Summer-stratified monomictic lakes are so deep (or large) that they have only one period of mixing or turnover each year (monomictic), and one period of stratification. These lakes are typically thermally stratified only in the summer (warmest water at the surface). Lake Champlain, Cayuga Lake, and Seneca Lake are the three largest summer-stratified monomictic lakes in New York. Seneca Lake is the largest of the Finger Lakes, and the deepest lake entirely within the state with an average depth of 291 feet (89 m) and maximum depth of 618 feet (188 m). Because of Seneca Lake's great depth its temperature remains a near-constant 39 °F (4 °C). In summer the top 10 to 15 feet (3.0 to 4.6 m) warms to 70–80 °F (21–27 °C).
Very few lakes in NY have the physical setting to meet the minimum size and depth thresholds that define the community (e.g., Lake Champlain, Cayuga Lake, and Seneca Lake). The condition of these lakes are threatened by nutrient and pollution runoff; and numerous aquatic invasive species.
The number and acres of summer-stratified monomictic lakes in New York have likley remained stable in recent decades given that very few lakes in NY have the physical setting to meet the minimum size and depth thresholds that define the community (e.g., Lake Champlain, Cayuga Lake, and Seneca Lake). However, the water quality of these lakes is threatened by excessive run-off of nutrients, pathogens, and toxins from the surrounding watershed; and they are also threatened by the spread of numerous aquatic invasive species.
The number and acres of summer-stratified monomictic lakes in New York are probably comparable to historical numbers, but the water quality of several of these lakes has likely declined significantly as a result of several human caused disturbances (e.g., nutrient and pollution run-off, invasive species, watershed development, etc.).
Where practical, establish and maintain a lakeshore buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the lake. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and current land use. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the lake and surrounding landscape. For example, roads should not be routed through the lakeshore buffer area. If a lake must be crossed, then bridges and boardwalks are preferred over filling and culverts. Restore lakes that have been affected by unnatural disturbance (e.g., remove obsolete impoundments and ditches in order to restore the natural hydrology). Prevent the spread of invasive exotic species into the lake through appropriate direct management, and by minimizing potential dispersal corridors. Look for more lake-specific information on this topic in the following management plans: Opportunities for Action for Lake Champlain (LCBP 2017), Seneca Lake Watershed Management Plan (Genesee/Finger Lake Regional Planning Council 2012), and Cayuga Lake Watershed Restoration and Protection Plan (Cayuga Lake Watershed Network. 2017).
Threats to water quality in Lake Champlain include the following: Nutrient Pollution: Excess phosphorus combined with warm temperatures and calm conditions can sometimes result in toxic cyanobacteria blooms. Most of the phosphorus comes from runoff from developed areas, lawns, and farms. Pathogens: Disease-causing bacteria, viruses, and parasites are present in human and animal waste. During rain events, runoff carries Escherichia coli (E. coli), giardia, cryptosporidiosis, and flatworms into streams and rivers and eventually the lakes. Agricultural fields, faulty septic systems, and pet waste are common sources of pathogens. Toxic Substances: polychlorinated biphenyls (PCB), mercury, dioxins/furans, chlorinated phenols, persistent organics, solvents; pesticides (herbicides, insecticides, fungicides); pharmaceuticals and personal care products (medications, antibiotics, antidepressants, fragrances, surfactants, detergent metabolites, antimicrobial additives), trace elements (arsenic, manganese, cadmium, chromium, lead, nickel, silver, zinc, copper); road de-icing salts; cyanobacterial toxins (aycrocystin, anatoxin).
Seneca Lake is threatened by pollution and runoff from the following sources: agricultural activities, forestry, urban landscapes, chemical and petroleum storage, spills, landfills and solid waste disposal, mining activities, road salt, road-bank erosion, boating activities, onsite and municipal liquid waste disposal, storm water runoff, construction activities, energy development, and air quality.
Threats to water quality in Cayuga Lake include agricultural activity, wastewater sources, and other contributors of nutrients in the watershed. Elevated nutrient and chlorophyll levels in the lake tend to be correlated with the formation of disinfection by-products (DBPs) in finished potable water that would require advanced treatment to meet drinking water standards. DBPs are formed when disinfectants such as chlorine used in water treatment plants react with natural organic matter (i.e., decaying vegetation) present in the source water. Sediment eroded from the landscape enters the extensive surface drainage network in the Cayuga Lake watershed and ultimately is transported to Cayuga Lake.
