Baseline Water Quality Monitoring
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Ambient water quality parameters (Acid Neutralizing Capacity, Conductivity, Dissolved Oxygen, pH Temperature, Turbidity) as well as other nutrient parameters (Chlorophyll-a, Total Phosphorus) and biological parameters (phytoplankton, zooplankton)have been sampled since 2000. Monitoring procedures follow the New Hampshire Volunteer Lakes Assessment Program protocols. Below are average numbers for five most common parameters. For more information on each of these parameters, click here.
Click here to view All Ponds Water Quality Data Graphs 2000-2007
Click here to view All Ponds Water Quality Tables 2000-2007
Crystal Lake Water Quality Graphs 2000-2007
Dorrs Pond Water Quality Graphs 2000-2007
Maxwell Pond Water Quality Graphs 2000-2007
Nutts Pond Water Quality Graphs 2000-2007
Pine Island Pond Water Quality Graphs 2000-2007
Stevens Pond Water Quality Graphs 2000-2007| Total Phosphorus (mg/l) | | 2000 |
2001 | 2002 | 2003 | 2004 | 2005 | 2006 |
Crystal Lake | 0.011 | 0.012 |
0.013 | 0.010 | 0.010 | .014 | 0.017 | | DorrsPond | 0.045 | 0.024 | 0.023 | 0.024 | 0.030 | .026 | 0.030 | | Maxwell Pond | 0.014 | 0.018 | 0.014 | 0.018 | 0.020 | .020 | 0.018 |
| Nutts Pond | 0.017 | 0.023 | 0.024 | 0.030 | 0.020 | .028 | 0.024 | | Pine Island Pond | 0.024 | 0.016 | 0.026 | 0.029 | 0.020 | .020 | 0.026 | | Stevens Pond | 0.019 | 0.025 | 0.018 | 0.017 | 0.020 | .017 | 0.031 |
| Conductivity (uMhos/cm) | | 2000 |
2001 | 2002 | 2003 | 2004 | 2005 | 2006 | | Crystal Lake |
418 | 439 | 442 | 473 | 459 | 511 | 383 | | Dorrs Pond | 408 | 831 | 866 | 759 | 644 | 842 | 455 | | Maxwell Pond | 122 | 155 | 159 | 180 | 151 | 148 | 101 | | Nutts Pond | 582 | 714 | 588 | 786 | 599 | 877 | 469 | | Pine Island Pond | 287 | 383 | 316 | 339 | 256 | 324 | 235 | | Stevens Pond | 769 | 1149 | 1172 | 1258 | 860 | 1099 | 578 |
| Chlorophyll a (mg/m3) | | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | | Crystal Lake | 3.39 | 4.75 | 2.66 | 3.14 | 4.62 | 1.79 | 5.95 | | Dorrs Pond | 30.84 | 14.75 | 9.86 | 18.03 | 15.09 | 8.34 | 12.13 | | Maxwell Pond | 1.55 | 3.17 | 1.68 | 1.65 | 2.30 | 2.33 | 1.89 | | Nutts Pond | 24.84 | 14.01 | 14.34 | 17.13 | 19.31 | 13.49 | 19.53 | | Pine Island Pond | 8.04 | 13.20 | 8.23 | 2.21 | 8.97 | 8.46 | 11.04 | | Stevens Pond | 8.66 | 6.26 | 13.88 | 4.28 | 9.44 | 3.04 | 63.57 |
| Turbidity (NTU) | | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | | Crystal Lake | 0.49 | 0.89 | 3.22 | 0.79 | 1.64 | 0.82 | 1.41 | | Dorrs Pond | 3.76 | 3.70 | 1.86 | 3.42 | 4.61 | 2.45 | 3.13 | | Maxwell Pond | 2.03 | 3.40 | 1.10 | 2.57 | 2.12 | 1.69 | 1.63 | | Nutts Pond | 0.93 | 1.80 | 3.78 | 2.80 | 5.32 | 2.64 | 1.71 | | Pine Island Pond | 1.34 | 1.70 | 3.19 | 3.54 | 3.01 | 2.12 | 2.65 | | Stevens Pond | 2.36 | 2.20 | 2.38 | 2.63 | 2.30 | 1.64 | 2.98 |
| Secchi Disk Transparency (m) | | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | | Crystal Lake | 4.3 | 3.6 | 3.2 | 5.0 | 3.9 | 5.4 | 4.17 | | Dorrs Pond | 1.1 | 1.3 | 1.9 | 1.7 | 1.7 | 2.0 | 1.98 | | Maxwell Pond | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 1.53 | | Nutts Pond | 3.1 | 2.4 | 2.3 | 2.3 | 1.8 | 2.5 | 2.48 | | Pine Island Pond | 1.9 | 1.9 | 1.9 | 1.9 | 1.8 | 1.9 | 1.80 | | Stevens Pond | 2.6 | 2.5 | 2.9 | 2.9 | 2.6 | 3.2 | 2.34 |
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Shoreline Surveys
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Shoreline surveys were conducted at all seven ponds during the spring and summer of 2000. The purpose was to collect information about existing or potential problem areas on pond shorelines. Problem areas targeted included, but were not limited to, eroded banks, trash or other debris, invasive plant species, or inadequate buffers. The areas identified were numerous, and in many cases extreme. Some need immediate attention, while others can be considered a lower priority.
