In the past 10 days, Shuswap lake levels have continued to increase rapidly with the warmer weather, combined with some rain, rapidly melting the mid-level snowpack. However, during the rain events there was further accumulation at the higher elevations.
The Province has issued its May 1 Snow Survey and Water Supply Bulletin confirming that the snow basin index for the South Thompson basin was well above normal (124%) for this time of year. Their forecast indicated that the warmer weather that occurred over this past weekend would initiate the high elevation melt but not substantially increase flows in most rivers. The spring snow melt is only one of the driving factors that will influence the occurrence of high water in Shuswap and Mara Lakes. Spring weather is also a critical factor influencing high water levels with the timing and severity of temperature and rainfall in the watershed being important factors irrespective of snowpack levels.
The current rate of lake level increase is tracking the water level rise experienced in 2012, similar to the lake level rise observed in 2018. Since our last report, the lake rose 0.71 m (~2.3 feet) and over the next 10 days the Provincial modelling indicates it could rise an additional 0.62 m (~2 feet) to approximately 347.5 meters, just slightly less than the peak lake level reached last year.
We are monitoring this information as it is released by the Province and will provide you with a weekly update or more frequently if there is a substantive change in the projections.
Lake Levels can be found at shuswaplakewatch.com