Case Study:
Water and Wastewater Utilities
Planning for Climate Change
CITY OF PORTSMOUTH, NEW HAMPSHIRE
Background
The city of Portsmouth, New Hampshire provides drinking water, wastewater and stormwater services to residents and
local businesses. The utility provides drinking water to nearly 8,300 customers in the communities of Portsmouth,
Greenland, Rye, New Castle and Newington, with a number of large industrial water users spread throughout the area.
About 60 percent of production goes towards commercial or industrial customers, including the decommissioned Pease
Airbase which is now an office park, two power plants, two gypsum factories, a pharmaceutical company, golf courses
and breweries. Average potable water production from both groundwater and surface water sources totals roughly 3.5 to
6.5 million gallons per day (MGD), with a maximum of 8 MGD. The Bellamy Reservoir is the main source of surface
water for the city and has 900 million gallons of storage, with a safe yield of 3.5 to 5 MGD.
The city of Portsmouth treats wastewater for nearly 6,300 customers in the communities of Portsmouth, New Castle,
Greenland and Rye. The city's wastewater treatment consists of two wastewater treatment facilities (WWTF): the Pierce
Island WWTF and the Pease WWTF. The city has recently completed construction of major upgrades to its combined
sewer overflow long-term control plan, and is in a post-construction monitoring phase.
Climate Threats
Flooding from coastal storm surge, sea-level rise and short-term drought are the primary climate-related concerns of the
city. While the Pierce Island WWTF is above the 500-year flood zone elevation, multiple wastewater pumping stations
are currently at risk from coastal flooding. Additionally, the access road to the Pierce Island WWTF floods during king
tides and storm surges which may become more frequent and intense in the future due to sea-level rise, preventing
access to the WWTF during those periods.
Water supply is also of concern to the city due to projected temperature increases and changes to precipitation patterns.
From 2001 to 2002 the city experienced a hot and dry period with little groundwater recharge, which was repeated
during the summer of 2014 when the city of Portsmouth again faced a period of intense heat and reduced precipitation
for approximately six to eight weeks. Demand approached the maximum capacity of the water system - nearly 8 MGD -
however, the city did not need to implement demand reduction measures. A short-term drought is expected to only
affect surface water, which makes up roughly 60 percent of the city's water supply, but a longer-term drought - drought
exceeding one year - would also affect its groundwater. In terms of water recharge, the city found that reservoir levels
tend to increase quickly after a moderate rain event of two inches, but groundwater recharges much more slowly.
The city of Portsmouth has a number of ongoing planning efforts to increase overall sustainability, including a green
infrastructure program and the Coastal Resilience Initiative, designed to reduce the impacts of extreme flooding and to
increase the resilience of infrastructure to coastal flooding and sea level rise. In May 2015, the city received the New
Hampshire Department of Environmental Services' "Source Water Sustainability" award for a variety of water
conservation measures being implemented, including New Hampshire's first customer rebate program that provides
incentives for customers to install more water-efficient appliances.
City of Portsmouth, New Hampshire Case Study — Page 1
SEPA

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Case Study: Water and Wastewater Utilities Planning for Climate Change
Planning Process
To better understand the vulnerability of their utility infrastructure and operations, the city of Portsmouth assessed
potential climate change impacts using the U.S. Environmental Protection Agency's (EPA) Climate Resilience
Evaluation and Awareness Tool (CREAT). The CREAT assessment brought together individuals from EPA and various
departments within the city of Portsmouth to think critically about potential climate impacts, prioritize assets and
consider possible adaptation options.
Adaptation Measures
The city of Portsmouth considered the potential consequences of drought and extreme flooding events on their drinking
water and wastewater utility infrastructure and operations, respectively. To assess each of these potential threats, the
city considered how potential adaptive measures would help lower consequences. See the table below for potential
adaptive measures that were considered.
TYPE
POTENTIAL ADAPTIVE MEASURES
Pumping Station
Flooding
Relocate pump station to a 2- to 5-foot higher elevation to prevent flooding from coastal storm
surge and sea-level rise
Temporary flood barriers such as sandbags to prevent flooding from coastal storm surge and
sea-level rise

Develop and utilize a flood risk management plan
Develop new groundwater sources to help ensure continued reliability of water supplies
Watershed management
Update drought contingency plans that would identify triggers for the utility to encourage or
enforce water conservation actions
Drought
Establish adaptive rates that are use- or customer-based
Conduct supply risk management to help ensure continued reliability of water supplies
Monitor surface water quality to identify additional treatment needs during periods of drought
Contact Information
For more information regarding the city of Portsmouth's climate adaptation planning, contact Al Pratt
at anpratt@citvofportsmouth.com.
City of Portsmouth, New Hampshire Case Study — Page 2
&EPA
Office of Water (4608T)
EPA 800-Q-15-005
December 2015

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