Why Should I Care About Water Trends?

  • As native species composition and distribution change within the Kezar Lake watershed, our surface waters will become more susceptible to aquatic invasive plants, including milfoil.
  • Changing species composition will cause a shift in the ecological balance of water and nutrient cycles that could degrade water quality over time.
  • More frequent and intense rain events will cause more erosion and adsorbed nutrients to wash off the landscape to nearby surface waters, fueling algal blooms.
  • Earlier snowmelt will cause changes in seasonal duration and timing of spring, which greatly impacts life cycles, including the growth and survival rates of loons and other bird species.
  • Earlier spring turnover in the lake and ponds may also fuel algal blooms and cause more prominent late summer low dissolved oxygen levels, impacting fish and other aquatic species.

How Can I Help?

Water Quality Trends

Water quality data has been collected in the Kezar Lake watershed since 1970. These data provide a wealth of long-term information from which we can judge the health of the lake, ponds, and streams in the watershed. Because water quality can fluctuate significantly from year-to-year depending on local conditions and activities within the watershed, analyzing data over a longer time period can reveal subtle, yet steady directional changes in water quality. It is important to identify waterbodies at risk for degrading water quality as a result of climate change or development, so we can take action to combat the effects.

Key for Data Symbols – Current Conditions & Trends


Summary of Current Conditions & Trends

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

Water Body

Sediment Core Sampling Results


Sediments gradually accumulate at the bottom of lakes and reflect biological, geological, and climatological changes within a lake’s watershed over time. We can collect sediment cores from the bottom of the lake to see what the conditions were in Kezar Lake over the past several centuries. Scientists are able to analyze the sediments for their carbon content, mineralogy, and particle-size to infer past lake productivity, stratification, oxygenation, and particulate inflows.

KLWA teamed up with researchers at Plymouth State University to use paleolimnological methods (sediment core analyses) to assess change over time in Kezar Lake and better connect water quality with climate and land use.


Sediment cores were collected from the deepest location in two basins at the northern end of the lake near the Great Brook outlet and the 155-ft deep spot in the upper bay, using a hand-held “surface corer” that collects an entire sequence of sediment without disturbing the sediment-water interface (top-most material in contact with the lake water). The top of the core represents modern material and sequentially deeper sediments in the core represent progressively older material. These collection events were well-attended by KLWA, CCO, and watershed residents, which showcases the genuine community interest in protecting our treasured water resources.

Core samples were freeze-dried and analyzed for organic content by burning the samples in a furnace and weighing the difference before and after, a process called loss-on-ignition (LOI). Planned analyses include 1) core dating using the radioactive element Lead-210, 2) magnetic susceptibility to assess the intensity of land erosion, and 3) sediment geochemistry to determine how the mineral composition of lake sediments has changed over time and to assess heavy metal contamination and potential resuspension, if oxygen level deplete in bottom waters.

Preliminary Results

Preliminary results are presented here, pending further analyses. Since the two sites are similar despite differences in depth and shoreline condition, results indicate that algal growth is the dominant source of carbon in the sediments (Figure 1). However, it appears that the Great Brook outlet periodically receives more carbon from streams or upslope sources (i.e., 10-20 cm). This could be a result of logging and subsequent slash coming down Great Brook. It also appears that the Great Brook outlet experienced increased mineral sedimentation long ago because the carbon content decreases at the bottom of the core. This could be from turbid stream flows entering the lake from Great Brook.


Figure 1. Changes in the amount of organic matter accumulating in the sediments over time at the deep spot of the upper bay of Kezar Lake and at the Great Brook outlet.

Figure 1. Changes in the amount of organic matter accumulating in the sediments over time at the deep spot of the upper bay of Kezar Lake and at the Great Brook outlet.


Results also show recent increases in zinc and lead at the deep spot of Kezar Lake (Figure 2). Further analyses will help us understand the reason for and source of these heavy metal increases.


Figure 2. Geochemistry results for the deep spot of the upper bay of Kezar Lake and at the Great Brook outlet. Cd=cadmium, Co=cobalt, Cr=Chromium, Cu=copper, Ni=nickel, Zr=zirconium, Pb=lead, and Zn=zinc.

Figure 2. Geochemistry results for the deep spot of the upper bay of Kezar Lake and at the Great Brook outlet. Cd=cadmium, Co=cobalt, Cr=Chromium, Cu=copper, Ni=nickel, Zr=zirconium, Pb=lead, and Zn=zinc.

Aquatic Plant Trends

Warming water temperatures, longer growing seasons, and changing precipitation patterns will cause shifts in the extent and abundance of native aquatic plant species.

Many aquatic plant species that thrive under cooler conditions will die out, giving opportunity for southern plant species to take root. This will cause a gradual change in aquatic plant species composition and distribution within the lake and ponds.

