Engineers detail Indian Lake Stone Dam rehab designs 

Project estimated to cost $7.7 million eyed for start later this year

By Zachary Matson

An overhaul of the Indian Lake Stone Dam would modernize its gate operations, mitigate visible water seepage, strengthen its embankment and bring the 126-year-old structure into conformance with state design standards. 

The project, which has been a point of discussion among officials for years, is estimated to cost $7.7 million and could go out for contractor bid by late summer, according to design plans and a construction timeline presented at last week’s Hudson River-Black River Regulating District board meeting. 

The mammoth stone dam was constructed by a consortium of logging companies in 1897 to facilitate log transport on the Indian and Hudson rivers and was last renovated in 1987, around the time ownership transferred to the public benefit corporation charged with flood control. It holds up the 4,225-acre Indian Lake impoundment in the south-central Adirondacks.

A 2014 engineering assessment outlined upgrades needed to align the dam with new Department of Environmental Conservation standards and ensure the structure could withstand the floods of massive storms, ice pressure and other threats to its stability. 

Some local residents have asked the dam be outfitted for hydropower generation as the state seeks more renewable energy production, a process that would require additional design investment, an operator to pursue federal licensing and potentially a state constitutional amendment to allow for that use at the site. Regulating district officials have said they are focused on making necessary safety upgrades and are not pursuing hydropower at the dam. Past efforts to develop hydropower there never came to fruition. 

Design plans include replacing and automating old gate structures and converting what was once a large sluiceway to pass logs into a new functioning gate to help facilitate project construction, future maintenance and improve overall operability. 

“You always want redundancy when talking about water control infrastructure, this helps us have maximum redundancy, maximum readiness,” said John Callagahan, executive director of the regulating district. 

The dam’s rehabilitation would include a comprehensive repointing of masonry joints throughout the structure, replenishing mortar that has deteriorated over the decades. It would also help reduce a consistent flow of water through the dam’s large downstream stone face – one of the most visible signs of repair needs and something that has been noted in inspection reports for over a century.

“It looks more concerning than it actually is,” said Greg Johnson, an engineer at Bergmann Associates. 

During the presentation, Johnson explained that the structure’s large masonry wall originally not intended to pass water would be raised a foot and altered to serve as an auxiliary spillway, passing water when the Indian Lake reservoir was especially high. The dam is required to accommodate 50% of the flood created by what is considered “probable maximum precipitation” at the site, under state rules, but the upgrades would withstand even larger floods, Johnson noted. 

“Just because the state mandates you design for the half [probable maximum flood] doesn’t mean Mother Nature can’t give you the 0.6 PMF,” Johnson said. 

The construction plan aligns with Indian Lake’s typical drawdown schedule, so water levels will not have to be lowered to accommodate repairs. An old wood debris boom and an unsafe walkway over the dam would be replaced. A large retaining wall would need to be constructed next to an existing abutment wall to support improvements to the structure. Numerous anchors will be placed within the structure to improve its overall stability.

DEC requested the district also establish a new canoe and kayak access point and small parking lot near the lake’s northern outlet as part of the project. The new water access would be down Indian Lake Dam Road off of Jerry Savarie Road. 

Project engineers said the design plans were submitted to DEC dam safety officials in January and that the department’s approval was a critical step in sticking to the planned timeline. If a contractor was selected between July and September, initial work could begin in the fall, according to the plan. The bulk of construction would take place next spring and summer, with other work timed to take place during the lower reservoir levels later in the year. 

Editor’s note: This story has been updated to include information about local residents expressing an interest in developing power generation at the dam.