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Long Pond

Long Pond 
(aka Lower Long Pond)

  • 50 acres (includes both Open Water [45] as well as Deep Marsh [5]at southern tip)
  • Maximum depth exceeds 20 feet
  • Part of the 538 square mile Nashua River Watershed
  • Located within the Petapawag ACEC (Area of Critical Environmental Concern)
  • Likely receives its water from springs and subsurface groundwater flow; does not receive water from upstream surface sources (other streams or ponds) that could carry pollutants or invasive species;
  • At marshy area at southern tip, water exits the pond by flowing over a human-made dam/spillway and then by streams into smaller Upper Long Pond (on private land) and further on, eventually entering into Sandy Pond at its southeastern corner
  • An Eagle Scout project in the early 2000s constructed a wooden pedestrian bridge over the dam/spillway
  • Designated a “Great Pond” by Massachusetts General Law Chapter 91
And if you want to learn more…

 

General Description and History
Long Pond is the surface headwater of the chain of hydrologically-connected ponds and streams that bisect Ayer and eventually convey their waters into the Nashua River:  Long Pond > Sandy Pond > Flannagan Pond (fed into also by Pine Meadow Pond) > Balch Pond > Grove Pond > Plow Shop Pond > Nonacoicus Brook > Nashua River.

Long Pond is also one of Ayer’s two natural kettle ponds (Sandy Pond is the other) formed as a result of glacial drift during the Wisconsin glaciation period 85,000-11,000 years ago – often referred to as the “last ice age.”

This pond is only developed along portions of its eastern shore.  In addition, National Grid power lines cross over the pond from west to east.  According to a 2016 Geosyntec Consultants study, Long Pond “provides a relatively wide range of high-quality aquatic habitats” ranging from floating bog-mats and scrub-shrub vegetation at its northern end to sparsely-vegetated open water that transitions at its southern end into an extensive shrub swamp and bog system.  Carnivorous herbaceous plant species such as spatulate-leaved sundew and pitcher plants can be found in this pond.  Long Pond has possibly the highest diversity of species in Ayer ponds as well as being the only pond, thus far, exhibiting entirely native plant assemblages.  The lack of non-native species means that this pond has not yet required interventions to manage the growth of invasive plants.  The lack of upstream surface water discharge into Long Pond, that could carry pollutants or help spread invasive species, has helped it maintain its unusually pristine state in terms of water quality, wildlife habitat, and plant communities.

Long Pond (with Sandy Pond) is also a Massachusetts “Great Pond.”  Great Ponds are natural bodies of water, larger than 10 acres, that the Commonwealth of Massachusetts designates as public water.  The land under Great Ponds is therefore owned and held in trust by the Commonwealth in order to protect public interest and access to these waterbodies.  In 1866, Massachusetts General Laws (MGL) Chapter 91 codified into State law a policy that was first established by the Colonial Ordinances of 1641-1647.  The Ordinances established that the public had fundamental rights and interest in its natural resources.  It was the duty of the government to preserve and enhance these resources as well as to protect the public’s right to use them for a variety of activities.  Across the centuries, these activities have included:  fishing, hunting, swimming, boating, skating, navigation, and other forms of recreation.  At one time this even included the cutting of ice for transport and sale since Ayer was once home to at least two icehouse companies, the Boston Ice House and the Ayer Ice Company, back in the days before modern refrigeration became both possible and widespread.

Trophic Status
Ponds, lakes and other surface waterbodies can be evaluated on scales that rate their trophic status.  This status indicates the amount of ‘biological productivity’ (or total weight of living biomass at time of measurement) that a waterbody sustains.  Biomass in a waterbody is usually dominated by either aquatic vegetation or algae.  Waterbodies can range from oligotrophic – less biomass/’good’ water quality; mesotrophic – moderate biomass/’fair’ water quality; and eutrophic to hypereutrophic – high/dense biomass/’poor’ water quality.  Too many ‘nutrients’ in a waterbody (especially from phosphorus and nitrogen runoff from stormwater, nearby fertilizer use, septic systems, etc.) will lead to an increase in plant and/or algae growth and a decrease in water quality as the process of eutrophication continues.  While eutrophication is a natural process of nutrient enrichment in aquatic ecosystems that takes place gradually over time, it can be dramatically accelerated by the impact of human activities that increase the flow of nutrients into waterbodies and their surrounding watershed.

According to the Geosyntec Consultants study of Ayer Ponds completed in 2016, as measured by the Carlson Trophic State Index (TSI) model, Long Pond rates as mesotrophic.  The Carlson TSI uses water clarity and measurements of Total Phosphorus (TP) and Chlorophyll-a to make its assessment.  A different model for evaluating eutrophication is the Vollenweider model which uses measurements of a pond’s ‘flushing rate’, the TP load entering the pond from external sources, and the internal TP concentration already there [i.e. from sediment and plant decomposition]).  Like the Carlson TSI, the Vollenweider model also assesses Long Pond as mesotrophic.  Using this and other data, the Geosyntec study described Long Pond as unusually “pristine” and “a regionally significant example” of a healthy pond that sustains wildlife habitat and a “diverse native aquatic plant community.”

Impairment
The Federal Clean Water Act (effective in 1972) governs water pollution in the United States, and requires states to identify waterbodies that do not meet EPA standards and are designated as “impaired.”  Long Pond is not listed as an impaired waterbody in Massachusetts.

This sign project was funded by a community grant from the Nashua, Squannacook, and Nissitissit River Wild & Scenic Stewardship Council.