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Ashland FWCO
 Midwest Region
 Dedicated To The Tribal Aquaculture ProgramImage of fish jumping.
    March
        2002-Volume 39

**Administrative
        Coordinator:
        Frank G. