Levels of nitrate in the groundwater in North Windham are high and will likely continue to increase, Windham officials say.

While the higher level doesn’t pose a threat to residents’ health or safety, it does present a “long-term concern for the conservation of natural resources,” says Town Manager Tony Plante.

Several wells for water-monitoring have large concentrations of nitrate that have continued to rise in recent years, one to a level as high as 37 mg/L, according to a draft needs-assessment developed by environmental engineering firm Wright-Pierce,. The action-level set by the Department of Environmental Protection is 10 mg/L.

Plante said because the wells tested are for monitoring purposes and most of North Windham is covered by the public drinking water supply from the Portland Water District, there is no cause for immediate concern, but that the problem does need to be dealt with.

Michael Giggey, senior vice president at Wright-Pierce agrees. The needs assessment indicates there is “difinitely an issue that needs to be addressed” with the town’s groundwater, he said.

The presence of nitrates can primarily be traced back to manure, fertilizer, human waste and food waste leeching into the groundwater. The pollutant is related to increased development in the area and is an indicator of other contaminants in the groundwater said.

Of 26 wells in the North Windham study area that are monitored for water quality since the mid-1990s and mid-2000s, roughly one-third of the wells have seen a decrease in nitrate concentrations, one-third has seen an increase and one-third has seen little change. However, the high levels of nitrate in some of the wells and the projections over 20 and 40 years that show nitrate levels continuing to increase have officials worried.

“The problem is not going away by itself,” Plante said. To encourage and sustain growth away from rurals areas and to the downtown center, the town will need to “develop effective and cost efficient strategies for dealing with wastewater,” he said.

The town first started studying the effects of development on the groundwater roughly 20 years ago, Plante said. In 2012, residents defeated a proposal for a public sewer that would have removed wastewater from the North Windham commercial district and school complex in Windham Center south along Route 302 to the Portland Water District’s wastewater treatment facility in Westbrook.

The $37.8 million project was defeated 6,513-2,036.

Plante said the council will have to discuss and vet several possible approaches for dealing with wastewater from North Windham. Possibilities include adopting a nitrogen ordinance or a public sewer.

While the sewer project was defeated, Plante said the town still needs to develop ways to “address the issue a more cost-effective solution, and and help the community realize its development and resource-protection goals.”

He said the decision about how that will be done is “nowhere close to being made.”

The Wastewater Advisory Committee reviewed a draft version of the needs assessment earlier this month. The council will review a final version of the needs assessment on Dec. 20, and will start the discussion of identifying and evaluating methods for addressing wastewater.

Windham Town Hall