An Act to Address Housing Density Requirements in Sole Source
Maine Legislature, Session 132, LD 1914
Committee: State and Local Government
Sponsors: STOVER
Amends: 30-A MRSA §4364, 30-A MRSA §4364-A, 30-A MRSA §4364-B, 30-A MRSA §4364-C, 30-A MRSA §4364-D

Legislative Document
No. 1914
H.P. 1275
House of Representatives, May 6, 2025
An Act to Address Housing Density Requirements in Sole Source 
Aquifer Island and Peninsular Communities
Reference to the Committee on State and Local Government suggested and ordered printed.
ROBERT B. HUNT
Clerk
Presented by Representative STOVER of Boothbay.
Cosponsored by Representatives: EATON of Deer Isle, GEIGER of Rockland, HEPLER of 
Woolwich, MATLACK of St. George, MITCHELL of Cumberland, STROUT of Harrington, 
Senators: GROHOSKI of Hancock, RENY of Lincoln.
Be it enacted by the People of the State of Maine as follows:
Sec. 1.  30-A MRSA §4364, sub-§10 is enacted to read:
10.  Application.  For a sole source aquifer municipality, the applicability of this 
section is governed by section 4364-D. For the purposes of this subsection, "sole source 
aquifer municipality" has the same meaning as in section 4364-D, subsection 1, paragraph 
C.
Sec. 2.  30-A MRSA §4364-A, sub-§11 is enacted to read:
11.  Application.  For a sole source aquifer municipality, the applicability of this 
section is governed by section 4364-D. For the purposes of this subsection, "sole source 
aquifer municipality" has the same meaning as in section 4364-D, subsection 1, paragraph 
C.
Sec. 3.  30-A MRSA §4364-B, sub-§14 is enacted to read:
14.  Application.  For a sole source aquifer municipality, the applicability of this 
section is governed by section 4364-D. For the purposes of this subsection, "sole source 
aquifer municipality" has the same meaning as in section 4364-D, subsection 1, paragraph 
C.
Sec. 4.  30-A MRSA §4364-C, sub-§4 is enacted to read:
4.  Application.  For a sole source aquifer municipality, the applicability of this section 
is governed by section 4364-D. For the purposes of this subsection, "sole source aquifer 
municipality" has the same meaning as in section 4364-D, subsection 1, paragraph C.
Sec. 5.  30-A MRSA §4364-D is enacted to read:
§4364-D.  Housing density exemption for certain island and peninsular municipalities
1.  Definitions.  For the purposes of this section, unless the context otherwise indicates, 
the following terms have the following meanings.
A.  "Hydrogeology" means the science of the occurrence, distribution and movement 
of groundwater.  
B.  "Sole source aquifer" means an aquifer designated by the United States 
Environmental Protection Agency pursuant to 42 United States Code, Section 
300h-3(e) as the sole or principal drinking water source for an area that if contaminated 
would create a significant hazard to public health.
C.  "Sole source aquifer municipality" means a municipality that is located wholly or 
partially on an island or peninsula and relies on a primary drinking water supply 
derived from a sole source aquifer.
2.  Exemption from increased housing density requirements pending geological 
evaluation.  Notwithstanding any provision to the contrary in sections 4364 to 4364-C, a 
sole source aquifer municipality is not required to allow increased housing density in an 
area within the municipality unless a licensed geologist determines that the groundwater 
and septic capacity of the municipality can support an increase in housing density. A sole 
source aquifer municipality shall pursue the geological evaluation described in subsection 
consistent with the time frames established in rules adopted by the Department of 
Economic and Community Development pursuant to subsection 7.
3.  Evaluation of groundwater and septic capacity.  A sole source aquifer 
municipality shall contract with a qualified geologist who is licensed in this State and has 
expertise and experience in the field of hydrogeology to determine whether the 
groundwater and septic capacity within the municipality or a particular area within the 
municipality can support an increase in housing density. The evaluation process must 
include an analysis of the following: 
A.  The specific soils and geology of the area being considered for an increase in 
housing density;
B.  The capacity of existing groundwater resources to support additional density 
without adversely impacting drinking water supplies;
C.  The ability of septic systems to function safely and effectively, accounting for 
existing and planned future development; and
D.  The proximity to salt water and potential impacts on groundwater and septic system 
performance.
