Cushman Pond – Water Quality

Cushman Pond (Midas #3224) is a non-colored waterbody located in the Town of Lovell, Oxford County, Maine.

Covering 37 acres (0.06 square miles) with a maximum and mean depth of 21 and 15 feet (6 and 5 meters), respectively, the pond drains to Horseshoe Pond, which in turn drains to a tributary to Boulder Brook and eventually Kezar Lake. Cushman Pond is impacted by the growth of the invasive plant, Variable Milfoil, which poses a threat to fish habitat.

Water quality monitoring data have been collected since 1997 at Station 1 (deep spot).

For more information by lake/pond visit www.lakesofmaine.org.

Key for Data Symbols – Current Conditions & Trends

current-condition-and-trends-kezar-lake-watershed

Summary of Current Conditions & Trends

Click a data-point on the chart below for more details

Water Body
Water Clarity
Total Phosphorus
Chlorophyll-a
Anoxic Extent
Temp
pH
Alkalinity
Color

water clarity

( Cushman Pond Historical Annual Water Clarity )

Water clarity at Cushman Pond has remained stable with no statistically significant trend.

Water Clarity or Secchi Disk Transparency: the vertical measure of the transparency of water (ability of light to penetrate water) obtained by lowering a black and white disk into the water until it is no longer visible. Transparency is an indirect measure of algal productivity and is measured in meters (m).

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Total Phosphorus

( Cushman Pond Historical Annual Total Phosphorus )

Since 1997, total phosphorus at Cushman Pond has remained stable with no statistically significant trend. Year-to-year variation in total phosphorus (4 to 10 ppb) is fairly large at Cushman Pond.

Total Phosphorus (TP): The total concentration of phosphorus found in the water, including organic and inorganic forms. TP is one of the major nutrients needed for plant growth. It is generally present in small amounts and limits plant growth in freshwater ecosystems. As phosphorus increases, the amount of algae generally increases. Humans can add phosphorous to a lake through stormwater runoff, lawn or garden fertilizers, and leaky or poorly maintained septic tanks.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Chlorophyll-a

( Cushman Pond Historical Annual Chlorophyll-a )

Since 1997, chlorophyll-a at Cushman Pond has remained stable with no statistically significant trend. Sampling years 1997 and 2012 saw a rise in chlorophyll-a. Nutrient-rich runoff entering the lake during wetter years, combined with warmer air temperatures, can fuel algal growth.

Chlorophyll-a (Chl-a): A measurement of the green pigment found in all plants, including microscopic plants such as algae. It is used as an estimate of algal biomass; higher Chl-a equates to greater amount of algae in the lake.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Anoxic Extent

( Cushman Pond Historical Anoxic Extent )

The anoxic extent at Cushman Pond is minor at <2%. No statistically significant trend was found.

The anoxic extent is calculated as the area of lake at the shallowest depth that experiences dissolved oxygen less than 2 ppm, normalized by the total surface area of the lake. This parameter was used instead of the anoxic factor due to limited data constraints. The anoxic factor is calculated as the anoxic extent multiplied by the duration of anoxia. Too many assumptions are made with estimating duration of anoxia when only 2-3 profiles are collected per year; the anoxic factor is better applied to continuous data series. The maximum anoxic extent was deemed a more appropriate parameter to monitor over time, given the current data collection methodology. See “Dissolved Oxygen” under Definitions for more information on the importance of monitoring dissolved oxygen in surface waters.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Temp

( Cushman Pond Historical Volume-Averaged Surface Temperature )

The volume-averaged surface water temperature for the top 2 meters does not show a statistically significant trend.

