The Gulf of Maine is an international watershed in the North Atlantic stretching north from Provincetown at the tip of Massachusetts Bay in the Commonwealth of Massachusetts to Cape Sable on the Bay of Fundy in the province of Nova Scotia in Canada. For over 13,000 years, the Gulf has been developed around access to the coast for fishing, trading, and recreation. Today, these coastal development patterns put the cultural landscapes, economies, communities, and aging infrastructure systems along the Gulf at risk.
Climate Futures on the Gulf of Maine uses place-based scenario planning to illustrate the risks, vulnerabilities, and plausible futures for ten infrastructure systems along the rim of the Gulf. Place-based scenario planning is a method of long-term strategic planning that creates representations of multiple, plausible futures that are used to inform decision-making in the present. While complementary to probabilistic models used to forecast future vulnerabilities, scenario-based planning shifts emphasis from statistical probability to ways of thinking about the future. The goal of place-based scenario planning is not to predict the most likely outcome, but to reveal biases and blind spots in complex and non-linear situations.
Climate Futures uses the medium of landscape representation to surface the cultural value systems embedded in existing infrastructural systems, and position landscape as a driver when evaluating design from individual infrastructures to the Gulf of Maine watershed.
Infrastructure > Water
SACO WATER TREATMENT PLANT
68 Front Street
Saco, ME 04072
The Saco Water Treatment Plant 1 treats wastewater produced in the City of Saco on the unceded land of the Sokoki, or Saco peoples. 2 The plant lies within two vertical feet of the tidally influenced Saco River, which forms the municipal boundary between the City of Biddeford to the south and the City of Saco to the north. The Saco Water Resource Recovery Facility lies 3 miles (4.8 kilometers) and four dams downstream of the Saco River Drinking Water Resource Center, which provides drinking water for the region. Together, the wastewater treatment, four dams, and water treatment plant illustrate the ways that water infrastructure systems have been constructed, and are now being adapted, in ways that ignore and often damage their sources, in this case, the Saco River.
The Saco River 3 runs 105 miles (168 kilometers) from Crawford Notch in the White Mountains in New Hampshire to its outlet in Biddeford and Saco where it discharges into Saco Bay. 4 5 Biddeford and Saco are both former industrial cities that developed during the 1820s around rapids that flow and drop around Factory Island in the middle of the Saco River. Four dams: Bradbury, Spring Island, West Channel, and East Channel, were constructed to power the industrial mills in the two Cities. 6 7 Today, these dams are collectively known as the Cataract Hydroelectric Project, and are owned and operated by a private company. 8 Since 1994, the dams have undergone a series of improvements to ensure diadromous fish passage by installing ladders and lock systems. 9 These piecemeal improvements do not address the underlying habitat degradation caused by the dams and other development along the river, including wastewater and water treatment systems. 10
The wastewater plant is owned and operated separately from the region’s water treatment facility, the Saco River Drinking Water Resource Center, which is privately owned and operated by the Maine Water Company. 11 While these two systems are deeply connected to the health of the Saco River, they operate at different scales. The Maine Water Company draws drinking water upstream from the river, ponds, and wells and processes it in its facility before distributing drinking water to customers in four municipalities across the broader Saco Bay region, while the Saco Water Treatment Plant treats Saco’s sewage before discharging cleaned water into the Saco River.
The Saco River Drinking Water Resource Center was upgraded and relocated in 2022 in response to flood risks along the Saco River, while the Saco Water Resource Recovery Facility is currently being upgraded.
The Saco Water Treatment Plant has flooded during previous king tides and storms, and is increasingly vulnerable to sea level rise and storm surge that exacerbate the River’s tidal influence, stormwater melt from the adjacent hill, and hydraulic backups during periods when water cannot be released into the River. 12 13 The plant is at risk of inundation at the River’s highest astronomical tides with 1.6’ of sea level rise. 14 The improvements to the wastewater treatment plant are expected to be finished by 2027, and include an increase in capacity, secondary treatment installation, increasing the elevation of treatment systems, and relocation of critical electrical assets to ensure they do not flood in the event of an emergency. 15
In short, the privately owned water plant was moved out of the floodplain. The publicly owned wastewater treatment plant was not moved to higher ground. This would require relocating the collecting pipes, which transport sewage by gravity to the treatment plant. 16 17 These two projects, and the dams between them, illustrate the challenges in climate adaptation at a watershed scale.
