Ausable Freshwater Center

WILMINGTON — One of the most iconic species in the Olympic Region is facing a myriad of environmental threats to its populations.

The brook trout, fish species native to the region that thrives in cold well-oxygenated water, has seen its population decline throughout the state as climate change warms water bodies and, in some instances, reduces oxygenation in lakes by impacting turnover between warm and cold seasons.

With a diminishing amount of viable habitat, much of which — namely a warming planet — is far beyond the control of wildlife management groups, attention has turned to preserving habitat in pockets that scientists hope will remain sufficiently cold enough to continue supporting brook trout populations well into the future.

Fortunately, the Adirondacks, and specifically higher-elevation areas in and around the High Peaks region, are one of those.

The AuSable River, in particular, is considered a prime brook trout habitat for its durable resilience to climate change — due in large part to its ample forest shading and much of its water draining from high mountain slopes, both of which combine to keep the river’s waters relatively cooler and relatively more resistant to a warming climate.

Photo by Chris Gaige Ausable Freshwater Center Stream Restoration Manager Gary Henry and Executive Director Kelley Tucker at the organization's new headquarters in Wilmington on Monday, Dec. 16.

The river is frequently stocked with brook trout. Despite a suitable climate profile, brook trout in the river face another threat that has, up until this point, received comparatively little attention: an uptick in sedimentation.

The Ausable Freshwater Center (formerly the Ausable River Association) is a non-profit scientific organization that studies the AuSable River watershed and advocates for a variety of projects and practices throughout the watershed aimed at protecting the water quality and the ecosystem that depends on it.

The organization embarked on a mission to better understand the sources for the sediment, how it is harming brook trout and other river species and if there were any actions that could be taken to mitigate the issue. Gary Henry is one of the organization’s staff members who is leading the sediment sources identification project along the West Branch of the AuSable River- among a myriad of other projects he is working on in the watershed.

The West Branch Sediment Study

“What we want to understand is where this (sediment) is coming from and can anything be done about it,” he said. “Is the source in wilderness areas, where we can’t necessarily work, or is there something we could do to maybe intercept this sediment somewhere? Are there projects that could be implemented on private land that could just stop this stuff from moving downstream? That’s kind of our first step here.”

Marcy Dam might be a possible culprit of sediment in the West Branch, according to Henry. Although he emphasized that further research has to be done to conclusively show that is the case, he said there is circumstantial evidence to support its suspect status. The now former dam — located in the High Peaks Wilderness area was built along Marcy Brook, a tributary to the West Branch of the Ausable River. Marcy Dam was blown out during the torrential rains from Hurricane Irene in 2011.

“That was a dam that existed for a long time,” he said. That was an impoundment. … Rivers and streams move sediment. So, sediment fills in behind it, and when you remove the impoundment, that sediment can start moving again.”

Henry said the study seeks to find other possible sources of sediment in the West Branch’s tributaries.

“No one has really looked at this,” he said. “Maybe there were impoundments that we didn’t know about — dams like Marcy that blew out in Irene, for example.”

Henry said even if the smoking gun isn’t found, being able to cross certain tributaries “off the list” as sources of sediment is equally as important when it comes to understanding the problem.

Sediments impacts

Henry said sediment impacts the river by filling in and eliminating deep pools in the water. These pools are important for the river’s ecosystem, as they help to cool the water.

“In the West Branch and the East Branch (of the AuSable River), good habitat looks like short riffles to re-oxygenate the water and deep pools to chill the water,” he said. “In the deeper pools, there are more exchanges with groundwater, so the water is colder, and healthy (tree) canopies are shading the river and keeping it cooler by preventing the sun from its dark surface – which would otherwise warm easier.”

Henry said the Ausable Freshwater Center’s West Branch sediment sources identification project was informed by first-hand sources.

“In the west branch, we have a lot of contacts with the fishing guides and the angler community,” he said. “They’ve been telling us over the past decade that pools have been filling in with sediment.”

Henry said these pools are critical for brook trout habitat, as well as small macroinvertebrate bugs that make up the base of the food chain for fish in the river.

“When the (bugs) go away, the food chain collapses,” he said.

