraser, Skeena, Nass, Bulkley, and Peace) are currently classified at Drought Level 2 (Dry Conditions).  These areas have early indications of potential low stream flow and summer water supply shortages. Voluntary conservation, as well as planning at the local level and use of tools such as drought management plans, is urged.

_______________

Allan Chapman

Head, River Forecast Centre

BC Ministry of  Environment

4th Floor, 395 Waterfront Crescent, Victoria  BC V8W 9M2

PO Box 9362 STN PROV GOVT

Tel:  250-387-9472,  Fax:  250-356-1202

Website: http://www.env.gov.bc.ca/rfc/