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Below you will find information about the importance of watersheds, common water quality concerns, and what you can do to help protect water quality in Owasco Lake. 


Have other questions? Just ask!



What is a watershed?

As defined by the US Environmental Protection Agency (EPA), a watershed is an area of land where all of the water that is under it, or drains off of it, goes into the same place (see diagram, left). Watersheds come in all shapes and sizes and can cross county, state, and even national boundaries.  You can also visualize it as a bowl; the edges of the bowl are the edges of the watershed.  If a drop of water falls above the bowl, it makes its way to the bottom.  If the droplet falls outside the edge if the bowl, it will hit the table (or, in the watershed's case, travel to the low point of a neighboring watershed).


In the Owasco Lake Watershed, ground and surface waters eventually flow to Owasco Lake. The Owasco Lake Watershed is approximately 208 square miles, stretching into parts of Cayuga, Tompkins, and Onondaga Counties, and includes 14 towns and 2 villages.


Severe Field Erosion near Rockafeller Road

What are some conservation concerns within the Owasco Lake Watershed?

Water quality in Owasco Lake is a fundamental concern. Owasco Lake is the primary drinking water source for over 44,000 residents in central Cayuga County, including the City of Auburn and the Town of Owasco. 


Owasco Lake is also a recreational treasure for watershed residents and visitors from around New York State and beyond, for activities including boating, fishing, and hiking. Additionally, Owasco Lake and its watershed provide important habitat for a diverse array of wildlife species.


Some current water quality concerns in Owasco Lake include:​

  • Elevated levels of sediment, caused by streambank erosion and human land disturbance and habitat modification activities (e.g. construction and development).


  • Excessive nutrients, primarily phosphorus from municipal discharges, agriculture, wildlife and waterfowl, and malfunctioning septic systems. Tributary sampling results throughout the watershed for 2015 have shown elevated levels of nutrients (predominantly nitrogen and phosphorus), according to sample results provided by state certified laboratories.


  • Cyanobacteria, or Harmful Algal Blooms (HABs), which can be toxic to humans and other mammals. Collaborative monitoring efforts (NYS DEC, OWLIP, SUNY ESF, Cayuga County Health Department) during 2015 have indicated increased frequency of highly toxic shoreline HABs at many locations around the lake.


  • Fecal coliform bacteria, which can result from mammal feces in water, agricultural and stormwater runoff, and untreated human sewage. Elevated levels of E.coli in recent years have resulted in many recent beach closings at Emerson Park, located at the northern end of the lake in the Town of Owasco.

Sediment Plume on Owasco Lake

What causes a Harmful Algal Bloom (HAB)?

According to US EPA and NYS DEC, harmful algal blooms or HABs are overgrowths of cyanobacteria (formerly Blue-Green Algae) in water. Some blooms can produce dangerous toxins in fresh or saltwater, but even nontoxic blooms can negatively impact water quality. 


HABs are most typically green or blue, but can also be red or brown. They can be scummy or look like paint on the surface of the water. HABs need: sunlight, slow-moving water, nutrients (nitrogen and phosphorus). These nutrients can come from soil movement due to erosion, pesticide and herbicide use, and malfunctioning septic systems. 


Be sure to check our Algal Bloom Monitoring page for more information and current sampling results.

WQ concerns

HAB at Owasco Yacht Club

HAB at Owasco Yacht Club

What health concerns are associated with HABs?

Harmful algal blooms can:

  • Produce extremely dangerous toxins that can sicken or kill people and animals,

  • Create dead zones in the water,

  • Raise treatment costs for drinking water,

  • Hurt industries that depend on clean water.


Consuming water containing high levels of blue-green algae has been associated with damaging effects to the liver and nervous system in pets, livestock and people, according to the Cayuga County Health Department.


Direct contact or breathing airborne droplets containing high levels of blue-green algal toxins during swimming or showering can cause irritation of the skin, eyes, nose and throat, along with inflammation in the respiratory tract.

Green Algae Scum

Photo credit: NYS DEC

How does Phosphorus influence algal growth?


Phosphorus (P) is found naturally throughout lake ecosystems in open water, nearshore areas, rivers and streams, and even on land. Soil, sediment, plants, animals, animal waste, and decaying organic matter are just a few sources of Phosphorus.


