Water managers hope a federal decision not to declare a type of mussel to be endangered will allow for the full return of roto-tilling to control Eurasian milfoil. The slimy lake weeds, shown here being hauled out of the Kelowna Yacht Club basin in a 2014 file photo, make swimming unpleasant and diminish water quality.

A type of mussel found in Okanagan Lake will not be declared by the federal government to be endangered.

Local water managers hope the decision paves the way for a full return of the rototilling of Eurasian milfoil, slimy lake weeds that harm the ecosystem and make swimming unpleasant.

"We're very pleased with this decision of the federal government," Anna Warwick Sears of the Okanagan Basin Water Board said Thursday.

"It's a step forward, but the full return of roto-tilling will still depend on the provincial government changing their regulations," Sears said.

If the feds had decided to declare the Rocky Mountain ridged mussel to be endangered, that would likely have led to the complete cessation of milfoil roto-tilling. The practice, which involves the weeds being yanked out by their roots by a mechanical harvester during the winter, has been used since the 1970s.

Last year, the provincial government began prohibiting the OBWB from roto-tilling the weeds in areas where the mussel has been found. Bans now exist at the north end of Okanagan Lake, in areas of West Kelowna and Summerland, and part of Osoyoos Lake.

Local officials have been concerned the ever-wider implementation of roto-tilling bans could see milfoil spread back to the kind of extensive conditions that existed decades ago. That could cause serious harm to the Valley's tourist industry, they say, as well as significantly degrade the aquatic ecosystem.

The OBWB and Valley politicians say the provincial government has never presented solid evidence that roto-tilling imperils the mussel. To the contrary, they say, it's likely that the mussel would be among the many aquatic species that could be jeopardized by a widespread resurgence of milfoil in Valley lakes.

Yesterday, the federal government said more study is needed before the mussel can be reclassified as a "species of special concern" to an endangered species.

"Additional consideration on potential reclassification of the Rockey Mountain ridged mussel will be done, and this will also take into account socio-economic impacts and effects on the broader Okanagan Basin system," Minister of Fisheries Jonathan Wilkinson said in a release.

Kelowna-Lake Country Liberal MP Stephen Fuhr said there were "too many unanswered questions" for the mussel to be declared to be endangered.

"Such (a declaration) could have the potential to make it difficult to control Eurasian watermilfoil, an invasive species that has the potential to wreak havoc in our beautiful local lakes," Fuhr said in the government release.

In Canada, the Rocky Mountain ridged mussel only exists in the Okangan basin, but it is found in many parts of the U.S.