INDICATORS
The 2023 State of Our Estuaries report presents 21 indicators of estuarine and watershed health that have been selected for their capacity to help us understand the dynamics and conditions of our estuaries. Explore the bubble graphic below to learn about each of these indicators and how they provide an assessment of estuarine health for our region. Each indicator is categorized as either Positive, Cautionary, or Negative to indicate the trend we have observed in the past five years. Click on each indicator to learn more!
Looking for a snapshot for all the indicators? Below the bubble graphic is a table with a summary for each indicator.
Positive
The trend or status of the indicator demonstrates improving conditions,
generally good conditions, or substantial progress relative to the management goal.
Total: 6
Cautionary
The trend or status of the indicator demonstrates possibly deteriorating
conditions, a mixture of positive and negative trends, or moderate progress relative to the management goal.
Total: 13
Negative
The trend or status of the indicator demonstrates deteriorating
conditions, generally poor conditions, or minimal progress relative to the management goal.
Total: 3
Indicator
Status/
Trend
State of the Indicator
Impervious Cover
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Five subwatersheds and ten towns across the Piscataqua Region Watershed have greater than 10% impervious surfaces. There was no decrease in the number of towns with less than 5% impervious surfaces but the Bauneg Beg Pond-Great Works River and Isinglass River subwatersheds increased from 5% to 5.1% and from 4.8% to 5.1% respectively.
Housing
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Since 2015, average housing permit approvals were 515 for multi-units and 549 for single-family units per year. In 2020 multi-unit housing permits fell to 361 while single-family permits increased to 628. Housing stock increased by 20% between 2000 and 2020, with 50,446 new units built.
Stormwater Management Standards and Funding
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As of 2022, 25 of 42 New Hampshire communities have adopted some level of stormwater standards while the 10 Maine communities continue to follow a state standard. Currently no communities have adopted a stormwater utility.
Salt Marsh
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There are currently 5,711 acres of salt marsh in the Piscataqua Region Watershed. While there has been little change in acreage since 2017, marshes are being impacted by sea-level rise and the spread of the invasive common reed (Phragmites australis).
Conserved Lands (General)
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As of April 2022, 18.1% of the total land area in the Piscataqua Region Watershed is under conservation. For the 22 coastal communities in the Piscataqua Region Watershed, 22.3% is conserved, surpassing the PREP goal of 20%.
Conservation Lands (Focus Areas)
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As of 2022, 29.3% of Conservation Focus Areas (CFAs) are conserved in the Piscataqua Region Watershed based on the 2021 New Hampshire Coastal Watershed Conservation Plan. More progress is needed to achieve our goal of 75% of total acres in the CFAs.
Nitrogen Loading (Point Sources)
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Nitrogen loading from point sources for the period from 2017 through 2020 was the lowest (196.9 tons N per year) it has been since consistent monitoring began in 2003.
Nitrogen Loading (Non-Point Sources)
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Nitrogen loading from non-point sources increased from the previous period of 2013 - 2017, by 15% influenced in part by increased precipitation in 2017 and 2018; further reductions are needed to meet management goals. On the other hand, this is the second lowest level since 2003 and the overall trend is improving.
Nutrient Concentrations
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Nitrogen concentrations at most stations are comparable to the lowest measurements on record. Although the Squamscott and Lamprey Stations show increasing concentrations overall, the wastewater treatment facilities in those rivers were recently upgraded, which should have a positive impact going forward.
Dissolved Oxygen
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Trends for dissolved oxygen are neither increasing nor decreasing in the Great Bay and Hampton-Seabrook Estuaries. In the bays, dissolved oxygen generally remains above the threshold of 5 mg/L; however, some tributaries experience many days with dissolved oxygen below 5 mg/L.
Seaweed
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Although nuisance species of seaweeds continue to compete with eelgrass, especially in the Great Bay, overall trends show that seaweeds seem to be decreasing, especially relative to eelgrass.
Eelgrass
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Eelgrass acreage and biomass in the Great Bay Estuary remain low in comparison to historical values; however, the Portsmouth Harbor region has been on a generally positive trend since 2014.
Phytoplankton
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Chlorophyll-a levels are mixed, with increasing trends at some stations and decreasing trends at others. Most data show decreasing concentrations in recent years, even at the stations with increasing long-term trends.
Total Suspended Solids
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Levels of total suspended solids in both the Great Bay and Hampton-Seabrook Estuaries are high relative to other estuaries, and the data at Adams Point indicate a statistically increasing long-term trend despite some signs of recent decreases.
Bacteria
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With the exception of Vibrio spp. increasing due to warmer water temperatures, fecal-indicating bacteria show a statistically significant decreasing trend.
Shellfish Harvest Opportunities
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The percentage of possible acre-days has been on a statistically significant upward trend for the period 2006 to 2021 due to wastewater treatment facility upgrades and expanded testing programs.
Oysters
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Although restoration activities and commercial aquaculture are both increasing, natural oyster reefs remain approximately 80% down from 1993 levels, despite some improvements in recent years.
Softshell Clams
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Clam populations in the Hampton-Seabrook Estuary remain below management goals even during relatively good years, a consistent declining trend since the peak in 1997.
Beach Advisories
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Between 2017 and 2021 there was a significant increase in the number of beach advisories, switching this indicator from "positive" in 2018 to "negative" in 2023.
Migratory Fishes
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In 2021, total migratory river herring returns in both estuaries were at their highest since 1992. However, three of the six tributaries monitored continue to have negligible accounts.
Toxic Contaminants
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While some contaminants are declining, some (e.g., mercury and PCBs) remain high enough to warrant concern. Also, many contaminants of emerging concern (e.g., PFAS) are impacting our communities and have yet to be monitored sufficiently.
Stewardship Behavior
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Total volunteer hours decreased in 2020 likely due to COVID-19 to 6,810 hours, a 76% decrease compared to 2019 average, and the total number of volunteers decreased by 64%. However, in 2021, volunteer hours increased to 15,088, from 582 volunteers across 63 events.