Water levels in the Arrow Lakes Reservoir will continue to drop through September according to BC Hydro’s fall update. The lack of rain over the course of 2023 is blamed as a major contributing factor
Most of the Columbia River valley is currently at drought level 5 (out of 5) and the rest of the Kootenay region is either at level 4 or 5.
During drought level 4, the B.C. government says adverse impacts to socio-economic or ecosystem values are likely. At level 5 adverse impacts are almost certain.
Residents and wildlife along the Arrow Lakes are witnessing those affects.
Many residents along the reservoir have begun to raise concerns about fish and the Kokanee spawning season.
BC Hydro says that fish stranding is not that uncommon and can happen in any year.
“We recognize that the impacts are more significant under the current conditions,” says Hydro spokesperson Mary Anne Coules.
“We are documenting all reports of fish stranding on Arrow Lakes Reservoir during this year’s drought conditions, and we have identified high priority sites.”
Crews are assessing these sites and will salvage fish where possible, provided it can be done safely.
Low water levels are also likely to impede Kokanee access at some locations this year. But Hydro says the main tributaries where kokanee are known to spawn are still connected to the reservoir.
Kokanee normally enter Arrow Lakes Reservoir tributaries for spawning starting in late August or early September with peak spawning activity by mid-September.
“Reservoir levels have not been shown to significantly affect kokanee or bull trout numbers,” explains Coules. “Overall factors, such as in-reservoir conditions that influence survival, are more important to overall kokanee numbers.”
Coules says Hydro is committed to protecting wildlife and the environment by reducing the impact their operations have on it.
They are working with the Fish and Wildlife Compensation Program and the province to survey creek mouths in advance of spawning migration to assess passage and collect additional water temperature data.
Ground and aerial counts for kokanee are underway as of this week.
As of Sept. 7, Arrow Lakes Reservoir levels were 426.7 metres. BC Hydro says they expect the reservoir to draft between the operating ranges of 426.8 metres (1,400 feet) and 422.1 metres (1,385 feet) by the end of September. But they will remain above the water license minimum level of 420 metres (1,378 feet).
It is expected that the water levels will continue to drop throughout the fall.
“While these levels are seasonally lower than average, they are not unexpected during low inflow conditions,” says BC Hydro.
Lower fall levels were also observed in the low inflow years of 2015 and 2001.
With drought conditions persisting throughout the province, below average reservoir levels are not unique to Arrow Lakes this year.
BC Hydro says the low levels are due to a combination of low precipitation since last fall, the early depletion of the below-average snowpack in May, and the severe drought conditions observed in the Columbia basin this summer.
“The combination of low inflows and required Columbia River Treaty discharges have resulted in a deeper than normal draft of Arrow Reservoir over this summer,” says BC Hydro.
Additionally, discharges from Kinbasket Reservoir that might otherwise keep Arrow higher, have been retained to ensure sufficient winter energy supply for Revelstoke and Mica Generation Stations.
BC Hydro says it has already taken a number of steps to help mitigate the impact of this year’s drought conditions on Arrow Lakes Reservoir including negotiating with the U.S. to hold back additional water in the spring which resulted in Arrow Lakes Reservoir being 2.4 meters (8 feet) higher from May to August.
They also say they are carefully balancing discharge from other reservoirs to help offset otherwise deeper drafts at Arrow.
Canada and the United States are currently in the middle of negotiations to update the Columbia River Treaty. Many residents along the reservoir are hoping that more stable water levels will be part of the new treaty.
Current water levels are not related to the navigational lock outage or operation of the spillway gates at the Hugh L. Keenleyside Dam.
The lock was closed throughout August for emergency repairs which are now complete, and the lock has reopened.
The navigational lock design allows BC Hydro to safely de-water the lock to complete repairs regardless of the reservoir elevation. The navigation lock is not used for water management or dam safety purposes.
Information on reservoir levels and river flows is available by calling 1-877-924-2444 or visiting bchydro.com.
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