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The most important purpose of our association is to monitor and protect the health of our lake. While we are a new association we have already implemented the following three programs.  The first two programs are critical in avoiding infestation of invasive exotic aquatic plants .  The following situation will help you appreciate how important it is to avoid an infestation of exotic milfoil.

Lake Fairlee, West Fairlee, VT  - About 10-20% of this lake, a little smaller than Franklin Pierce, has been impacted by an infestation of Eurasian milfoil for over 15 years. A blog describes the battle this community has been having with it in an article entitled ‘Milfoil at ‘tipping point’ in Lake Fairlee.  

The lake association has been removing it by hand pulling (by divers) for most of those years. Suction harvesting and bottom barriers have been added to the effort in recent years at a cost in excess of $100,000 per year. Costs are shouldered by the state taking on 40%, the towns kicking in about 10% and donations making up the balance. More recently they have resorted to herbicides.


Lake Host Program – Starting in the summer of 2009 with the help of the Hillsborough Conservation Commission we implemented the New Hampshire Lake Association’s Lake Host Program at the Manahan Park boat ramp. The goal of this program is to educate boaters coming to the lake about the problem of invasive aquatic plants and how to prevent their introduction to our lake through the practice of regular boat and trailer inspection upon entering and leaving any body of water.

We will need Lake Hosts for 2016 so if you are interested please contact one of the Board members or email at This email address is being protected from spambots. You need JavaScript enabled to view it..


Weed Watchers - We have about a dozen volunteer Weed Watchers who have been trained by Amy Smagula of the NH DES to regularly survey their area of the lake looking for any suspicious exotic plants. Anyone interested in being notified of the next training session to become a Weed Watcher should contact Todd Birkebak..


Weed Watchers


A small patch of Purple Loosestrife was discovered in 2010 on a south west shore of the lake. Purple Loosestrife is an exotic and invasive plant. It propagates itself by seed dispersion. A single plant can produce over a million seeds a season. The approximately 2 dozen plants were removed and disposed of but we will have to monitor the area closely next season to catch any recurrence of the plant. If anyone sees a suspicious plant anyplace in or around the lake, email This email address is being protected from spambots. You need JavaScript enabled to view it.. For pictures and more information about these plants you can go to the DES website.


For idendifying Aquatic Plants  click here.   For Aquatic plants of FPL click here.




Water Testing

Water, water everywhere and not a drop to drink. Crystal clear high quality sea water may be clean and pure but too salty for drinking. This emphasizes the point that water quality is an elusive concept and that water that is fine for some uses, such as sailing or watering the garden, may not be acceptable for other uses, such as swimming. Since water is an exceptional solvent, many chemicals, particles and even living organisms, may be found either suspended or dissolved in water. There are literally thousands variables that can be found in water. For example oils, pesticides, discarded drugs, and pathogens can be detected in surface waters. Testing for some of these components can be very expensive and such tests are often not cost effective unless there is a good reason to suspect their presence.

The following tests are affordable and provide a cost effective diagnosis for surface waters used primarily for recreational purposes.

Chlorophyll a Chlorophyll is the green pigment plants use for photosynthesis. This pigment is measured in water as an indirect indication for the presence of aquatic weeds and algae. Pierce Lake values for chlorophyll a are good and below the average for NH lakes.  

Conductivity Dissolved ions, such as salt, calcium, iron, potassium and many others, are chemicals that can conduct electricity. These chemicals are generally benign, but could indicate some type of pollution if present at high levels. Pierce Lake values are consistently in the good range.

Acid Neutralizing Capacity (ANC) is one of two tests used to measure the acidity of a lake. ANC measures the ability of water to resist changes in pH by neutralizing the acid input to the lake. New Hampshire lakes have historically had low ANC due to granite bedrock. Low ANC means surface waters are vulnerable to acid precipitation. Pierce Lake is low.

pH This is the measure of the acidity of water. Low values (less than 6) indicate a high acidity and high values (greater than 8) indicate alkaline conditions. Ideal values for surface waters are close to 7. pH values in Pierce Lake are, on average, about 6.24 ((18 tests) but occasionally a value runs below 6. This parameter bears watching but is in the acceptable range.  

Total Phosphorus Phosphorus is a chemical essential for all aquatic life, including both plants and animals. Phosphorus is frequently present at levels that limit growth of aquatic weeds and algae, so this chemical acts as an important control of unwanted algae blooms. Indiscriminant use of lawn fertilizers, which are rich in phosphorus, can lead to eutrophication; a term that describes the process of a lake or pond evolving toward a more swamp - like ecosystem. Total Phosphorus values for Pierce Lake are in the good/average range.

Turbidity/Transparency There are two measures of the transparency (clarity) of water. Suspended solids, such as silt and clay, or algae will reduce the clarity of the water. Dissolved natural compounds, such as lignin from rotting vegetation, can cause the water to be colored and to look like root beer. Turbidity is a chemical measure and in Pierce Lake is generally in the acceptable to good range but this parameter can temporarily get a bit high following a heavy rain and the subsequent runoff from the North Branch River. Clarity is also measured with a Secchi disc which shows how far a person can see into the water. Pierce Lake is in the good range.

Coliform Bacteria (ecoli) These are bacteria that frequent the digestive tract of warm blooded animals. As such their presence is an early warning diagnostic test for more harmful fecal coliforms and other pathogens.Coliform standards are established for drinking and swimming waters. Coliform tests are done by the Manahan Trust near the public beach at Manahan Park and are generally in the acceptable range for public swimming.

The Franklin Pierce Lake Association (FPLA) has begun monitoring water quality parameters 3 times per year at multiple locations in the lake. These tests have determined that the water quality in Pierce Lake falls in the good to average range. Your membership in the Association will help assure that these tests will continue


Tests for Mercury:  In 2009 the NH DES issued the ‘New Hampshire Fish Consumption Guidelines’ in which Franklin Pierce Lake (Jackson Reservoir) was one of 8 bodies of water in NH that were named to be of particular concern regarding high concentrations of mercury and suggested guidelines for limiting the eating of fish from these lakes. We have submitted three different types of fish to be tested for mercury concentration in the last three years.  Anything less than .6 mg/kg is considered safe to consume.  Following are the results:

  • bass - 1.590mg/kg
  • perch - .460 mg/kg
  • trout -  .025mg/kg

Generally bass have a higher concentration and it is recommended to avoid eating them. Trout tend to have lower mercury levels because they are raised in fish hatcheries and later released into water bodies.