June 19 update from the Okanagan Basin Water Board (OBWB) regarding Milfoil harvesting at Solana Bay on Osoyoos Lake

Thank you for offering to post some information about milfoil control operations in Solana Bay.

First the good news. The harvesting machine is currently being assembled at the Osoyoos Marina, and will be launched today, immediately moving to Solana Bay as a priority area. We will begin by cutting a navigation channel around the perimeter of the bay and down the center of Solana Key.

This work will happen over the next few days, and I’d ask that residents don’t try to flag down the operator, as it will only make the whole process longer, and less will get done by disturbing him.

There are also safety reasons that people should not flag down the machine, both for their own safety, and the safety of our operator. I’d also ask boaters to slow down whenever they are around our machines, since we have flat-bottomed hulls, and are very susceptible to wake and waves.

Now for more detailed information. The OBWB controls milfoil in all the major valley lakes, including Okanagan, Kalamalka, Wood, Skaha and Osoyoos.

We only have three full time staff to control all the milfoil in those lakes, and we work throughout the year on this one objective.

During the winter, between October and April, we rototill the lake bottom to remove the milfoil roots while the plant is dormant. Those weeds float to the surface, and die in the cold temperatures. Rototilling reduces the overall volume of weeds in an area, and if done in consecutive years, it can temporarily eliminate milfoil.

However, it also provides room for native weeds to grow back, so it only targets the invasive plants, and does not always mean a plant-free area. We are not allowed to target native plants which are beneficial to water quality and the ecosystem.

During the summer, we harvest the weeds, which involves cutting the plant about 5-6 feet below the surface, and conveying it onto our machine. The load is then dumped on shore, and a truck collects the weeds and takes them to farms, gardens or orchards if requested, and in the worst case, to the landfill.

There are only two harvesting machines for all the lakes in the valley, so no place gets cut more than once per summer. Milfoil grows up to 5 cm per day, so if it is cut 6 feet down on June 20th, it could reach the surface again by about July 26th.

Once the machine leaves Osoyoos Lake, it moves into Skaha and Okanagan Lake, while our other Machine starts in Wood Lake, and moves into Kalamalka and north Okanagan Lake.

In Solana Bay specifically, in the last five years, we have been restricted by our environmental permits to rototilling only between April 1st and October 1st, which is outside of the optimal time.

This year, we intended to rototill the bay after April 1st, but because of the flooding, we had to remove the machine before we could get into the bay (so our operator volunteered to help sandbag instead).

We also face other challenges:

-when the lake freezes in the winter, we have to pull our machines out before they get stuck in the ice;
-when the lake is too high, we cannot physically fit under the highway bridge;
-when the lake is too low, we cannot physically launch or remove our machines at the marina launch;
-any hazards in the water, such as mooring buoys, anchors, docks, barges, boats, airplanes, swimmers etc make us less efficient, or can even completely exclude us from those areas.
-there is a lack of feasible weed transfer sites for our harvesting operations in the summer, and the nearest to Solana Bay that accommodates both the machine from the water, and the truck from land is at Legion Beach, which adds hours of transport time each day.

The Town of Osoyoos works with us to accommodate our operational needs as much as they can, and we try to be responsive to the areas that have the worst growth each year.

As a policy we treat public beaches, parks, and boat launches as a priority. The service is provided to all residents at public parks and beaches, not only to those who own lake front property, or a private dock. We also treat areas of the lakes that are adjacent to private property once the public areas are treated, and as time allows.

People can find more information on our website at http://www.obwb.ca/milfoil/

Finally, if anyone is willing and has space available to take a dump truck load of milfoil, which can be used for enhancing compost, please contact me.

Once again Birgit, thank you for helping to spread the right information, and for all the work that the Osoyoos Lake Water Quality Society does for the people of Osoyoos.

K. James Littley, C.D., M.A. — Operations and Grants Manager, Okanagan Basin Water Board
1450 KLO Road, Kelowna, BC V1W 3Z4
Office: 250.469.6270