Siltation Study Grant Approved

On February 8th, 2021, the RDOS (Regional District of Okanagan Similkameen) entered into an agreement with the VLSA (Vaseux Lake Stewardship Association) and approved a grant of $30,500 for funding through the local conservation fund service, to conduct a study of siltation on Vaseux Lake.

The project proposal outlined by the VLSA is as follows:

The channelization and creation of dams on the Okanagan River took place in the 1950’s (“Channelization”). The Canadian portion of the Okanagan River from Okanagan Lake to Osoyoos Lake was channelled and shortened from 70 kilometers to 37 kilometers. Only 6 kilometres remain in a natural state. In short, the River has been significantly modified through irrigation and flood control dams, channelization, river flow containment dykes, riparian habitat loss, water extraction and urban development. According to the Outdoor Recreation of British Columbia it is the 10th most endangered river in British Columbia.

Vaseux Lake was traumatically altered as a result of the Channelization. Confining the river to a single straight channel from Okanagan Falls to Vaseux Lake eliminated the natural flood plains, reduced the length of the river and increased water flow. This has resulted in the River acting as a sling shot for the sill from Shuttleworth Creek, just south of the Okanagan Falls dam, to be directly deposited into Vaseux Lake causing an unprecedented degree of siltation at the north end of Vaseux Lake. Five aerial photographs of the north end of Vaseux from 1967 to 2020 (see attached) clearly show how the mouth of the north end of Vaseux Lake was dredged in the 60’s and the subsequent siltation when the dredging stopped. While a sediment pond was created at the mouth ofShuttleworth Creek, dredging of this pond stopped in the late 1990’s and only began again after the VLSA and the Okanagan Nations Alliance convinced the BC Government to renew its dredging of Shuttleworth Creek after it had failed to do so for approximately 15 years.

Unfortunately, this was not completely successful in diminishing the amount of sitt entering Vaseux as the Shuttleworth Creek sediment pond is simply too small.

The purpose of the project is to assess the effect of channelizatlon and damming on the rapid accumulation of sedimentation at the north end ofVaseux Lake and to determine what remedial steps can be taken to alleviate this dramatic change to the natural hydrological flow. VLSA would like to retain a Water Management Expert to explore various mitigation strategies to reduce sedimentation ofVaseux and bring back the river ecosystem into a more natural state. The study will also look at how the present silt build up at the north end of the Lake is obstructing water flow during spring runoff causing the Ministry of Lands, Forest and Natural Resources to raise the level of the Lake to try and move the same amount of water through the Lake. In 3 of the last 5 years, the Ministry has raised Vaseux Lake to record levels in trying to move water out of Okanagan Lake during spring runoff.

The damming and channelization of river systems have proven to have serious consequences on both fish and wildlife habitat. The biological effects of altering the Okanagan River have never been monitored but in other channelized systems, fish populations have been reduced by 80% (Wesche 1985). Proper mitigation needs to be put in place if Vaseux Lake is simply to be used as a conduit for water flow for other Okanagan Basin priorities. Based on the latest aerial photos, approximately 10% of the Lake has already been lost due to siltation and another 10% is In jeopardy.

It is anticipated that the total cost of the report will be $30,500 plus taxes. VLSA has raised $2000 for this report.

To learn all the details of the Agreement, please access the full report at 20210208_AGR_Contribution.