Some Okanagan beaches left in the weeds because of protected mussels

You may notice more weeds at some Okanagan beaches this summer since the Okanagan Basin Water Board doesn't have a permit to rototill in areas where Rocky Mountain Ridged Mussels have been discovered.

For the past 40 years, it has treated the invasive lake weed, Eurasian Water Milfoil, by rototilling it in the winter and harvesting it in the summer, said James Littely, operations and grants manager for the OKanagan Basin Water Board. 

There is now concern that this work could harm the mussels.

"I would expect this to be a pretty weedy year, because we lost the entire season of rototilling in those areas where the mussels were identified," said Littely.

Rocky Mountain Ridged Mussels

Provincial biologist Lora Nield said the Rocky Mountain Ridged Mussels they have found in Canada have very low populations and are very isolated.

The Species at Risk Act lists these mussels as a special concern, and the province is trying to have their status upgraded to endangered. 

"There's a responsibility for all British Columbians to help protect and preserve these species. Mussels themselves are an important part of the ecosystem," Nield told Radio West host Sarah Penton.

When populations of this species of mussels are discovered, a 100-metre buffer zone is put in place where treatment of weeds needs to be modified. 

"In this case, specific to the rototilling of milfoil, we will be looking at modifying the approach to treatment at these sites to the harvesting method, which is much less of an impact to the Rocky Mountain Ridge Mussel," said Nield.

"There's always a balance between trying to manage for the recreational use and the values at the site and the natural environment which is what makes ... the Okanagan what it is."

Milfoil 

The water board is concerned that not rototilling milfoil could mean losing spots to swim, clogged boat motors and higher chances for toxic blue-green algae blooms.

If left untouched, the weeds can get so dense they create thick mats that can grow to the surface of the water, said Littely.

"It encourages waterfowl to sit on top of them and then they defecate in the water creating poor water quality conditions."

Even with harvesting, the weeds can still spread through fragmentation. 

"Especially when they go dormant in the winter, they break off and you end up with big piles of weed in the winter and then they turn into mud and they change the entire beach area and under the water," said Littely.

Beaches affected 

Kin Beach in Vernon is one of the beaches that will be most affected by milfoil, he said. 

Half of the beach was restricted from rototilling five years ago and now that's been extended to the entire beach.

Other beaches impacted include the Casa Loma area in West Kelowna, most of the foreshore along Summerland, parts of Skaha Lake and the entire north end of Osoyoos lake, said Littely.

Waiting for a permit

The Okanagan Basin Water Board has been asked by the province to get a federal permit that takes the mussels into consideration and to provide additional documents to help inform the provincial permit, said Littely.

The province and the water board will be doing a study to determine whether milfoil could harm mussels. 

"Unlike other work in the water, we're only targeting this one species of negative invasive weed. So, it might be more beneficial for us to actually continue our 40-year-old rototilling program than to let the weeds propagate," said Littely.