Lawmakers, lake advocates and municipal officials seek compromise on ADUs in shoreland protection zone

A House subcommittee on HB 1540 spent a work session debating whether and how to restrict accessory dwelling units within the 250-foot protected shoreland zone, focusing lawmakers on septic-system protections, impervious-surface impacts and municipal authority.

The discussion opened with Rep. Grant proposing a compromise that would allow ADUs in the protected 250-foot area only when they are within an existing building’s footprint, not as new additions. Rep. Reid sought clarification that ‘‘existing’’ means no expansion of the footprint; Rep. Grant confirmed that interpretation.

Andrea Lamoreaux, president and policy advocate of New Hampshire Lakes, told lawmakers the group ‘‘support[s] tweaking this so that ADUs were allowed within the existing footprint,’’ adding that the main goal is ‘‘environmental protection, reducing additional impervious surface’’ that can increase runoff into lakes.

Municipal officials, represented by Brody Deshais of the New Hampshire Municipal Association, urged caution about a blanket restriction. Deshais said the amendment would ‘‘singl[e] out ADUs within the shoreland protection zone’’ and could create many nonconforming structures, arguing that the Shoreland Protection Act and Department of Environmental Services (DES) standards have traditionally set a floor while municipalities retain discretion to set stricter local rules where appropriate.

Lawmakers focused much of the session on the bill’s septic-language in lines cited to the committee, which reads that a municipality may not impose requirements for a septic system for a single-family home with an ADU that are greater than those required by the Department of Environmental Services. The chair asked whether that language limits only design and installation standards or whether it would also preclude municipal health ordinances covering inspection, maintenance or replacement. Lamoreaux said the restriction should be read as applying to design and installation rather than ongoing maintenance and inspection.

NHMA and New Hampshire Housing recommended alternatives that preserve local discretion while addressing environmental concerns. Deshais suggested allowing municipalities to use conditional-use permits or special exceptions — with clear drafting to prevent ordinances that would effectively prohibit ADUs — and warned that a variance is a higher legal bar than a local special exception. Jack Ruderman, speaking for New Hampshire Housing, said his organization would not support the amendment because it ‘‘singl[es] out ADUs’’ and could limit housing options.

Several committee members said they want to avoid singling out habitable structures from other nonhabitable structures with similar impervious-surface impacts. The chair and legislators discussed three likely near-term actions: striking a redundant detached-ADU statute section (RSA 6 74:73), adding clarifying language to ensure municipal health ordinances (inspection and maintenance) remain permitted, and asking NHMA, New Hampshire Lakes and New Hampshire Housing to draft parity language so towns cannot treat ADUs differently from other structures with the same footprint or impervious impact.

The panel did not take a vote. The chair said the goal is to have draft language ready for a future bill deadline and thanked advocates for collaborating. "I will close the subcommittee work session on HB 1540," the chair said at adjournment.

The next procedural step is for the interested parties and staff to draft the clarified statutory language and present it to the subcommittee; no formal motion or vote occurred during the session.