Sea level rise, habitat degradation, and erosion along the Saco River are all ongoing processes that will necessitate additional upgrades to water infrastructure systems in the near future. The uncertainty around when this will be required presents an opportunity to proactively consider further armoring the treatment plants in place, or installing riparian buffers, wetland terraces, and undamming the Saco River along its course to improve the water quality and ecological health of the watershed.
Scenario 0: Storm of the Century 2030
Early during the storm, heavy precipitation overwhelms Saco’s sewage system, discharging wastewater through its combined sewer overflow (CSO) outfalls. The Saco River overflows its banks, flooding the Water Treatment Plant with sewage. The cleaning process takes a week, during which time residents live with a boil water advisory.
Scenario 1: Fortified Systems
A berm and revetment are installed to protect the Water Treatment Plant from flooding.
Scenario 2: Catchment Commons
A terraced wetland filtration system is installed at the Water Treatment Plant campus. The system captures wastewater from the nearby combined sewer outflow (CSO) outfall and purifies wastewater before releasing it into the Saco River. The Water Treatment Plant continues to serve 50 million customers in its limited footprint.
International Watershed | Gulf of Maine | Hydrologic Unit Code |
Region (HUC-2) | New England | HUC 01 |
Subregion (HUC-4) | Saco | HUC 0106 |
Basin (HUC-6) | Saco | HUC 010600 |
Subbasin (HUC-8) | Saco River | HUC 01060002 |
Watershed (HUC-10) | Saco River-Frontal Saco Bay | HUC 0106000211 |
Subwatershed (HUC-12) | Outlet Saco River | HUC 010600021105 |
The project currently under construction to upgrade the existing wastewater treatment facility is called the Saco Water Resource Recovery Facility.
Maine Historical Society, “Headwaters of a community: Sowacatuck, Chouacoet, and the sea,” Biddeford History & Heritage Project, accessed June 11, 2025, biddeford.mainememory.net/page/1596/display.html#:~:text=The%20tribes%20associated%20with%20the,in%20Cumberland%20and%20York%20Counties.
Like many other Rivers in the Gulf of Maine, including the Penobscot, Saint John, Androscoggin, and Kennebec Rivers, the falls at Factory Island, east of the Water Treatment Plant, are a result of glacial deposits that blocked the course of the Saco River through its preglacial river valley, forcing the river over rapids on the way to the Gulf. See Joseph T. Kelley, Alice R. Kelley, and Spencer Apollonio, “Landforms of the Gulf of Maine,” in From Cape Cod to the Bay of Fundy: An Environmental Atlas of the Gulf of Maine, ed. Philip W. Conkling (Cambridge, MA: MIT Press, 1995), 36.
Saco Bay is part of the Casco Bay region in southern Maine. The region encompasses 41 municipalities, including Portland, South Portland, Saco, and Biddeford. While the region is only 3% of the State of Maine’s geographic land area, it is home to one quarter of the State’s population. United States Department of Homeland Security, “Casco Bay Region Climate Change Resiliency Assessment” (Washington, D.C.: United States Department of Homeland Security, 2016): 20, www.digitalcommons.usm.maine.edu/cgi/viewcontent.cgi?article=1192&context=cbep-publications.
One dam, located upstream at Steep Falls to serve manufacturing, including the Androscoggin Pulp Mill, was removed after the mill burned down. Portland Press Herald, Aerial Photograph of Steep Falls, Standish, ca. 1936, 1936, 10.2 cm x 12.7 cm, 1936, Maine Historical Society, www.mainememory.net/record/109092.
In the 1990s, Central Maine Power Company proposed to remove the Bradbury and Spring Island dams due to requirements to construct fish ladders, which were estimated to cost $2.5 million ($5.6 million in 2025). Portland Herald Press, “A plan by Central Maine Power (CMP) to remove the Bradbury and Spring Island dam,” Portland Herland Press, January 26, 1993.
