News Leader News for August 7, 2007
SIMILCO LANDSLIDE CREATES DOWNSTREAM CONCERN
The Okanogan County Sheriff's Department says the landslide that blocked the Similkameen River at the former Similco Mines site was first noted at 11:00 PM on Wednesday, August 1st.
An unidentified camper along the river had reported the level of the river had dropped sharply near Princeton "consistent with a landslide blockage."
Local residents noticed the low river the following morning and alerted a variety of agencies about their concern and that "the flows then spiked back up at 9:00 AM."
Eyewitnesses told the News Leader that suddenly the river climbed between three and four feet in height and the water had changed from a crystal clear colour to what was described as either 'chocolate milk' or 'coffee with cream' brown.
As the morning passed and the river level stabilized there were stories that there had been a breach or collapse of a dam wall at the massive tailings pond named Smelter Lake, about 15 kilometres upstream from Princeton on property formerly owned and mined by Similco Mines.
The Okanogan County Sheriff's Department says a helicopter reconnaissance flight from Penticton at 12:30 PM was scheduled by officials on the Canadian side of the border and an hour later had located and photographed the slide site.
"Their report stated their priorities were to monitor river levels downstream and assess the stability of the slope above the slide site.²
By mid-afternoon the Washington State Emergency Operations Centre (EOC) contacted Okanogan Emergency Management Department and based on the information they had at the time "it was felt that the only danger was muddy water."
Within the hour the Oroville Irrigation District contacted OEMD with concerns of "a surge of water coming down the Similkameen" as there were 12 to 24 miners in the river.
"This information made the situation significantly more serious, threatening the safety of people who would be directly in harms way," stated the Sheriff's Department.
OEMD investigated further and following contact with an unidentified Canadian agency discovered there had actually been a landslide at the former Similco Mines site and that the river had been blocked for nine hours, then the blockage was breached allowing a surge of water to be released.
Water flow data released at the time indicated normal flow was measured at 300 cubic feet per second (cfs), with it dropping down to 60 cfs when the river was blocked and with a peak flow after breaching the blockage measuring 1,350 cfs.
OEMD was told, "The site of the blockage was a tailings disposal dump site, and there were possibly lots of tailings in the muddy water headed downstream."
The Emergency Management Department was then unable to obtain further information from 'the Canadians' regarding the volume or size of the surge and when it would cross the border into the United States.
Based on that, the Sheriff and Chief Deputy dispatched deputies to the scene of the river to begin immediate evacuation of any miners in the Similkameen between Nighthawk and Oroville.
As the miners are required to be at least 60 metres apart, it meant a search of the entire length of that stretch of the river.
By 3:00 PM Oroville Police Department became the incident staging command centre and an evacuation of anyone in the river between Nighthawk and Oroville was implemented.
"No persons living along the river were asked to leave or evacuated," says the Sheriff's Department.
"This action was taken as a precaution due to not knowing the degree of the surge, if any."
The evacuation was made possible with cooperation from Okanogan Sheriff deputies, Oroville Police, Tonasket Police and US Border Patrol.
Based on a lack of information OEMD contacted the National Weather Service in Spokane who in turn contacted the River Forecast Centre in Portland, Oregon to determine the size of the surge and estimated time of arrival at the US Border.
"The NWS was extremely helpful, and stated at the most, the surge would probably be only about a foot, and possibly not at all due to the attenuation of the flow along the river from Princeton."
The Oroville Fish Hatchery was advised to close their inputs from the Similkameen River "in case the materials coming down the river were contaminated."
It wasn't until late in the afternoon that the Regional District Okanagan-Similkameen released information on what they had identified as a landslide.
"Staff from the RDOS, the Town of Princeton and Ministry of Environment responded to reports of the water level in the Similkameen River dropping rapidly to ensure there was no public safety threat," says RDOS Board Chair Dan Ashton.
"It was discovered that a landslide had occurred in an isolated area approximately 14-kilometres south of Princeton."
Ashton says the river dropped when the slide held back the regular water flow then eventually released it sending a higher volume of water downstream along with muddy water.
The RDOS advised at the time that while the Similkameen River remained muddy from the debris they recommended, "residents and recreational users along the river to take precautions if in the water."
At 5:30 PM OEMD were contacted by 'Canadian officials' that the surge was at Wolfe Creek, about 15 kilometres East of Princeton and that at "the present rate, muddy water only would arrive at the US border" based on a helicopter survey.
"Canadian personnel did not have any solid information on possible hazardous content of the flow, but stated they did not think there was any danger," says the Sheriff's Department.
Based on this information OEMD determined there was no immediate danger and a surge of water that would threaten life or property would not be coming.
"The only remaining threat was the possible hazardous nature of the materials in the flow coming from the landslide," they said.
"The Canadians were asked for any report on water quality, but did not provide any information."
Within the hour the Oroville incident command structure and incident command post were demobilized.
By that evening, the silt cloud had travelled as far as a kilometre short of the Sterling Creek Bridge, about 25 kilometres East of Princeton.
Okanogan County Sheriff Frank Rogers indicated that officials from the Department of Ecology arrived in Oroville during the evening and were going to stay in the area to "monitor water quality to make sure there are not toxic materials in the water."
The following morning, August 3rd, the river had just about cleared up completely in the Princeton area.
"They're estimating 5 kilometres per hour as far as the float time," Dennis Walker of Giant-FM said that morning.
"That's what some locals have told me today."
Alan Thom, interviewed by Walker agreed on air at the estimated speed and speculated on the arrival in Keremeos.
"It's about 70K from here to Princeton - 75K, something like that, and you figure the river winds back and forth so sometime later this morning or early this afternoon."
The cloud made it's way downstream reaching the Red Bridge near Keremeos at 1:00 PM.
By Saturday, August 4th, the water at Bromley Rock had cleared up considerably although it still had a slight cloudy appearance.
The silt cloud spent most of the weekend in the Keremeos area moving slowly downstream.
