Assessing Your Pond

Temperature | Depth | Volume
Water Quality | Survey/Data Sheet


Use a thermometer to measure the surface water temperature of the pond. The water temperature at the deepest part of the pond can be measured using a thermometer attached to a weighted rope. Lower the device until it is just off the bottom and leave it suspended there for approximately 5 minutes. Raise the device quickly through the water column, remove the thermometer and check the temperature immediately. Thermometers can be purchased from local hardware stores, aquarium shops, or various equipment supply companies.


Water depth is best measured from a boat, along 2 perpendicular transects in the pond. Use a weighted line to measure depth at 5 points along one transect and at 5 points along the other transect. Add these depth measurements and divide by the total number of measurements to calculate the average depth. To obtain the best depth estimate, the larger the pond, the more measurements you should take. It is also effective to measure pond depth during the winter by augering holes in the ice along transects at regular intervals.

For further information on calculating pond depth and volume, see:

Calculating Water Volume in Ponds. "Commercial Farm Pond Management" series fact sheet. Cornell Cooperative Extension.


There are several ways to estimate the volume of your pond. Generally, the following calculations will give you a reasonable estimate of the number of gallons in your pond.

If you have rectangular pond:

Length  x  Width  x  Average Depth (see above)= ___ft cubed

To convert from cubic feet to gallons divide by 0.134

ft cubed / 0.134 ft cubed per gallon = ___gal

If you have a circular pond:

3.14  x  radius of your pond squared  x  average depth = ___ft cubed

Use the same conversion from cubic feet to gallons:

ft cubed / 0.134 ft cubed per gallon = ___gal


If your pond basin in mostly conical in shape you can use the formula for the volume of a cone:

1.047  x  radius squared  x  maximum depth = ___ft cubed

Water Quality

Water clarity can be influenced by many variables such as turbidity of sediments and algal density in pond ecosystems. Monitoring the water clarity in your pond can be very interesting over the course of the year. Besides qualitative methods which are informative, the standard method for measuring water transparency is to use a secchi disk. Secchi disks are available for purchase from various equipment supply companies.

To obtain a secchi reading, Lower the disk into the water slowly and stop just when it disappears from sight. Record this depth. Slowly raise the disk back up until it comes into view, and then stop. Record this depth. The secchi disk reading, as a measure of transparency, is an average of these two measurements.

Pond Use Survey and Data Sheet Click here to open or save this file which contains a data sheet used by pond owners as part of the Pond Owner's Cooperator's Program.

Click here for more information about participating in the Pond Owner's Cooperator Program.
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