Different aquatic plant species have varying levels of nutrient and water needs, a change in which will alter cycling dynamics within the lake and ponds.

An immediate threat to Kezar Lake is the invasion of non-native plants that can outcompete native plants. This threat is being addressed by the Lovell Invasive Plant Prevention Committee.

Fish & Aquatic Bird Trends

Fish are a keystone species for the Kezar Lake fishing community, who have relied on abundant populations of coldwater fish for their recreational enjoyment. These coldwater fish species are extremely sensitive to changes in water temperature and chemistry. Coldwater fish will seek cold, deep areas of lakes, ponds, and streams to avoid warm surface waters in late summer. This can be problematic in productive lakes that have depleted oxygen in bottom waters, leaving little habitat for these fish species to survive.

pH is particularly critical to fish species and other aquatic life as it affects their metabolic functioning and reproductive capacity. This is a concern for Kezar Lake and its ponds given the naturally-low buffering capacity of the soil and water in the watershed. Low-pH rain (5.0) temporarily decreases the pH of surface waters, placing significant stress on aquatic organisms residing in those waters.

If climate change enhances the frequency and duration of precipitation events, then sensitive fish populations may face high disturbance, low pH environments that may be fatal. Because of this, fish can be a good indicator of climate change and should be monitored.

Warmer air temperatures, variable precipitation patterns, and changes in vegetation will very likely reduce the abundance and diversity of aquatic bird species, including the iconic common loon. Earlier snowmelt means changes in seasonal duration and timing, which greatly impacts life cycles, including growth and survival rates of loons and other bird species. Monitoring these populations will help assess the effects of climate change on native species in the watershed.

Aquatic Pathogen Trends

Warmer water temperatures, along with increased population growth, will increase the risk of aquatic pathogens, including bacteria, protozoa, and parasites. While it is difficult to control the spread of these pathogens due to climate change, we can make sure proper waste disposal techniques are used for all existing and future development in the watershed and along the shoreline of Kezar Lake and its ponds.


The Kezar Lake watershed will experience a switch from northern to more southern species as native, cool-weather-loving species are forced further north. This will also foster the spread of more southern species of potentially-harmful pathogens.

Alkalinity in surface waters with a low-carbonate geology will continue to decline due to reduced snowpack and loss of soil CO2. Common loon populations are expected to decrease by 50% in the northeast.

Local Water Trends Summary

Generally, most water quality parameters measured at the lake and ponds are stable and in good to excellent condition, with some notable exceptions.

  • Total phosphorus is elevated at Farrington and Heald Ponds.
  • Chlorophyll-a is elevated at Farrington Pond.
  • Alkalinity shows degrading trends at the upper bay, lower bay, and Cushman, Heald, and Horseshoe Ponds, and is critically, but naturally, low in all waterbodies.
  • pH is generally low (acidic) and at or below the recommended threshold of 6.5 for suitable habitat for aquatic life.
  • Color is elevated at Heald Pond. Water clarity shows improving trends at Kezar Lake and is poor, but stable, at Farrington Pond.
  • Dissolved oxygen is regularly anoxic near the bottom in late summer at Bradley and Horseshoe Ponds.

Climate change threatens aquatic species composition and distribution throughout the Kezar Lake watershed, which makes the landscape more susceptible to southern invaders, including aquatic invasive plants, new tree-shrub species, and aquatic pathogens.

Coldwater fish and northern birds will be forced to migrate or die-out as temperatures warm and seasonal spring timing is altered. These changes will equate to a much different landscape for our children and children’s children to enjoy.

References for Water Trends

Fernandez, I.J., C.V. Schmitt, S.D. Birkel, E. Stancioff, A.J. Pershing, J.T. Kelley, J.A. Runge, G.L. Jacobson, and P.A. Mayewski. “Maine’s Climate Future: 2015 Update.” Orono, ME: University of Maine (2015): 24 pp. www.climatechange.umaine.edu/research/publications/climate-future

Horton, R., G. Yohe, W. Easterling, R. Kates, M. Ruth, E. Sussman, A. Whelchel, D. Wolfe, and F. Lipschultz, 2014: Ch. 16: Northeast. Climate Change Impacts in the United States: The Third National Climate Assessment, J. M. Melillo, Terese (T.C.) Richmond, and G. W. Yohe, Eds., U.S. Global Change Research Program, 16-1-nn. http://nca2014.globalchange.gov/report/regions/northeast

IPCC [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. “Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.” IPCC, Geneva, Switzerland: (2014): 151. http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_FINAL_full.pdf

Meyer, Judy L., et al. “Impacts of climate change on aquatic ecosystem functioning and health.” Journal of the American Water Resources association 35.6 (1999): 1373-1386.

Stewart, Iris T., Daniel R. Cayan, and Michael D. Dettinger. “Changes toward earlier streamflow timing across western North America.” Journal of climate 18.8 (2005): 1136-1155.


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.

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