Summer-stratified monomictic lakes are threatened by the spread of numerous aquatic invasive species, such as alewife (Alosa pseudoharengus), mud bithynia (Bithynia tentaculata), spiny water flea (Bythotrephes longimanus), fishhook waterflea (Cercopagis pengoi), Asian clam (Corbicula fluminea), common carp (Cyprinus carpio), quagga mussel (Dreissena bugensis), zebra mussel (Dreissena polymorpha), scud (Echinogammarus ischnus), bloody red shrimp (Hemimysis anomala), European frogbit (Hydrocharis morsus-ranae), Eurasian watermilfoil (Myriophyllum spicatum), variable leaf watermilfoil (Myriophylluum heterophyllum), brittle naiad (Najas minor), round goby (Neogobius melanostomus), greater European peaclam (Pisidium amnicum), Curly leafed pondweed (Potamogeton crispus), European ear snail (Radix auricularia), rudd (Scardinius erythrophthalmus), tench (Tinca tinca), water chestnut (Trapa natans), and European valve snail (Valvata piscinalis)
Where practical, establish and maintain a lake shore buffer to reduce storm-water, pollution, and nutrient run-off, while simultaneously capturing sediments before they reach the lake. Buffer width should take into account the erodibility of the surrounding soils, slope steepness, and current land use. If possible, minimize the number and size of impervious surfaces in the surrounding landscape. Avoid habitat alteration within the lake and surrounding landscape. For example, roads should not be routed through the lake shore buffer area. If portions of a lake must be crossed, then bridges and boardwalks are preferred over filling and culverts. Restore lakes that have been affected by unnatural disturbance (e.g., remove obsolete impoundments and ditches in order to restore the natural hydrology). Prevent the spread of invasive exotic species into the lake through appropriate direct management, and by minimizing potential dispersal corridors.
When considering road construction and other development activities, minimize actions that will change what water carries and how water travels to this lake community, both on the surface and underground. Water traveling over-the-ground as run-off usually carries an abundance of silt, clay, and other particulates during (and often after) a construction project. While still suspended in the water, these particulates make it difficult for aquatic animals to find food; after settling to the bottom of the lake, these particulates bury small plants and animals and alter the natural functions of the community in many other ways. Thus, road construction and development activities near this lake type should strive to minimize particulate-laden run-off into this community. Water traveling on the ground or seeping through the ground also carries dissolved minerals and chemicals. Road salt, for example, is becoming an increasing problem both to natural communities and as a contaminant in household wells. Fertilizers, detergents, and other chemicals that increase the nutrient levels in lakes cause algae blooms and eventually an oxygen-depleted environment where few animals can live. Herbicides and pesticides often travel far from where they are applied and have lasting effects on the quality of the natural community. So, road construction and other development activities should strive to consider: 1. how water moves through the ground, 2. the types of dissolved substances these development activities may release, and 3. how to minimize the potential for these dissolved substances to reach this natural community. Look for more lake-specific information on this topic in the following management plans: Opportunities for Action for Lake Champlain (LCBP 2017), Seneca Lake Watershed Management Plan (Genesee/Finger Lake Regional Planning Council 2012), and Cayuga Lake Watershed Restoration and Protection Plan (Cayuga Lake Watershed Network. 2017).
Review and incorporate data from partner organizations to create new occurrence records of summer-stratified monomictic lake for Seneca Lake and Cayuga Lake, and to update the Lake Champlain occurrrence (e.g., Lake Champlain Basin Program, Cayuga Lake Watershed Network, and Genesee/Finger Lake Regional Planning Council).
There is a need to research the composition of summer-stratified monomictic lakes statewide in order to characterize variations. Up to two ecoregional variants are possible (St. Lawrence-Lake Champlain, and Finger Lakes types) with one to few examples of each, potentially differing in dominant, and characteristic vascular plants, fishes, mollusks, and insects.
Research needs for Lake Champlain: 1) Identify critical source regions for nutrient inputs, and most cost-effective ways to reduce inputs - so that management actions can be targeted more effectively and with greater cost efficiency; 2) Improve understanding of biodiversity, including food web dynamics, the impact of non-native species, and potential impacts of climate change; 3) Improve understanding of toxins, including “new-generation” contaminants and their potential impacts; and 4) Improve understanding of water circulation patterns within and among sub-basins – especially in areas with high nutrient levels. This includes continuation, and possible expansion, of meteorological stations needed to monitor wind and weather conditions (Lake Champlain Research Consortium 2008).
Research needs for Seneca Lake include monitoring water quality indicators including the following: number and types of macroinvertebrates; invasive species; algae species that cause harmful algal blooms; excessive erosion and polluted run-off; heavy metals such as mercury; air quality over the watershed; silicates; salt concentrations; water temperatures at various depths; seasonal changes at various depths; viruses that infect aquatic animals such as game fish, and many others (Seneca Lake Pure Waters Association 2017).
Research needs for Cayuga Lake include the following: continue critical water quality monitoring in tributaries of the northern Cayuga Lake watershed; determine the precise sources of nutrient-loading to the lake, that can lead to harmful algal blooms, by using specific bacteria as tracers (SUNY College of Environmental Science and Forestry).
This community is uncommon in upstate New York, north of the North Atlantic Coast Ecoregion. Probably restricted the larger Finger Lakes in the the Great Lakes Ecoregion and the Lake Champlain Valley.
This broadly-defined community may be worldwide. Examples with the greatest biotic affinities to New York occurrences are suspected to span north to southern Canada, west to Minnesota, southwest to Indiana and West Virginia, and southeast to Pennsylvania.