Temperature is a measure of the degree of heat in water. Temperature affects the density of water (e.g., cooler water sinks), the solubility of gases (e.g., cooler water holds more dissolved oxygen), the rate of chemical reactions, and the activity of aquatic organisms (e.g., metabolic growth rates peak at different temperatures for different species; some species such as trout and salmon prefer cooler, more oxygen-rich waters; others such as bass prefer warmer waters). Humans can alter temperature by removing shade-providing trees near surface waters, constructing dams or other impoundments that restrict free flowing waters, and causing soil erosion (e.g., turbid water absorbs more heat from the sun). Climate change is predicted to increase surface water temperatures at a much faster rate than the observed increase in air temperature; thus, water temperature serves as a critical indicator of climate change impacts to ecological systems.

Volume-averaged surface water temperature (0-2 m) was calculated using rLakeAnalyzer. Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

pH

( Cushman Pond Historical Annual pH )

Since 1997, pH at Cushman Pond has revealed no statistically significant trend over time. Mean annual pH falls within acceptable ranges for aquatic life. More consistent data are needed to confirm long-term trends.

pH: The standard measure of the acidity or alkalinity of a solution on a scale of 0-14. Most aquatic species require a pH between 6.5 and 8. As the pH of a lake declines, particularly below 6, the reproductive capacity of fish populations can be greatly impacted as the availability of nutrients and metals changes. pH is influenced by bedrock, acid rain or snow deposition, wastewater discharge, and natural carbon dioxide fluctuations.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Alkalinity

( Cushman Pond Historical Annual Total Alkalinity )

Since 1997, total alkalinity at Cushman Pond has degraded by about 2 ppm. The degrading trend in alkalinity is despite the increase in precipitation observed in the last century, suggesting other processes are impacting the natural level of alkalinity in the pond. Cushman Pond has naturally-low alkalinity (or buffering capacity) as a result of its contributing geology (i.e. granite) that lacks carbonates, bicarbonates, and carbonic acid. These low concentrations make Cushman Pond susceptible to changes in pH, particularly from acidic deposition in the form of rain or snow, which can jeopardize the health of freshwater fish species.

Alkalinity: A measure of the buffering capacity of a lake, or the capacity of water to neutralize acids. It is a measure of naturally-available bicarbonate, carbonate, and hydroxide ions in the water, which is largely determined by the geology of soils and rocks surrounding the lake. Alkalinity is important to aquatic life because it buffers against changes in pH that could have dire effects on animals and plants.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

color

( Cushman Pond Historical Annual Color )

Since 1997, color at Cushman Pond has remained stable with no statistically significant trend. Color is highly related to summer precipitation; wetter years show higher color as more materials are washed off the landscape to the lake.

Color: The influence of suspended and dissolved particles in the water as measured by Platinum Cobalt Units (PCU). A variety of sources contribute to the types and amount of suspended material in lake water, including weathered geologic material, vegetation cover, and land use activity. Colored lakes (>25 PCU) can have reduced transparency readings and increased TP values. When lakes are highly colored, the best indicator of algal growth is chlorophyll-a.

Mann-Kendall trend tests were performed on annual water quality data to determine trends over time. Dotted trend lines were added where statistically significant. Sample stations with less than 10 years of data cannot be analyzed for statistically significant trends (too few data points). Data obtained from Maine DEP and FB Environmental Associates.

Definitions

Alkalinity: A measure of the buffering capacity of a lake, or the capacity of water to neutralize acids. It is a measure of naturally-available bicarbonate, carbonate, and hydroxide ions in the water, which is largely determined by the geology of soils and rocks surrounding the lake. Alkalinity is important to aquatic life because it buffers against changes in pH that could have dire effects on animals and plants.

Chlorophyll-a (Chl-a): A measurement of the green pigment found in all plants, including microscopic plants such as algae. It is used as an estimate of algal biomass; higher Chl-a equates to greater amount of algae in the lake.

Color: The influence of suspended and dissolved particles in the water as measured by Platinum Cobalt Units (PCU). A variety of sources contribute to the types and amount of suspended material in lake water, including weathered geologic material, vegetation cover, and land use activity. Colored lakes (>25 PCU) can have reduced transparency readings and increased TP values. When lakes are highly colored, the best indicator of algal growth is chlorophyll-a.

