Getting rid of milfoil in Vaseux Lake is a lot easier said than done.
According to a report by James Littley from the Okanagan Basin Water Board, rototilling the lake for the first time could create other problems.
“It also has the potential to create larger impacts to human health and fish, and could potentially have drastic impacts on the health of Osoyoos Lake downstream.”
In summer 2016, residents of Vaseux Lake requested that the board start treating milfoil in the lake.
The proposed work area covers 67 hectares, which is equivalent to almost 24 per cent of the total surface area of the lake.
At that time Littley advised the residents that rototilling would be the best option for long-term treatment, which was to begin next month.
But a number of issues have come up. For example, Vaseux Lake is a migratory bird reserve, with a no-motors restriction on the lake. A federal permit from Environment and Climate Change Canada was issued in November 2016 to allow milfoil control, but the water board requires a permit to conduct work in and around a stream under the B.C. Water Sustainability Act.
Littley said there is no boat launch large enough to accommodate their machines around the lake. The regional district has been trying to identify a suitable location.
The other issue is First Nations fisheries and cultural/archeological considerations.
This summer Littley met with Okanagan Nation Alliance (ONA) and the Osoyoos Indian Band to discuss concerns around the effect that rototilling and milfoil removal may have on fisheries work.
“At that meeting I was also made aware that there may be cultural/archeological sites in or around the lake, which pre-date the building of McIntyre Dam, and the channelization of the river,” Littley said.
He noted that $5,000 was set aside to offset the costs for ONA staff to create a work plan to identify and address concerns.
Since Vaseux Lake has never been rototilled in the past, it is unknown what may be released from the sediment of this shallow, small lake, and what potential effect it could have on water quality and the ecosystem, Littley said.
He noted that Dr. Jeff Curtis from UBC of the Okanagan has indicated there is potential for release of lead, arsenic, nitrate and phosphorus, as well as other substances, which could lead to toxic bacteria and algae growth affecting Vaseux, the Okanagan River downstream, and the health of Osoyoos Lake.