Heavy rainfall since Tuesday has made the land around a toxic mining tailings pond near Salmo, B.C., unstable.

Water has saturated the retaining walls of an old Hudson's Bay zinc tailings pond and those walls are now falling apart.

"We're very concerned that there is an instability to the whole thing," said Jim Gustafson, the chief administrative officer with the Regional District of Central Kootenay.

"There is moisture that is coming out of the dam — so much so that [Tuesday] night, if there was a break, this flow of water would go down the hill and cross Highway 3."

Officials worry the toxic water could also spill into nearby rivers and drinking water.

The mine was decomissioned 30 years ago. The tailings pond is now owned by the regional district and is part of their landfill.

Officials are trying to pump out the water, and hope dry weather in the forecast for Wednesday will allow them to reinforce the walls so the dam does not give way completely.

Current provincial flood watches, warnings and advisories:

Northern Interior (Skeena, Omineca, Peace)

  • Stuart River and Stuart Lake – flood watch.
  • Nechako River near Prince George – high streamflow advisory.

Southern Interior (Cariboo, Thompson, Okanagan, Kootenay)

  • Shuswap Lake – flood warning.
  • South Thompson River – flood watch.
  • Shuswap River at Mabel Lake and downstream (including around Enderby) – flood watch.
  • Thompson River (including Kamloops area and Kamloops Lake) – high streamflow advisory.
  • Nicola River below Nicola Lake to Merritt – high streamflow advisory.
  • West Kootenay – high streamflow advisory.
  • East Okanagan (including Mission Creek) – high streamflow advisory.

Meanwhile, the heavy rain caused problems throughout the Kootenay region, where local states of emergency were declared in areas around Creston, Ymir and the Slocan Valley.

Last month was the rainiest June on record in much of the southern Interior of B.C., according to meteorologist Ron Lakeman.

The most precipitation fell in the West Kootenay, where the weather station in Castlegar recorded 227 millimetres of rain, nearly doubling the old June record of 117 millimetres.

"It was phenomenally wet. It is typical for June to have a number of weather systems to come through with significant precipitation, but this June it was almost an endless procession of systems," said Lakeman.

Kelowna, Penticton and much of the East Kootenay also broke records. In Nelson, it was so wet officials cancelled Canada Day fireworks and in Castlegar the entire birthday celebration was postponed because of rain.

Doug Lundquist with Environment Canada says June is generally rainy in the Interior, but this was exceptional.

"We do have our monsoonal season. We tend to get thunderstorms in early summer and we can get extensive rain. It was June on steroids for sure."

Much of northern B.C. and the South Coast also got a lot of rain in June, but not record-setting amounts, he says.

But Lundquist says it's over now and he is forecasting a transition into more seasonal summer sunshine and heat.

Several Fraser Valley communities lifted evacuations alerts for unprotected areas along the banks of the Lower Fraser River on Tuesday, saying the water level is receding and the fear of flooding is over.