Phosphorus can enter waterways intentionally and unintentially, through: runoff from residential, commercial, urban, and agricultural land, airborne particles, malfunctioning septic systems, municipal waste discharges, and fertilizers. 


Excess Phosphorus contributes to algal growth, including Harmful Algal Blooms. Some types of algae form unattractive tints, mats, slimes, or threads in water, and are often quite odorous. When algae die, the mats sink to the lake bottom and decay, creating low-oxygen conditions that can be fatal to fish and some aquatic organisms. Harmful Algal Blooms produce toxins that are harmful to both humans and wildlife.

What are buffer strips and why are they important?


A buffer strip is an area of land maintained with permanent vegetation, which helps to protect air, soil, and water quality. Buffer strips are most often found along streams, road ditches, and other waterways.


Vegetated buffers enhance stream and watershed health by: slowing runoff; enhancing water infiltration; trapping sediment, fertilizers, pesticides, pathogens, and heavy metals; and even preventing windblown soil particles from entering waterways. Furthermore, buffers stabilize streambanks against erosion due to high velocity water, and reduce stream temperatures by providing shade.


More information and design tips from

Riparian (streamside) Buffer Strip

Photo credit: University of KY

Who should I contact if I see or experience erosion on a property?


Owasco Lake Watershed Inspection Program or Cayuga Soil and Water Conservation District.

In-Stream Snag

When can I remove snags or work in protected tributaries?


A snag is a downed tree or accumulation of debris that blocks a flowing stream.


According to the Natural Resource Conservation Service (NRCS), the purpose of removing snags can range from restoring the flow and direction of a stream to minimizing blockages created by debris and ice. 


In Cayuga County, you are able to remove snags from a stream that is on your property, after July 15th*, only if it is breaking the surface of the water. You are required to get a NYS DEC and/or Army Corps of Engineers (joint) permit for in-stream work if machinery is being used. If no machinery is being used, you may remove the snag by hand and a permit is not required. If the root system of a downed tree remains in the soil, NYS DEC recommends that the roots be left in place to hold to the soil and minimize streambank erosion. 

*After July 15th most aquatic animals are in their adult forms and do not require snags for habitat.


For information on how cleaning your boat can help protect the Owasco watershed from invasive species.


How do invasive species spread, and how many different kinds are there?

Practice a clean, drain, and dry method to help protect against the spread of invasive species!

Why should I clean my boat?
What can I do to protect Owasco Lake?




  • Use dish washing detergents and car, deck, power, and boat washes that do not contain phosphorus or phosphates.​


  • Pick up pet waste and throw it in the trash.​


  • Keep grass clippings and other yard waste away from streams, stream banks, ditches, drainage ways, and the lake.​


  • Keep ashes from campfires and bonfires from entering the lake.​


  • ​Power wash boats after using in another lake. See Protect Your Waters for more details.​​


  • Have septic tanks pumped every 3-5 years.​


  • Limit the use of pesticides and herbicides.​



  • Plant the lakeshore with grasses, other perennials, and shade trees as buffers to create shade and reduce sediment and nutrients from entering the lake.​


  • Plant only native plants and do not introduce non-native species.​


  • Contact us to report any activities occurring within the watershed that may impact water quality in Owasco Lake.​


What is Lake Turnover?

As air temperatures start to cool down foreshadowing our winter months to come, the water temperatures within lakes and ponds also begin their own way of preparing for winter.


On average, summer air temperatures stay at a constant, letting stable water temperature in lakes to settle into their own groove. Consistently warm air temperatures help form a natural process called thermal stratification, sometimes referred to as, lake stratification. This process naturally creates three main layers to the body of water within a lake or pond. The temperatures of water either rise to the surface or sink to the bottom due to density changes. The three layers from warmest to coldest are as followed: epilimnion, metalimnion, and the hypolimnion.


However, cold fall air temperatures create a disturbance in the stratification process. The sudden decline in air temperatures cause the warmest layer of the lake, epilimnion, to cool down and become denser, sinking to the bottom of the lake. The water on the bottom of the lake then rises to the top, causing a cycling process called, fall lake turnover. This process can sometimes cause a disturbing sulfuric odor; this is due to the hypolimnion carrying organic nutrients to the surface once fall turnover is in process. This is actually an indicator of a healthy biome!
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