High Water

Posts related to Shuswap Lake high water

July 2, 2020

As first reported in our June 27 update, the Provincial River Forecast Centre has maintained the Flood Watch advisory for the South Thompson watershed. The Centre defines a Flood Watch as follows:

  • River levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur.

The River Forecast Centre have also maintained a High Streamflow Advisory for the tributaries to the South Thompson River including Shuswap River, Shuswap Lake and Adams River. (A high streamflow advisory is defined as – River levels are rising or are expected to rise rapidly, but no major flooding is expected. Minor flooding in low lying areas is possible.)

Monitoring of the recent River Forecast Centre predictions and observed lake levels have all indicated the slow decrease in the lake level over the past few days. However, the Forecast Centre information has consistently indicated that we can expect Shuswap Lake levels to increase by approximately 0.2 m between July 2nd and July 4th or 5th before lake levels again start to slowly decrease. As the high elevation snowpack continues to decrease steadily the wildcard in the predictions will be in how much rain we continue to receive over the next week. With generally drier weather forecast for next week, hopefully the predictions hold and we are nearing the end of the spring freshet runoff.

SWOA will continue to monitor the predictions from the River Forecast Centre as they are released over the next week and will provide an update if there is a change in the forecasted lake levels.

Flood Watch Advisory for the South Thompson Watershed June 27, 2020

The Provincial River Forecast Centre has issued a Flood Watch advisory for the South Thompson watershed. The Centre defines a Flood Watch as follows:

  • River levels are rising and will approach or may exceed bankfull. Flooding of areas adjacent to affected rivers may occur.

Note that the advisory applies to rivers but, due to the linkage between river levels and Shuswap Lake levels, issuance of the advisory does indicate that Shuswap Lake levels could increase and remain high for some time.

Our posting on June 24th indicated that Shuswap Lake levels would increase by next Wednesday increasing to a peak on June 29 and 30. However the current forecast predicts that these levels, rather than starting to decrease, would remain elevated until at least July 5th.

SWOA will continue to monitor the predictions from the River Forecast Centre as they are released over the next week and will provide an update if there is a change in the forecasted lake levels.

June 24, 2020

In our post on June 21st we reported that Shuswap Lake levels would remain near the current level (349.02 m) over the next week and then start to decline slowly at the end of June. The forecasts on June 22 and 23 reinforced the June 21st prediction. However, todays 10 day forecast from the Provincial River Forecast Centre indicates that South Thompson River discharges will remain near current levels until June 28th and then increase on the 29th and 30th before starting to decrease steadily in the first few days of July. This means that we can expect an increase in the level of Shuswap Lake of 0.16 m (0.52 feet) early next week followed by a decline of 0.1m (.33 feet) by the July long weekend.

SWOA will continue to monitor the predictions from the River Forecast Centre as they are released over the next week and will provide an update if there is a change in the forecasted lake levels..

Lake levels can be viewed by clicking here.

In our post on June 12th, we speculated that Shuswap Lake might remain stable near the annual peak over the following 10 days, possibly increasing by as much as 0.22 m (0.7 ft) to a peak on June 20th. Well, with the variable weather over the past week we were right that the lake should remain stable near elevation 349.0 m but it did not rise as predicted. SWOA has been monitoring the daily river discharge predictions released from the Provincial River Forecast Centre over the past week (each of which look 10 days into the future) and a clearer picture is starting to emerge. The most recent predictions are indicating that the level of the lake will remain near the current level over the next week and then start to slowly decrease at the end of June. This prediction is consistent with observed decreases in the high elevation snowpack across the watershed and the decreases in river discharge being observed in both the Salmon Arm and Shuswap Rivers. As well, the generally drier weather forecasts for the next week will contribute to this trend.

SWOA will continue to monitor the predictions from the River Forecast Centre as they are released until the end of June to make sure that the expected trend continues.

Lake levels can be viewed by clicking here.

In our post on June 9th, we speculated that Shuswap Lake might remain stable near the annual peak over the following 10 days. Lake levels have dropped 0.1 m (0.3 ft) over the past 3 days but the Province’s forecast indicates that in flow in the South Thompson River flow will increase over the next 10 days, likely in response to the wet weather that is forecast over the watershed in the next week. Lake levels are expected to increase in the following week by 0.22 m (0.7 ft), reaching a peak on June 20th.