There are fourteen dams along the Saco River, most of which, like the Cataract Dams, were constructed to power industrial mills. Today, there is little electricity derived from hydropower, but few dams have been removed. Dams build up nutrient-rich sediment, limiting the flow of nutrients to downstream food chains. Philip W. Conkling, ed., From Cape Cod to the Bay of Fundy: An Environmental Atlas of the Gulf of Maine (Cambridge, MA: MIT Press, 1995):161-162.
These four dams are known as run-of-river operations, meaning that the amount of water flowing into the project matches the amount of water flowing out of the project. Of the four dams, the East Channel dam is the only impoundment that generates power. “LIHI Certificate #169 – Cataract Project, Maine,” Low Impact Hydropower Institute, accessed June 20, 2025, www.lowimpacthydro.org/lihi-certificate-169-cataract-hydroelectric-project-maine.
The Saco River supports American eel, Atlantic salmon, river herring, and American shad. While salmon, herring, and shad are anadromous, meaning they spawn in freshwater and live their lives in the ocean, American eel are catadromous, meaning they spawn in the Atlantic Ocean and travel upstream into freshwater to live the majority of their lives. “LIHI Certificate #169 – Cataract Project, Maine,” Low Impact Hydropower Institute, accessed June 20, 2025, www.lowimpacthydro.org/lihi-certificate-169-cataract-hydroelectric-project-maine.
The City of Saco has five combined sewer overflow (CSO) outfalls. In part due to the sewage released from these outfalls, the mouth of the Saco River is permanently closed to shellfishing. Cindy L. Dionne, “Maine Pollutant Discharge Elimination System (MEPDES) Permit #ME0101117” (Saco, ME: City of Saco, August 15, 2016), 19january2021snapshot.epa.gov/sites/static/files/2016-08/documents/draftme0101117permit.pdf.
The Saco River Drinking Water Resource Center was commissioned in 2022 to provide drinking water to four municipalities: Biddeford, Saco, Old Orchard Beach, and Pine Point. The new building, located in Biddeford, replaced a facility constructed in the Saco River floodplain in 1884. The treatment plant provides 12 million gallons of drinking water to 40,000 people in communities throughout Saco Bay. United States Environmental Protection Agency, “Saco River Water Treatment Facility,” Water Infrastructure Finance and Innovation Act Program (Washington, D.C.: United States Environmental Protection Agency, January 10, 2025), https://www.epa.gov/sites/default/files/2017-07/documents/10_maine_wifiaprojectfactsheet.pdf.
In addition to the treatment plant, Saco’s public water infrastructure, including mains and hydrants are also built in vulnerable coastal areas. An inventory of sewer infrastructure vulnerable to sea level rise also found 3 pump stations; 96 manholes and CSOs; and 19,693 feet of sewer mains that are vulnerable to storm surge during a 100-year storm over 1.6’ of sea level rise. City of Saco, “City of Saco Climate Adaptation & Action Plan” (Saco, ME: City of Saco, August 2024): 69.
City of Saco, “Saco Water Resource Recovery Project,” ArcGIS Story Map, October 7, 2021, storymaps.arcgis.com/stories/804da1c8cb4744469db7f9393f7b5d92.
City of Saco, “City of Saco Climate Adaptation & Action Plan” (Saco, ME: City of Saco, August 2024): 63, https://smpdc.org/vertical/Sites/%7B14E8B741-214C-42E2-BE74-5AA9EE0A3EFD%7D/uploads/Saco_CAAP_COMPLETE_FINAL_8.30.24.pdf.
“Transforming Wastewater Treatment for a Growing City,” Tighe & Bond, accessed June 20, 2025, www.tighebond.com/project/saco-water-resource-recovery-facility-upgrades.
“Project FAQ,” City of Saco Water Resource Recovery Project, accessed June 10, 2025, www.sacomaine.org/departments/water_resource_recovery_division/wrrd_project_faq.php.
Cindy L. Dionne, “Maine Pollutant Discharge Elimination System (MEPDES) Permit #ME0101117” (Saco, ME: City of Saco, August 15, 2016), 19january2021snapshot.epa.gov/sites/static/files/2016-08/documents/draftme0101117permit.pdf.
