Current Snow Survey and Water Supply
Now that April has arrived and the Shuswap lake level has started to increase in response to the low level snow melt, it is time for an update on anticipated runoff as promised in our last posting. Recent articles in the press and on television have emphasize the increased risk for flooding in some BC watersheds so we have looked at the April 1, 2018 Snow Survey and Water Supply Bulletin prepared by the BC. Provincial River Forecast Centre (https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/drought-flooding-dikes-dams/river-forecast-centre/snow-survey-water-supply-bulletin). As we reported last month, it is still early to come up with a definitive answer to whether we could expect flooding issues on the Shuswap, the snowpack indices in the South Thompson watershed have decreased slightly in the past month but remain above normal (109% of Normal). This is less than conditions for this time of year in 2016 but slightly more that for 2012, when we had very high water.
To put this all in context, typically 95% of the annual snow pack will have accumulated by April.
The volume runoff forecast for March to July, which includes runoff from snow melt and rain, is down slightly (103% vs. 104% of normal from last month). This measurement is for the outlet of South Thompson River at Little Shuswap Lake near Chase. The lake is still currently about 0.3 m lower than normal so this information suggests that we should not expect above normal lake levels this year.
Of course the wildcard is the weather. A cool wet remainder of April followed by above normal air temperatures in May that brings off the snow pack faster would change this outlook.
We still remain cautiously optimistic and will give you an update when the May 1 water supply bulletin is available.
Click on the date to view the current Snow Survey and Water Supply Bulletin for April 1, 2018.