Consultants tell Boxborough planning board current water quantity appears adequate but urge more testing and septic outreach

Emily DeFranco, a team leader at engineering firm Weston & Sampson, presented a comprehensive water‑resources report to the Boxborough Planning Board on March 16, reviewing population projections, groundwater basins, current and projected water demand, and septic‑system records.

DeFranco said the study combined U.S. Census and regional projections with a CommunityViz build‑out analysis that shows additional development potential in town. The firm’s population scenarios through 2050 project roughly a 28% increase in population, and the spatial build‑out identified about 263 potential new dwelling units across Boxborough. “The build‑out shows sort of that increase of 14% or about 263 available or potential new dwelling units,” she said.

On water use, Weston & Sampson estimated current residential demand at about 130.4 million gallons per year and commercial demand at roughly 59.3 million gallons per year, yielding a total near 190 million gallons per year, according to DeFranco’s presentation. The consultants noted a wide future demand range under different commercial‑use scenarios and emphasized the difficulty of isolating recharge rates to the Boxborough portion of the six regional groundwater basins that supply the town.

“Because of the way groundwater basins work, we can’t calculate that for just the Boxborough portion,” DeFranco said, adding that basinwide recharge estimates are in the thousands of millions of gallons per year and that the firm’s hydrogeologist judged the projected demand compatible with likely recharge under the study assumptions.

The presentation highlighted septic‑system vulnerabilities. The report’s GIS inventory identified roughly 1,700 parcels overall and estimated about 1,357 properties on septic systems. DeFranco said about 164 parcels were classified as Tier‑1 (closest to water bodies, in flood zones, or with constraining soils). Of the Tier‑1 records they reviewed, many systems with available inspection dates were older than 20 years.

Recommendations from the study focused on nonregulatory steps and further study: targeted homeowner education about septic maintenance and pump‑outs, development of an expanded septic‑system inventory beyond Tier‑1, a voluntary townwide private‑well sampling program to establish a water‑quality baseline, and further regional coordination on supply and recharge. “Education is the first step when you’re dealing with septic systems,” DeFranco said.

Les Fox, who spoke for the water‑resources committee during the meeting, said the Board of Health recently adopted private‑well testing requirements tied to property transfers and that the new rule will begin creating some water‑quality data, albeit slowly. “If PFAS is found, then you must report that to DEP,” Fox said, adding that testing can prompt costly remediation and make some homeowners reluctant to test.

Board members praised the report’s quantity analysis but repeatedly returned to water quality as an outstanding concern. Planning Board member Mark White said the study “helps us understand quantity,” while several members urged a phased approach focused first on an education campaign and targeted well sampling to establish baselines.

Next steps: DeFranco said Weston & Sampson can help design the sampling program and extend the septic inventory. The firm will provide its slide deck to the planning board for public record and follow up as requested.

Why it matters: Boxborough relies heavily on private wells and small community water systems, and much of the town uses septic systems. As the town considers future development and bylaw changes, the study offers a data‑driven foundation for prioritizing sampling, septic outreach, and regional coordination.