The locations of these areas were mapped using GPS equipment and also manually recorded on maps. Where possible, the surveys were conducted from the shoreline. In cases where the shoreline was inaccessible, the survey was conducted by boat.
This information will be used to plan pond restoration activities in the most beneficial, efficient and logical manner possible. From these shoreline surveys, a list has been compiled of the most pressing pond problem areas. The list is based on the information gathered during the 2000 shoreline surveys and other sources of anecdotal and historical information. It will be updated as required – whether problem areas are remedied and removed, or other problem areas are identified.
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Sediment Sampling
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Sediment depth mapping was conducted during the winter of 2001 with the assistance of the NH Department of Environmental Services at Dorrs, Nutts and Stevens Ponds
Sediment depth mapping was done to determine to what extent certain areas of the ponds have experienced sedimentation. This type of mapping had never been conducted on Manchester ponds so there is no existing historical data to compare with the current sediment depths. The data gathered in 2001 establishes a sediment depth baseline that can be used as a measuring tool in the future.
Among all the ponds mapped, sediment depths ranged from 0 to approximately 24 feet. Dorrs Pond has not seen nearly as much sedimentation as the two natural ponds mapped. This is due simply to the young age of Dorrs Pond. The pond has only been impounded for approximately 230 years. The average sediment depths are as follows:
Dorrs Pond: Average = 2.24 feet; range 0 – 5 feet.
Nutts Pond: Average = 10.83 feet; range 0 – 18.7 feet.
Stevens Pond: Average = 13.22 feet; range 0 – 24.3 feet.
Sediment core samples were collected, using a Glew sediment corer, at all ponds, except for McQuesten, to be analyzed for pesticides, polycyclic aromatic hydrocarbons (PAH’s), polychlorinated biphenyls (PCB’s) and metals contamination. Samples were taken at various sites according to their proximity to inlets or other areas of possible sediment contamination.
Click here to view Analysis Results for Metals Contamination.
Analysis results for PCBs, PAHs and pesticides are contained in the Manchester UPRP Year 2 Report, available at City Hall and the City Library.
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Fish Surveys and Tissue Analysis
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Fish surveys were conducted at Crystal Lake, Nutts Pond, Dorrs Pond and Pine Island Pond by the NH Fish & Game Department using electro-fishing equipment. Population data was recorded and a number of largemouth bass were collected from each pond for tissue analysis. Analyses were conducted by Environmental Research Institute at the University of Connecticut to determine metals, pesticides, and PCB’s concentration in the fish tissue. Largemouth bass were selected as specimens due to their high position in the aquatic food chain. Largemouth bass are also a likely species to be kept (for comsuption) when caught by fishermen.
Fish tissue analysis results were encouraging. All ponds showed relatively low levels of heavy metals with the exception of Pine Island Pond which showed elevated Mercury levels. Fish tissue from Nutts Pond had the highest levels of chromium, copper, manganese and zinc of all the ponds. Pesticides and PCBs analysis results showed little to no bioaccumulation, with just one parameter found above detectable limits at Crystal Lake. No pesticides or PCB’s were found in the fish at any of the other ponds.
Healthy fish populations were found at all ponds sampled. Manchester ponds are characterized as warm-water fisheries. Species found included largemouth bass, chain pickerel, black crappie, common sunfish, pumpkinseed sunfish, bluegill, yellow perch, white perch, brown bullhead, yellow bullhead, american eel, and white sucker. Nutts Pond seemed to exhibit a limiting factor since no largemouth bass greater than 2 pounds were found. Crystal Lake and Pine Island Pond exhibited very robust largemouth bass and sunfish populations. Several largemouth bass weighing more than five pounds were collected at both Crystal Lake and Pine Island Pond. Dorrs Pond also exhibited large populations of several warm-water species of fish.
Click here to view Fish Survey Results
Click here to view Tissue Analysis Data for Metals.
Click here to view Tissue Analysis Data for PCBs & Pesticides.
Fish species posters for each pond are available to download at our Publications Page.
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Water Quality Parameters
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The following is a brief explanation of basic water quality parameters.
Temperature and Dissolved Oxygen
The dissolved oxygen concentration of a water body is directly related to temperature. At colder temperatures, water holds more oxygen than at warmer temperatures. Thus, summer dissolved oxygen concentrations are typically lower than those in cooler months. Dissolved oxygen levels are key to the health of a pond ecosystem. Aquatic organisms cannot survive in extremely low oxygen environments.
