The federal government has put a halt to exploration activities slated to be carried out in connection with the controversial proposed New Prosperity mine near Williams Lake, B.C.

The latest activities were given the go-ahead with the issuance of permits by the B.C. Liberal government in its last few days in power.

In a letter dated July 28 and released by the Tsilhqot'in Nation the same day, the Canadian Environmental Assessment Agency (CEAA) informed John McManus, the chief operating officer of Vancouver-based Taseko Mines Ltd., that its proposed activities "may cause an environmental effect...[and] are subject to the prohibitions of CEAA 2012 [the Canadian Environmental Assessment Act]."

The move by the B.C. Ministry of Mines and Energy to grant the permits on July 14—which would have allowed activities such as hundreds of drill holes and test pits, as well as the construction of almost 100 kilometres of seismic lines and new or modified trails—caused outrage from critics of the proposed mine, which had twice been turned down by federal regulators, in 2010 and 2014.

The B.C. NDP/Green Party of B.C. coalition government assumed power on July 18 under the leadership of new premier John Horgan.

Joe Alphonse, Tsilqot'in chief and tribal chair, said in a July 17 news release that the permits were "a typical move by the Liberal government. They are a dead political party trying to mount a dead horse and hoping to ride it to a comeback." 

The CEAA issued the cease-and-desist order after receiving a "notice of work" letter from Taseko describing the planned exploration work to be done at the site, which is approximately 125 kilometres southwest of Williams Lake and which contains Fish Lake, a body of water with special significance to the Tsilqot'in Nation, which calls it Teztan Biny.

Fish Lake, home to an estimated 85,000 rainbow trout, was slated to become the mine's impoundment dump for toxic tailings.

The CEAA letter—from Kristin Coverley, the agency's senior compliance-enforcement officer—warned that "the Agency may consider conducting an inspection of the site of the proposed activities, in order to determine if any activities have occurred in connection to the designated project".

The letter also warned: "Each day an alleged violation...occurs constitutes a separate offence."