Major watershed

New Hampshire is divided into five major river basins as portrayed on the home page of this web site.  They are Androscoggin, Saco, Merrimack, Connecticut, and Piscataqua/coastal.  For the lake selected, this entry lists the major river basin in which the lake lies.
 

Public drinking water supply?

Notes whether the waterbody is an active source for public drinking water.
 

Total phosphorus

Total phosphorus is a measure of all forms of phosphorus in the water, including both inorganic and organic forms.  It is generally the plant nutrient that is limiting in New Hampshire lake waters.  In other words, the amount of phosphorus present in the water column determines the amount of planktonic algae that will grow in the lake.  High phosphorus values generally reflect high algae or chlorophyll a values.

Phosphorus categories (mg/L):
 

< 0.010  0.010 - 0.020              0.020 - 0.040 > 0.040

ideal average more than desirable excessive (nuisance amounts)

Secchi disk transparency

A measure of the water clarity as measured by the naked eye viewing a 20 centimeter black and white disk lowered into the water column until it disappears from view.  It is generally correlated with the amount of planktonic algae in the lake unless the lake is turbid from suspended soil particles (generally a temporary condition from localized erosion).

Secchi categories (ft):
 

< 4 4 - 15       > 15

poor good excellent

Chlorophyll a

An estimate of the total biomass (or amount by weight) of planktonic algae in the lake.

Chlorophyll a categories (ug/L):
 

< 3 3 - 7 7 - 16                         > 16

excellent good more than desirable nuisance amounts

pH

A measure of the hydrogen ion activity in the water or, in general terms, the acidity of the water.  The granitic bedrock of New Hampshire naturally causes New Hampshire lakes to be slightly acidic (just below the neutral value of 7).  Organic acids (natural from decomposing organic matter in wetlands - also resulting in tea-colored waters) and acid deposition (mostly from man-made sources) can further increase the acidity of the water (a decrease in pH).  As the pH decreases to below 6 (more acidic), aquatic organisms including fish may become stressed, and species begin to disappear as the pH decreases further.  Little or no fish life is present when the pH falls much below 5.

pH categories (units):
 

< 5 5 - 5.5 5.5 - 6           > 6

acidified critical endangered satisfactory

For the acid status of NH lakes, click here.
 

Acid neutralizing capacity

The acid neutralizing capacity (ANC), also known as alkalinity, is a measure of the buffering capacity of lake water or its ability to neutralize acid inputs.  Most New Hampshire lakes naturally have low ANC values due to the granitic bedrock (no carbonate to neutralize acids).  Approximately 85% of New Hampshire lakes are at least highly sensitive to acid inputs (ANC < 10 mg/L) and the median ANC for all NH lakes is 5 mg/L.

ANC sensitivity categories:
 

<= 0 >0 - 2 >2 - 5 >5 - 10 >10 - 20            > 20

acidified critical endangered highly sensitive sensitive not sensitive

For the acid status of NH lakes, click here.
 

Macrophyte abundance

A subjective evaluation of the submerged and emergent rooted aquatic plants (macrophytes) growing in the lake.  The type and abundance of macrophytes is more a reflection of sediment type, water depth, and exposure to wind and wave action, than it is of trophic (nutrient) status.  Macrophytes generally obtain their nutrient requirements directly from the sediment and not the water column.  Macrophytes are beneficial to a healthy lake ecosystem but may interfere with man&rsquo;s activities when abundant.

Macrophyte categories:
 

Trophic class

The trophic class of the lake, as determined by NHDES, is a measure of the biological production that occurs in the lake.  It is based on planktonic algae growth, as measured by chlorophyll a and Secchi disk transparency, macrophyte abundance, and the amount of dissolved oxygen in the bottom waters (hypolimnion) of stratified lakes.  The first two parameters are indirectly linked to the phosphorus (nutrient) status of the lake.

Trophic categories:
 

For more information on the NHDES lake trophic classification system, click here.
 

Value

Displays most recent result for parameter if only one sample was taken by monitoring group. If more than one sample was taken in given year by the same monitoring group, then this is an average of the samples. See Single (S) or Average (A) Value to determine if result is a single or average value.

Only results for samples taken on and between June 1^st and September 15^th are used in this table. These results were selected since they would represent water quality during greatest recreational use.

Values are based on samples taken at the deepest spot in the lake. Exceptions to this are Lakes Winnipesaukee, Squam, and Winnisquam. Due to their size, they were split up into sections so the values would be more representative of the specific portion.
 

Single (S) or Average (A) Value

Describes whether the value for the parameter is based on a single (S) result or an average (A) of results.
 

Minimum Value

Minimum (lowest) value used in calculation of Value. If Value is based on a single result, then this is not applicable (N/A).
 

Maximum Value

Maximum (largest) value used in calculation of Value.  If Value is based on a single result, then this becomes not applicable (N/A).
 

# of Measurements

The number of measurements averaged to create the Value.
 

Year

The year of the sample collection for that parameter's value.
 

Info Source

Source of the data for that parameter.
 

DES-LTS DES-VLAP UNH-CFB UNH-FGB UNH-LLMP

NH Department of Environmental Services - Lake Trophic Survey Program NH Department of Environmental Services - Volunteer Lake Assessment Program University of New Hampshire - Center for Freshwater Biology University of New Hampshire - Freshwater Biology Group University of New Hampshire - Lakes Lay Monitoring Program