Dissolved Oxygen: The concentration of oxygen that is dissolved in the water. DO is critical to the healthy metabolism of many creatures that reside in the water. DO levels in lake water are influenced by a number of factors, including water temperature, concentration of algae and other plants in the water, and amount of nutrients and organic matter that flow into the waterbody from the watershed. Too little oxygen severely reduces the diversity and abundance of aquatic communities. DO concentrations may change dramatically with lake depth. Oxygen is produced in the top portion of a lake (where sunlight drives photosynthesis), and oxygen consumption is greatest near the bottom of a lake (where organic matter accumulates and decomposes).

E. coli: A type of bacteria that lives in the intestines of warm-blooded animals, including humans. The non-pathogenic form of E.coli is monitored in freshwater systems as an indicator of fecal contamination from wildlife, pets, or humans (e.g., malfunctioning septic systems). The State of Maine sets water quality criteria for bacteria in surface waters to protect designated uses, including primary contact recreation (e.g., swimming) and aquatic life. Levels of E.coli that exceed these criteria indicate the likely presence of harmful pathogens also found in fecal matter. Exposure to or consumption of these pathogens may cause gastrointestinal, respiratory, eye, ear, nose, throat, and skin infections.

Flow: The measure of discharge (area of stream cross-sectional profile multiplied by the average velocity of water moving through that profile). The amount of water flowing through a particular point in a stream is a result of the size of the drainage area (e.g., larger drainage areas feed larger streams), the type of land cover and soils within the drainage area (e.g., forests and loamy soils are able to absorb more water than developed areas and sandy soils), and the local climate (e.g., amount of rain falling within the drainage). Climate change is predicted to increase the frequency and intensity of precipitation, causing greater and more frequent fluxes in discharge; thus, stream flow is a critical indicator of climate change impacts to ecological systems.

pH: The standard measure of the acidity or alkalinity of a solution on a scale of 0-14. Most aquatic species require a pH between 6.5 and 8. As the pH of a lake declines, particularly below 6, the reproductive capacity of fish populations can be greatly impacted as the availability of nutrients and metals changes. pH is influenced by bedrock, acid rain or snow deposition, wastewater discharge, and natural carbon dioxide fluctuations.

Secchi Disk Transparency (SDT): The vertical measure of the transparency of water (ability of light to penetrate water) obtained by lowering a black and white disk into the water until it is no longer visible. Transparency is an indirect measure of algal productivity and is measured in meters (m).

Temperature: The measure of the degree of heat in water. Temperature affects the density of water (e.g., cooler water sinks), the solubility of gases (e.g., cooler water holds more dissolved oxygen), the rate of chemical reactions, and the activity of aquatic organisms (e.g., metabolic growth rates peak at different temperatures for different species; some species such as trout and salmon prefer cooler, more oxygen-rich waters; others such as bass prefer warmer waters). Humans can alter temperature by removing shade-providing trees near surface waters, constructing dams or other impoundments that restrict free flowing waters, and causing soil erosion (e.g., turbid water absorbs more heat from the sun). Climate change is predicted to increase surface water temperatures at a much faster rate than the observed increase in air temperature; thus, water temperature serves as a critical indicator of climate change impacts to ecological systems.

Total Phosphorus (TP): The total concentration of phosphorus found in the water, including organic and inorganic forms. TP is one of the major nutrients needed for plant growth. It is generally present in small amounts and limits plant growth in freshwater ecosystems. As phosphorus increases, the amount of algae generally increases. Humans can add phosphorous to a lake through stormwater runoff, lawn or garden fertilizers, and leaky or poorly maintained septic tanks.

Kezar Lake Watershed Monitoring location Ninja

How Can I Help?

There are many projects that would benefit from your support and involvement. Help us sustain this wonderful environment for many generations to come. Give to KLWA so that we might reserve the watershed for children and grandchildren the same experiences that have been so meaningful to each of us. Volunteer and share your gifts with us.

Donate Volunteer