The green group uses certified logging methods designed to protect rivers and other sensitive ecosystems.
But a landowner in Essex County is accusing the Conservancy's tree-cutters of damaging a certified trout stream.
As Brian Mann reports, state officials have opened an investigation.
Dan Snyder trudges on snowshoes through mushy spring snow on his land in North Hudson. He comes to a small stream that looks chocolate brown.
"It was never like this during spring runoff. It's completely muddy, silt, and I can't imagine any trout being able to survive in this. And it's completely heartbreaking to me."
Snyder walks on to the edge of his property and points to land on the other side owned by the Adirondack Nature Conservancy. This tract is part of the former Finch Pruyn timber land.
"I'm looking at like, to an untrained eye, it's kind of looks like a hurricane went through it. Trees knocked down, slash left, as well as a downward grade where the skidder trails went, a tremendous amount of erosion just from the beginning."
The Nature Conservancy is an environmental group, but it also operates one of the largest expanses of timber land in the Park. Their forests supply logs to the Finch paper mill in Glens Falls.
Mike Carr, president of the Conservancy’s Adirondack chapter, now acknowledges that mud from this harvesting site flowed downhill into at least one protected stream.
"It does appear that the warm-up late last week caused a lot of snowmelt and surface water to begin to move and some sedimentation into a tributary," Carr acknowledged.
"Which we immediately moved to mitigate with straw bails in the streams and water bars in the wood road and managed to get things cleared up. It was running completely clear on Sunday. We regret that there was an event late last week and we took very aggressive steps with our forest management team to mitigate them."
The work here was supervised by Leonard Cronin with a company called Finch Forest Management.
That’s a department of Finch Paper based in Glens Falls, which handles the logging on much of the Nature Conservancy’s land.
Cronin says his crews actually exceeded what are called best forest management practices, setting up wide buffer zones designed to protect the streams that cross Snyder’s property.
"With the best management practices, the intent is to minimize siltation in the water bodies, but we all know that we cannot totally eliminate it," he said.
According to Cronin, his crews were taken by surprise by the spate of warm weather last week that triggered a lot of run-off.
"There was a lot of water, snowmelt and water drainage off the job. That was unanticipated."
The Nature Conservancy suspended logging operations at the site last week.
Speaking on Friday, Snyder said the work continued long after warmer weather had arrived and the snow began to melt.
"The logging was going on, you know, the saws going, maybe two days ago."
Snyder hired a company called Niche Forestry based in Essex New York to examine the site.
The company’s report, shared with North Country Public Radio, concludes that the Nature Conservancy's logging operation had produced “extreme turbidity” in one trout stream and “abnormal” turbidity in another.
“The negative impacts to the brooks may have been avoided,” the report states, if “the harvesting operations halted prior to spring thawing conditions.”
State officials say an investigator with the Department of Environmental Conservation has been on the site repeatedly over the last week, most recently on Sunday.
In a statement, DEC spokeswoman Lori Severino said officials are working "to address the situation."
Sources with the DEC and the Nature Conservancy say they expect that some form of ticket or notice of violation will be issued, but that hasn’t happened yet.
This incident comes at a sensitive time for the Nature Conservancy.
The group is hoping that this land in North Hudson will be purchased by the state of New York and added to the forest preserve, part of the massive Finch, Pruyn land deal.
Conservancy spokeswoman Connie Prickett says while the green group waits for the state to move on the open space deal, logging will continue.
"We're also very comfortable that the harvesting that is taking place is under two certifications [of quality], the highest sustainable forestry standards that exist anywhere," she said.
If a notice of violation is issued, the Nature Conservancy and Finch Forest Management say it will be the first either of their organizations or contractors have received in the Park.
Neighbor Dan Snyder, meanwhile, says he’s considering filing legal action against the Nature Conservancy for what he describes as damage to the value of his land.