Every three years, the Piscataqua Region Estuaries Partnership (PREP) publishes a State of the Estuaries report that communicates the status and trends of key environmental indica tors for the Great Bay and Hamp ton-Seabrook estuaries and the Piscataqua Region watersheds.
|The newly-issued 2009 State of the Estuaries Report concludes that the environmental quality of the Piscataqua Region estuaries is declining. Eleven of 12 environmental indica tors show negative or cautionary trends – up from seven indicators classified this way in 2006.|
The most pressing threats to the estuaries relate to population growth and the associated increases in nutrient loads and non-point source pollution.
• Watershed-wide development has created new impervious surfaces at an average rate of nearly 1,500 acres per year. In 2005, there were 50,351 acres of impervious surfaces in the watershed, which is 7.5 percent of the watershed’s land area. Nine of the 40 subwatersheds contained over 10 percent impervious cover, indicating the potential for degraded water quality and altered stormwater flow. Land consumption per person, a measure of sprawling growth patterns, continues to increase.
• The total nitrogen load to the Great Bay Estuary increased by 42 percent in the past five years. In Great Bay, the concentrations of dissolved inorganic nitrogen, a major component of total nitrogen, have increased by 44 percent in the past 28 years. The negative effects of the increasing nutrient loads on the estuary system are evident in the decline of water clarity, eelgrass habitat loss, and failure to meet water quality standards for dissolved oxygen concentrations in tidal rivers.
The negative or cautionary trends for other indicators also are troubling.
• Oyster and clam populations have increased from historic lows a few years ago but remain depressed compared to historic abundance.
• Toxic contaminants affect nearly one-quarter of estuarine sediments, and concentrations of compounds associated with petroleum products are increasing in the tissues of shellfish from the Piscataqua River. However, concentrations of other toxic contaminants in shellfish tissue are declining.
• Migratory fish returns to the estuary are limited by factors including water quality, passage around dams, and flooding.
• Bacteria concentrations declined significantly in the 1990s but have more recently leveled off, and water quality standards for swimming and shellfishing are not being met in all areas.
To counteract these trends, PREP and others have worked to conserve land, restore habitats, and eliminate pollution sources in the coastal watershed. Considerable progress has been made toward PREP’s land conservation goal of protecting 15 percent of the watershed area by 2010 and salt marsh restoration goal of 300 acres. By the end of 2008, 76,269 acres (11.3 percent of the watershed) were permanently protected from development and 280 acres of salt marsh were restored in New Hampshire. However, despite significant efforts, restoration goals for submerged habitats (oyster reefs and eelgrass) are far below target levels.
The Piscataqua Region estuaries retain many positive attributes and continue to serve important ecological functions. Restoration of habitats and high water quality still can be achieved. However, the increasing pressures of development in the watershed will need to be matched with increasing effort and awareness in order to reduce pollutant loads and protect habitats.
Other Indicator Reports