Using LiDAR as a tool   

Light detection and ranging (LiDAR) data refer to high-resolution digital elevation models that are collected from an aircraft using sensors that beam light down to Earth’s surface. That light is then reflected back to the sensor, and the amount of that it takes to return to the sensors — a proxy for the distance it has traveled — is used to map the elevation of Earth’s surface, given that points of higher elevation are physically closer to the aircraft.

“It’s basically a digital representation of the topography of the landscape,” Henry said. He noted that the finished product is akin to pixels in an image. The LiDAR map is composed of grids, each grid having an individual number — and in some representations, a corresponding color — that when taken together gives viewers an understanding of the land’s contours.

He said he first began working with LiDAR data in graduate school in 2000, and the technology — as a result of advances in sensor quality and computer processing power – has made massive advances in resolution quality since then.

“Geomorphologists are in heaven with this type of stuff,” he said. “I was using data with 30-meter resolution. Now, it’s nothing to get 1-meter resolution.”

Henry said that the data can be used to understand sediment sources by comparing, over time, how landscapes along rivers have changed. He said the computer does all of the work, and produces what is called a “digital elevation model of difference.”

“You’ll get valuable data there,” he said. “You’ll be able to see which streams are experiencing slope failures and erosion through the river corridor. You’ll also see any fans that might have developed in those channels and things like that.”

Henry said that elevations that have decreased overtime along a river are likely sources of sediment, as the earth ground that was lost was likely carried away by the river. He said the part of the grant funding that the Ausable Freshwater Center received will be used to gather new mappings of river landscapes.

The organization was one of a dozen local groups that recently received funding from the Local Enhancement and Advancement Fund (LEAF) program, The grants are funded by revenue from the 5% occupancy tax collected by Essex County. The Ausable Freshwater Center received a $25,000 award.

The LEAF grant is a portion of the overall funding for the West Branch Sediment Study. Henry said that they have received a total of about $300,000 for the project, much of it coming from state sources of funding. He said the Ausable Freshwater Center is close to raising its $325,000 goal to support the project, with ongoing efforts to secure the remainder.

Henry said he expects fieldwork for the sediment study to begin this upcoming summer. He said the LiDAR data will be gathered using a fixed-wing aircraft, but must be gathered in a narrow window of time when the deciduous trees have lost their leaves but before there is snow on the ground.

He said he expects findings from the study to be available in about two years from now.

Henry’s background

Henry has served as the Ausable Freshwater Center’s stream restoration manager since 2020. A geologist, Henry earned a bachelor’s degree from Kent State University, in Ohio, and holds a master’s degree from Baylor University, in Texas.

His graduate studies focused on fluvial geomorphology, a specialized field that studies how physical processes, both human and naturally-caused, impact and shape rivers, as well as their surrounding areas.

Henry brought a combination of industry and academic experience to the Ausable Freshwater Center. He worked as a hydrogeologist at an environmental engineering firm after completing graduate school. He said a lot of his work there focused on rapidly-urbanizing streams in the Dallas-Fort Worth area.

His work focused on soil and groundwater remediation efforts, with cleanups taking place around gas stations or old industrial sites in the area. In 2009, he moved to northern New York to pursue a new, and different, opportunity.

“I took a complete 180-turn career wise and decided to go into academics,” he said. Henry was hired by Clinton Community College, where he taught until he joined the Ausable Freshwater Center.

“I’m not going to lie, having summers off and that nice long break around Christmas time was pretty nice,” he said. Henry, who grew up in rural Ohio said he and his wife also wanted to move back to a bucolic place after having spent a significant amount of time living in Dallas.

Henry said his background in industry and teaching prepared him well for his position at the Ausable Freshwater Center, where his work is a combination of scientific research, data-driven conversations with a wide array of stakeholders to gather feedback on watershed remediation projects, and ultimately advocating for and implementing those projects.

“My work centers around finding ways that we can bring habitat back, protect infrastructure and improve flood resistance – and do all of that in a smart way,” he said.

Henry said even after extensive human manipulation, river ecosystems can “sort themselves out” and correct naturally. The rub, he said, is when those rivers are surrounded by infrastructure and development that is in place for the foreseeable future, such as the communities and roads along the AuSable River. He said this creates a balancing act between protecting habitat and protecting development along the river, emphasizing that the two are often not mutually exclusive.

For more information on the Ausable Freshwater Center, including information on past projects throughout the Olympic Region that the group has completed, visit ausableriver.org.