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Lake County, Ohio - Soil & Water Conservation District

Pond Management

    Pond Management

     Commonly asked questions concerning pond site evaluation and pond management

    Where can I place a pond?

        There are many considerations when placing a pond, including soil type, watershed, cost, safety, longevity, and intended use.  Ponds should be placed at least 100 feet from a septic field, and ideally, they would be in an area that is not paved, farmed or grazed as all of these can diminish water quality. 

    How big should my pond be?

         This varies somewhat with the land use.  The chart below is a good start for estimating area.  Cost is also an important factor, as is intended use.  If you intend to stock fish, then at least 25% of the surface area should be over 8 feet deep.  This allows the fish to over winter without running out of oxygen.  The minimum size for fishing, swimming or supplying water is 1/4 acre.

    Pond Size

    Watershed Size

    0.5 acre

    3 to 20 acres

    1 acre

    6 to 40 acres

    2 acre 12 to 80 acres
    3 acre 18 to 120 acres

     

    How do I determine if my location is ideal for a pond?

         Will the pond hold water?  Tight, clayey, poorly drained soils are well suited for ponds.  Sands and gravel are poor soils for ponds.  These soils are dependent on the groundwater level for a pond.   For general backyard ponds, clayey, poorly drained soils are ideal.  The best way to be satisfied with the soils at the site is to test them.  Digging 4 to 5 test holes with a backhoe in the location of the pond that are at least 1 to 2 feet deeper than the deepest portion on the pond will enable a soil consultant to "read" the soils for their compatibility with a pond.  It is best to go deeper during the test hole phase than to start digging the pond and find a sand or gravel layer 6 inches below your deepest part while building a pond!

    What should I consider in regards to my neighbors and flooding?

         Water should not flood upstream of the pond and cause problems with your neighbor.  Even during a heavy thunderstorm, all the flood water should be contained on your property.  The over flow water should leave your property at the same place as before building the pond.  What is downstream?   Is there a house or major road?  One should look 1/2 to 1 mile downstream, not just over the property line!

    How do I know if I'm ready to start digging?

         Can you answer the following questions:  

    • What are my property lines?  

    • Are there any underground utilities in the area?  

    • Gas, water, sewer, electric, telephone, cable?  

    • Can I get machinery into the area to do the necessary work?  

    • How high is my dam?  

    • Do I need a permit?  

    Other issues may need to be addressed also BEFORE you start to build!

    The Lake County Soil and Water Conservation District can help answer some of your questions and concerns. The District has literature on pond design and construction and the District offers technical assistance through the Natural Resource Conservation Service. Call the District for more information.

    Why are all my fish dead?  What is a fish kill?

            The most common cause of fish kill in Ohio ponds is suffocation due to lack of oxygen. This can occur due to several different reasons. Decomposition of organic matter (dead vegetation) can lead to oxygen depletion in the water column. As aquatic vegetation and organic matter decompose, oxygen is used by decomposers to breakdown the matter. During the summer months, decomposition may use up what little oxygen is in the water column, resulting in an insufficient amount for fish.

            Another cause of oxygen depletion is inversion or "turn over" of your pond. During late spring and summer your pond develops layers as a result of temperature and density differences. Rapid warming in the upper level of the pond results in less dense water, which has a lower oxygen holding capacity as well. Warmer water holds less oxygen than cooler water. However, with photosynthesis and oxygen exchange at the water surface - atmosphere interface - enough oxygen is provided for the minimum needs for the fish. The cooler layer of water in the bottom of the pond has the potential to hold more oxygen, but due to the lack of photosynthesis and the decomposition of organic matter there is actually less dissolved oxygen in the lower level compared to the top layer. When a turnover of the layers occurs due to strong winds, a rapid temperature change, or a inflow of a large amount of water, the cooler (less oxygenated) layer goes to the top and the warmer (more oxygenated) layer goes to the bottom. Fish like to stay near the surface, so when the cooler oxygen deficient water becomes the top layer the fish experience suffocation.

         Finally, a fish kill can occur during long cold spells as ice develops on the surface of the pond.  This ice layer acts as a lid and prevents oxygen from entering the water from the air.  Decreased light infiltration also reduces photosynthesis in plants.  Sometimes dead fish will appear in great quantities in the spring, but other times they remain submerged and unnoticed.  Pond depth is an important factor, a stocked fish pond should be at least 8 feet deep over at least 25% of the surface area.  Installing and running an aerator in the winter helps to keep an opening on the surface of the water.  Simply cutting a hole in the ice will also work, especially in a smaller pond.

    What can I do to prevent a fish kill?

            ~An algae management plan can help control large accumulations of organic matter, which use a large amount of oxygen when it decomposes.

            ~Use of an aerator will enable oxygen to diffuse into the water column and keep the water well oxygenated.  It will also keep an area from icing over in the winter

    How do I calculate pond size?

    Determining Surface Area of your pond:

    • Circular shaped pond: -measure the total distance around the pond surface in feet and multiply this number by itself and divide by 547,560

    • Rectangular shaped pond: -measure the length of one side and the width of one side and multiple these number together and divide by 43,560 (43,560 ft.2/acre)

    Determining Average Depth of your pond:

    • Take depth measurements uniformly spaced over your entire pond surface. Add the measurements together and divide by the total number of measurements taken.

    Determining Acre Feet of your pond:

    • Multiply the surface area (acres) by the average depth (feet) to calculate the volume (acre-feet).   One acre-foot equals 325,850 gallons of water.