We will continue to monitor this information over the next 10 days as it is released by the Province to confirm the prediction for the date and elevation for the annual peak for the lake.

Lake levels can be monitored by clicking here.

In our post on June 4th, we speculated that Shuswap Lake might near the annual peak by today. Well, we were both right and wrong. Lake levels have dropped slightly over the past 5 days (0.06m(0.2 feet)) but with the remaining snow pack in the southern portion of the watershed, the Province’s recent forecasts are suggesting a further small decrease in flow in the South Thompson River followed by a small (and we hope the last) small increase in river flow. These changes translate to a small decrease in lake levels over the next few days followed by a small increase in the following week so that the lake level will peak between June 15th and 17th. Likely you won’t notice much change in the lake level over this period.

We will continue to monitor this information over the next 10 days as it is released by the Province to confirm the prediction for the date and elevation for the annual peak for the lake.

Lake levels can be viewed by clicking here.

In our post on May 31st we did wonder if the predicted peak of Shuswap lake was just a blip and that levels would continue to increase due to the relatively high snow-pack levels in the southern part of the watershed. Well, with the warm weather and rain lake levels did continue to rise beyond the earlier forecast. However, the latest two Provincial forecasts indicate that Shuswap Lake levels are nearing their annual peak. Lake water levels have increased 0.45 m (1.48 ft ft.) since May 31st. Based on the Province’s recent forecasts for the increase in flow in the South Thompson River, we expect lake levels to continue to slowly rise a further 0.10 m (0.32 ft) over the next week, reaching a predicted peak on June 9th or 10th. It appears lake levels are nearing the annual peak,

We will continue to monitor this information over the next 10 days as it is released by the Province to confirm the prediction for the date and elevation for the annual peak for the lake.

Daily lake levels can be viewed at Shuswap Lake Website.

As reported in our posting on May 25th, Shuswap lake levels have continued to increase steadily with the warmer weather, combined with some rain, rapidly melting the mid-and high level snowpack. Shuswap Lake water levels have increased 0.53 m (1.73 ft.) since May 25th. Based on the Province’s forecast of the increase in flow in the South Thompson River for May 31st, we expect lake levels to continue to rise a further 0.52 m (1.7 ft.) over the next 5 days with the daily rate of rise slowing over that period. Based on today’s forecast, Shuswap Lake should reach a peak on June 5th or 6th.

We will continue to monitor this information as it is released by the Province, especially to see if this is a pause in the runoff resulting from cooler weather or if, with increasing contributions from the southern part of the watershed, there could be a further increase in lake water levels.

Daily lake levels can be viewed at Shuswap Lake Website.

Wednesday, May 27, 2020

The Shuswap Emergency Program has sand and bags available for residents who may be at risk of flooding.

Sand and bags are being made available to the public at 20 locations in the Shuswap area.  Please visit CSRD website for specific locations, details or any restrictions on availability.

Click here to view the CSRD website for locations or click here for a pdf map.

As reported in our posting on May 22nd, Shuswap lake levels have continued to increase steadily with the warmer weather, combined with some rain, rapidly melting the mid-level snow pack. Shuswap Lake water levels have increased 0.32 m (1.05 ft.) since Friday. Based on the Province’s forecast of the increase in flow in the South Thompson River, we expect lake levels to continue to rise a further 0.52 m (1.7 ft) over the next 10 days. The current rate of lake level increase continues to track the water level rise experienced in 2012 although the timing is earlier than occurred in that year. If this trend continues we would expect the lake to peak in the second week of June.

Review of the snow pillow data shows that the melt of the high elevation snow pack in the northern part of the watershed (Celista Station) is continuing while in the southern part of the basin (Park Mountain and Enderby stations) has yet to get underway (these latter stations are at a slightly higher elevation). This means that there is still a substantial quantity of water in the mountains surrounding the lakes and, as indicated in the Province’s Bulletin, there remains a risk of flooding due to snow melt and/or heavy rainfall.

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.