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Pond acre-feet and treatment calculator
People overestimate pond size. Measure it. Average depth, not the deep hole.
Acre-feet is surface acres times average depth in feet. That volume drives how much water you have and how much product the label says to put in. On this Huntsville place the pond we dug is the same one in the family photos — measure the real average depth or the treatment math is fiction. See also livestock water and Huntsville frost dates.
How to measure a pond
Walk length and width, or pace them. Average depth is not the hole by the dam — it’s a honest guess across the whole pond, including the skinny end. Surface acres × that average depth = acre-feet. People blow treatments by measuring the deep spot and calling it the pond.
Worked example: 200 × 80 × 6
Illustrative only — not a survey of a pond on this place. The form opens on a rectangle 200 ft by 80 ft with average depth 6 ft. Hit Calculate.
Surface is 200 × 80 = 16,000 square feet. Divide by 43,560 and the screen shows 0.37 surface acres (16,000 ÷ 43,560 is about 0.367). Acre-feet is that surface times depth: about 0.367 × 6 = 2.20 acre-feet. Gallons are acre-feet × 325,851, which rounds to 718,129 gallons. One acre-foot is the unit in the middle of that chain.
If you already know surface acres, leave Shape on Rectangle and type them in Or surface acres. That box overrides length and width. Circle uses diameter (π times radius squared) and ignores the acres box. Oval uses length and width (π × length/2 × width/2). Leave the deepest sounding out of Average depth. Example only — measure your pond and run your own inputs. The stations belong on the pond measure sheet.
How to estimate average depth
Take several depth readings from the bank, a boat, or another method you can do safely. Spread them across the basin, including the shallow edges and the skinny end, then average the readings. That average is a planning estimate of the whole pond, not a survey.
The hole by the dam is not the pond. One deep reading overstates the water and, if a label rate is in the form, the product amount that follows. An irregular shoreline gets the shape that best matches the surface, or surface acres you measured yourself. Stay inside safe bank or boat conditions while you collect the number.
A label rate is not a recommendation
If the label states a rate per acre-foot, type that number in the label box. The calculator multiplies it by the acre-feet it just figured. If the label uses gallons or another unit, follow that label’s unit and its own conversion. Product choice stays on the label. This page does not pick copper, dye, herbicide, or a dose.
Permitted use, and any livestock, fish, or water-use limits, belong on the product label and with qualified local advice. Pond volume is stored water. It is not livestock demand and it is not pump sizing. Animal need is the livestock water calculator. More blank sheets are with the field sheets.
Questions
What is an acre-foot of water?
One acre of surface covered one foot deep — about 325,851 gallons.
Why average depth instead of the deep end?
Treatments and volume need the whole basin. The deep hole alone overstates what is out there.
Can I use this for chemical rate?
Yes if your label rates by acre-foot or gallons. Always follow the product label.
How do I calculate pond gallons?
Find surface acres, estimate the pond’s average depth, multiply for acre-feet, then multiply acre-feet by about 325,851 gallons. Use the calculator. The deepest spot is not a stand-in for average depth.
What if my pond is an irregular shape?
Choose the closest shape for a planning estimate, or figure surface acres yourself and enter those acres on Rectangle. Measure the whole surface, not only the widest or deepest section.
How many depth readings should I take?
Take enough readings to represent the shallow edges, the middle, and the deeper basin, and only as many as you can take safely. One deep-hole reading overstates the volume.
How do I use a product rate per acre-foot?
Enter the rate exactly as the product label states. The calculator multiplies it by acre-feet. Confirm the label’s unit, permitted use, and water-use restrictions. This page does not recommend a chemical.
Is pond volume the same as livestock-water supply?
No. Pond volume is stored-water math. Animal demand, access, drought, water quality, and tank or pump capacity are separate questions. Use the livestock water calculator for demand.
Does average depth change treatment math?
Yes. Acre-feet and gallons are surface area times average depth, so using only the deepest hole can overstate the water and any label-based product amount.
Planning only. Volume = surface acres × average depth. 1 acre-foot ≈ 325,851 gal. We do not recommend a chemical. Rate comes off your label. TAMU PondCalc is the full pond-management app.
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