LAKE GEORGE — A study on septic systems in the town that are within a critical distance of Lake George shows a startling number of residents are not upgrading or pumping their systems properly.

One-third of systems are operating past their life expectancy, which is about 30 years. One-third of systems are operating within their life expectancy, and the remaining third are unknown.

That compounds the discovery that 56 percent of septic systems have an unknown last pump-out date.

Waterkeeper Chris Navitsky, who was hired by the Town Board to conduct the study, said Monday night at the board’s meeting that the facts were “disturbing” and provide grounds for a management program.

The study was funded by a $104,000 state Department of Environmental Conservation grant awarded in 2015. It looked at properties within 500 feet of Lake George, which Navitsky said the Lake George Park Commission considers a critical environmental area. About 550 parcels and about 400 individual on-site wastewater systems were within the project area.

The study is based on septic system surveys sent out to those residents, which drew a 34 percent response rate, as well as town and county records. Navitsky said some septic system plans were actually drawn out on napkins.

The study also used the Lake George Association’s Lake George Watershed Data Atlas, a 2016 publication that delves into things like population and housing, land use, water and sewer infrastructure and residential development potential.

The study did not include an actual test of each septic system, so Navitsky said some assumptions were made, but he hopes it can be a model for other municipalities to use.

Besides pump-out and age of the system, Navitsky and others looked at the age of the home, the size of the tank relative to the number of bedrooms, the flow rate and other factors.

It was also discovered that 21 cesspools are in the study region. Cesspools do not filter waste and can contaminate the soil and groundwater.

“Even one can be bad,” Navitsky said.

Navitsky has also collected algae samples during the summer months and has found that organic pollution — meaning pollution from human waste — is feeding some of the algae species. The algae is also cropping up in some of the hot spot areas where septic systems may be aging or haven’t been pumped out.

The Fund for Lake George and Navitsky are recommending the town put in place programs for inspecting septic systems, pumping out systems and monitoring algae. They’re also recommending the town adopt a septic system transfer law, similar to the one passed by the town of Queensbury. The Lake George Association has also asked municipalities around the lake to consider passing similar laws, requiring septic system inspections whenever a property changes hands.

Councilwoman Marisa Muratori asked Navitsky what would happen if the town didn’t do anything.

The waterkeeper said there will be continuous algae growth, which deteriorates the lake’s water quality.

Deputy Supervisor Vincent Crocitto said, while he thinks everyone wants to do the right thing, he wondered what the incentive would be to get residents to address their systems. Navitsky said replacement tanks could cost a resident between $12,000 and $18,000, but adding treatments like ultraviolet lights could increase that to between $25,000 and $30,000.

The Fund and others are working to obtain grants to help people replace their systems. Dan Barusch, the town’s director of planning and zoning, said there are state funds that could help the town carry out an inspection program, too.

A final report, along with maps that include where the most dramatic problem areas are, is nearly done and will be submitted to the DEC later this month. It is expected to be available to the public on the town’s website in January.