Contractors for Trout Unlimited and federal agencies cooperating on a project to restore fisheries habitat in the Yankee Fork of the Salmon River disturbed groundwater and released fine clay sediments into the stream on June 26.

That created a muddy plume of water which flowed down the Yankee Fork into the Main Salmon River where high water diluted the plume. The excavation work was going on outside the stream channel. The muddy water concerned area residents, including Brant Tritthart of Challis and Rep. Dorothy Moon, who wondered why a project designed to improve fish habitat and water quality was allowed to create a potential problem for fish and the recreating public.

Tritthart is site manager for Hecla’s mothballed Grouse Creek gold mine in the Yankee Fork drainage. He said he could not speak for the mining company, but could only express his concerns as a private citizen and a person with experience in the mining industry.

“Dorothy Moon and I feel they need to be responsible and held to the same standards as mining companies,” Tritthart said. A mining company probably would have been fined and issued a cease and desist order if it had stirred up the stream, he said. There’s lots of groundwater there,” in the Yankee Fork drainage, their engineers should be on top of it to keep it (siltation) from happening. If you can’t protect what we have now, why do the project?”

Moon, who co-owns a private mine in the Yankee Fork drainage and lives up Jordan Creek, agreed.

“We didn’t have a rainstorm here yesterday,” Moon said the day after the plume was discovered, so a natural event couldn’t have caused the silty plume. “If someone else had put that sediment into the river, they’d never hear the end of it. I don’t think it’s fair. We’re all equal under the law.”

Hecla employees took photos of the muddy plume and showed them to Tritthart, who spoke with Moon and notified a water quality manager with the Idaho Department of Environmental Quality. Tritthart and his wife Lynn emailed the photos to Moon, IDEQ and The Messenger.

Moon notified Dustin Miller, director of the Idaho Department of Lands, and Scott Pugrud, director of the Governor’s Office of Species Conservation.

Tritthart expressed concern that the muddy plume might contain mercury, which was used in historic mining to extract gold from ore. Some was spilled and probably buried in the Yankee Fork Dredge piles.

Last week’s release of sediment was unanticipated, Jim Gregory and Cassi Wood, co-project managers for the Yankee Fork restoration project, said. As soon as it began, they stopped excavating and took measures to stop the plume. They were not required to have any sediment or mercury monitoring equipment in place because no release was anticipated.

While excavating the dredge piles, Trout Unlimited project managers have monitored to see if any methyl mercury vapor is released into the air, Wood said. So far, they have detected no release above natural background levels, which are essentially zero.

The Yankee Fork Dredge mined gold in the stream channel between 1940 and 1952, basically turning the rocks and salmon spawning gravels of the streambed upside down, straightening the channel and wiping out pools where fish could rest. Some artificial ponds were created for the fishing public among the dredge piles, off the main channel years ago, Wood said. A few years ago, the Yankee Fork restoration project reconnected those ponds to the Yankee Fork by constructing side channels. Sediment in the ponds tested negative for methyl mercury, Wood said, which is where the heavy metal was most likely to settle and end up.

Wood notified DEQ, the Bonneville Power Administration and NOAA Fisheries, which oversee the project’s discharge permit.

The discharge permit now allows Trout Unlimited to put excavators into the stream channel between July 8 and Aug. 16, Wood said. That window falls after steelhead fry have emerged from stream gravels and before Chinook salmon start spawning. It protects the fish from sediment releases, which are unavoidable while doing in-stream work.

Because last week’s work was not in the stream channel, Wood and Gregory said, the sediment release was unexpected. The excavator was digging what will become a new stream channel 50 feet from the flowing water and nearly 850 feet above where the silty groundwater surfaced and flowed into the Yankee Fork.

This season’s Yankee Fork restoration project started June 24, with an excavator digging the new stream channel for the Yankee Fork that will more closely resemble a natural stream, Wood and Gregory said. They didn’t count on the groundwater being so shallow on the downstream edge of their project near the ghost town of Bonanza, but they hit groundwater and stirred it up and the silty subsurface water flowed underground for about 850 feet from the hole they’d excavated into the river.

The crew immediately stopped work and took action to stop the muddy underground flow, Gregory said. They started pumping the silty water out of the hole and into a water tanker truck, which hauled the muddy water away from the stream channel and dumped it on the uplands.

It’s very unusual that silty groundwater is still silty when it flows into the river 850 feet downstream, said Wood. It wouldn’t have happened in a normal stream channel. Normally, soil and organic matter act as a natural filter and clean groundwater. But the area where the dredge operated is not a normal stream, she said. Groundwater there flows through cobble-sized rock and pockets of sand that can divert underground flows. The spaces between the cobbles don’t have any of the filtering organic matter that normal soils do, so the groundwater stayed muddy all the way to the river.

The Yankee Fork restoration project, Trout Unlimited and cooperating agencies have a permit for in-stream work, where siltation problems normally occur, said Tom Ford, natural resources staff officer for the Salmon-Challis National Forest. The excavator was working on dry land, and muddying up the groundwater and the Yankee Fork was unpredicted, Ford said. However, “we will treat that site as if it were in-stream work,” he said. That means restricting excavation to the July 8 to Aug. 16 window.

“Our permit allows turbidity during that period,” Wood said, but if it exceeds standards, work is shut down. In-stream excavation work can create turbidity for two hours, but at four hours, if silty water is still being put into the stream, all work must stop. TU is adhering to those same standards for the current off-stream channel work, she said.

“Trout Unlimited is choosing to comply (with standards) as if this was in-stream channel work,” said Ford.

The site where the new stream channel is being dug is on land owned by Simplot Corp., Ford said.

“The bottom line on this is, we do cause some temporary impacts to fish,” Gregory said. “Ultimately, the thing we’re doing is making it better for them. I like to tell people we’re giving birth to a stream out there and there’s going to be some blood, but we don’t want the patient to die.”

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