A dissolved oxygen (DO) and temperature profile is determined by measuring DO and temperature at each meter of depth from the water’s surface to the pond bottom. Deeper ponds experience pronounced thermal stratification, while in shallower ponds stratification is more subtle, if present at all. Due to biological processes that consume oxygen at the pond bottom, some ponds incur a dissolved oxygen deficit in the hypolimnion (bottom layer).
Pond stratification occurs when different temperatures exist at the top (epilimnion), middle (metalimnion), and bottom (hypolimnion) layers of the water column. Generally, the deeper a body of water, the more pronounced the stratification may become. This is mainly influenced by the amount of solar energy that reaches each water layer. As the sun becomes lower in the sky in the fall, thermal stratification lessens and usually disappears completely by winter.
“Typically, the deeper the reading, the lower the percent saturation of oxygen. Colder waters are able to hold more dissolved oxygen than warmer waters, and generally, the deeper the water, the colder the temperature. As a result, a reading of 9 mg/L of oxygen at the surface will yield a higher percent saturation than a reading of 9 mg/L at 25 meters, because of the difference in water temperature.” (NH Dept. of Env. Services, 1999).
pH
The lower the pH of water, the more acidic the water. The higher the pH of water, the more alkaline the water. Pond pH is crucial to the well being of pond dwelling organisms. A pH of less than 5.5 (acidic) has detrimental effects on fish growth and reproduction. A pH between 6.5 and 7.0 is considered ideal for freshwater ecosystems. The median pH for New Hampshire lakes is 6.7. (NH Dept. of Env. Services, 1999).
Acid Neutralizing Capacity
Acid Neutralizing Capacity (ANC) describes the ability of water to buffer against acidic inputs, like acid rain. This is also known as a lake’s alkalinity. The higher a water body’s ANC, the better it’s ability to buffer acidic inputs. Lakes with low ANC, typical of New Hampshire, are especially vulnerable to the effects of acid precipitation.
A desirable ANC for any lake is greater than 20 mg/L of CaCO. The average ANC for New Hampshire lakes is 6.5 mg/L. (NH Dept. of Env. Services, 1999.)
Conductivity
Conductivity, also known as specific conductance, is a measure of the ability of water to conduct an electric current. This is determined by the number of ionic particles present in the water. High conductivity values may be indicative of non-point source pollution, but at the same time, may be affected even more dramatically by natural geologic features of the watershed.
Conductivity values for New Hampshire lakes that are greater than 100 uMhos are most likely indicative of anthropogenic sources of excess ions in the water, since the average conductivity for New Hampshire lakes is 56.8 uMhos. Anthropogenic sources include urban runoff (metals, sodium), and agricultural runoff (sediment, phosphorus). (NH Dept. of Env. Services, 1999.)
Phosphorus
Phosphorus is the nutrient that generally, or often limits algal production in lakes and ponds. Without excess phosphorus in the system, algal production is hindered and nuisance algal blooms do not occur. As phosphorus amounts increase, so do algae concentrations.
Phosphorus exists as a natural element, but becomes a problem when inputs from such sources as septic systems, erosion, animal wastes, and fertilizer load the water body with excess amounts. The median phosphorus concentration in the epilimnion of New Hampshire lakes is .011 mg/L. (NH Dept. of Env. Services, 1999.)
Chlorophyll a
The concentration of chlorophyll a is an indicator of algal abundance. Because of the presence of chlorophyll a pigment in algae, the relative concentration of chlorophyll a in the water gives an indication of the concentration of algae. As the algae population increases, so does the chlorophyll a concentration.
Chlorophyll a concentrations greater than 10.0 mg/m3 usually indicate an algal bloom. The mean chlorophyll a value for New Hampshire lakes is 7.47 mg/m3. (NH Dept. of Env. Services, 1999.)
Secchi Disk Transparency
Secchi disk sighting measures the depth that one can see into the water. To measure Secchi disk transparency, a black and white patterned disk is lowered into the water, and the depth at which it is no longer visible is recorded. This is indicative of actual water clarity, which is affected by the amount of algae and particulate matter (turbidity) in the water column. Secchi disk readings are somewhat subjective, but generally correlate with chlorophyll a concentrations and turbidity levels.
The mean transparency for New Hampshire lakes is 3.7 meters. (NH Dept. of Env. Services, 1999.)
Turbidity
Turbidity is a measure of suspended matter in the water. The more material (clay, silt, algae) suspended in the water, the higher the turbidity. These materials cause light to be scattered and absorbed, instead of transmitted in straight lines, leading to decreased water clarity. High turbidity readings are often found in water adjacent to construction sites, or waters otherwise polluted. (NH Dept. of Env. Services, 1999.)
The median turbidity for New Hampshire lakes is 1.0 NTU. (NH Dept. of Env. Services, 1999.)
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