After completing the analysis as required pursuant to this subsection, the geologist 
performing the evaluation shall complete a report that includes the geologist's 
recommendations and findings, including whether the evidence shows that the groundwater 
and septic capacity in the area evaluated can support an increase in housing density. 
4.  Municipal action following evaluation report.  This subsection governs the effect 
of the evaluation report under subsection 3 on the obligations of the sole source aquifer 
municipality with respect to the requirements of sections 4364 to 4364-C. 
A.  If the evaluation report demonstrates that the municipality or a particular area within 
the municipality can support increased housing density, the sole source aquifer 
municipality shall develop or amend its comprehensive plan and zoning ordinances to 
allow increased density as required under sections 4364 to 4364-C, but only to the 
extent the area can support the increase consistent with the findings of the evaluation 
report. 
B.  If the evaluation report demonstrates that the municipality or a particular area within 
the municipality cannot support increased housing density, the municipality remains 
exempt from the requirements of sections 4364 to 4364-C for the area determined to 
be unable to support increased density.
5.  Implementation date.  Notwithstanding sections 4364 to 4364-C, for a sole source 
aquifer municipality required to comply with sections 4364 to 4364-C as provided in 
subsection 4, paragraph A, wherever the term "implementation date" appears in sections 
4364 to 4364-C, the applicable date is the date the evaluation report completed pursuant to 
subsection 3 is received by the municipality. 
6.  Reporting requirements.  A sole source aquifer municipality shall submit an 
annual report to the Department of Economic and Community Development detailing the 
municipality's progress toward completing the evaluation required under this section and 
any actions taken by the municipality to address housing density. 
7.  Rule-making authority.  The Department of Environmental Protection and the 
Department of Economic and Community Development shall adopt rules pursuant to this 
subsection as follows.
A.  The Department of Economic and Community Development shall adopt rules to 
implement this section, including but not limited to: 
(1)  Rules establishing a time frame in which sole source aquifer municipalities 
must obtain an evaluation pursuant to subsection 3; and
(2)  Other rules establishing guidance for municipal compliance with this section.
B.  The Department of Environmental Protection shall adopt rules limited to: 
(1)  Rules establishing criteria by which sole source aquifer municipalities may 
select a licensed geologist to perform the evaluation required under subsection 3; 
and
(2)  Other rules as necessary to facilitate the performance of the evaluation pursuant 
to subsection 3.   
Rules adopted pursuant to this subsection are routine technical rules as defined in Title 5, 
chapter 375, subchapter 2-A.
SUMMARY
This bill establishes an exemption from the Maine Revised Statutes, Title 30-A, 
sections 4364 to 4364-C for municipalities that are located wholly or partially on an island 
or peninsula and rely on a primary drinking water supply derived from a sole source aquifer. 
The bill provides that such a municipality is exempt from these provisions until a licensed 
geologist has analyzed the groundwater and septic capacity within the municipality or a 
particular area within the municipality and determined that it can support an increase in 
housing density. If the licensed geologist determines in the geologist's evaluation report 
that the area can support an increase in housing, the municipality is required to comply with 
the provisions of Title 30-A, sections 4364 to 4364-C, to the extent that the licensed 
geologist determines the area can support the increase. If the geologist's evaluation report 
indicates the area cannot support an increase in housing density, the municipality is exempt 
from Title 30-A, sections 4364 to 4364-C. 
The Department of Economic and Community Development and the Department of 
Environmental Protection are directed to adopt rules to implement this legislation. The 
Department of Environmental Protection has rule-making authority limited to establishing 
criteria by which municipalities may select a licensed geologist and other rules necessary 
to perform the geological evaluation required under this legislation.