Summer-stratified monomictic lakes are so deep (or large) that they have only one period of mixing or turnover each year (monomictic), and one period of stratification. These lakes generally do not freeze over in winter (except in unusually cold years), or form only a thin or sporadic ice cover during the coldest parts of midwinter, so the water circulates and is isothermal during the winter (similar temperature though the water column). These lakes are typically thermally stratified only in the summer (warmest water at the surface); they are oligotrophic to mesotrophic and alkaline.
The dominant fishes include salmonids such as cisco (Coregonus artedii), and lake trout (Salvelinus namaycush) as well as yellow perch (Perca flavescens), rainbow smelt (Osmerus mordax), rock bass (Ambloplites rupestris), walleye (Stizostedion vitreum), brown bullhead (Ameiurus nebulosus), white sucker (Catostomus commersoni), and northern pike (Esox lucius). Characteristic invertebrates may include the mollusks eastern elliptio (Elliptio complanata), eastern lampmussel (Lampsilis radiata), pocketbook (L. ovata), pink heelsplitter (Potamilus alatus), floaters (Pyganodon cataracta, P. grandis), and mud amnicola (Amnicola limosa). Characteristic aquatic macrophytes include pondweeds (Potamogeton gramineus, P. richardsonii, P. pectinatus), horned pondweed (Zannichellia palustris), naiad (Najas flexilis), waterweed (Elodea canadensis), tapegrass or wild celery (Vallisneria americana), and coontail (Ceratophyllum demersum). A characteristic crustacean of the hypolimnion of Finger Lake examples is Senecella calanoides, which was named after Seneca Lake. Dominant invertebrates of the profundal zone of Lake Champlain are Spheriidae and the oligochaetes Stylodrilus heringianus and Peloscolex variegatus. Winter epilimnion plankton species assemblages are usually well developed. Characteristic plankton may include the following phytoplankton: Fragilaria spp. and Anabaena spp. in summer; Melosira spp. and Cryptomonas ovata in winter; and the following the zooplankton: Daphnia spp., and Diaptomus spp. in summer; Limnocalanus macrurus, and Cyclops bicuspidatus in winter.
Known examples of this community have been found at elevations between -305 feet and 95 feet.
Summer-stratified monomictic lakes can be easily observed from the shoreline where there is public access, or by boat during calm weather.
Berg, C.O. 1963. Middle Atlantic states. Chapter 6 from Limnology in North America. The University of Wisc. Press.
Bloomfield, J.A., ed. 1978a. Lakes of New York State. Vol. I. Ecology of the Finger Lakes. Academic Press, New York.
Cayuga Lake Watershed Network. 2017. Cayuga Lake Watershed Restoration and Protection Plan. Prepared for the Cayuga Lake Watershed Intermunicipal Organization by the Cayuga Lake Watershed Network, Aurora, NY.
Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero (editors). 2014. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke’s Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY. https://www.nynhp.org/ecological-communities/
Fiske, S. and R. Levey. 1995. Survey of native mussel-beds in Lake Champlain. Lake Champlain Basin Program, July 1995.
Genesee/Finger Lake Regional Planning Council. 2012. Seneca Lake Watershed Management Plan: Characterization and Subwatershed Evaluation. Genesee/Finger Lake Regional Planning Council, Rochester, NY.
Greeley, J.R. 1930. II. Fishes of the Lake Champlain watershed. pp. 44-87. in: A biological survey of the Lake Champlain watershed. E. Moore, editor. Supplemental to 19th annual report, New York State Conservation Department, 321 pp.
Hunt, David M. 1998. Community ranking and general description. Lake Champlain, summer-stratified monomictic lake. Unpublished report. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY.
Lake Champlain Basin Program (LCBP). 2017. Opportunities for Action: An Evolving Plan for the Future of the Lake Champlain Basin (OFA). Lake Champlain Basin Program, Grand Isle, VT.
Lake Champlain Basin Study. 1979. Limnology of Lake Champlain. U.S. Department of Commerce National Technical Information Service PB-295 612. January 1979. 407 pp.
New York Natural Heritage Program. 2023. New York Natural Heritage Program Databases. Albany, NY.
Nichols, W. F. 2015. Natural Freshwater Lakes and Ponds in New Hampshire: Draft Classification. NH Natural Heritage Bureau, Concord, NH.
Olivero-Sheldon, A. and M.G. Anderson. 2016. Northeast Lake and Pond Classification. The Nature Conservancy, Eastern Conservation Science, Eastern Regional Office. Boston, MA.
This guide was authored by: Gregory J. Edinger
Information for this guide was last updated on: June 4, 2021
Please cite this page as:
New York Natural Heritage Program. 2023.
Online Conservation Guide for
Summer-stratified monomictic lake.
Available from: https://guides.nynhp.org/summer-stratified-monomictic-lake/.
Accessed October 3, 2023.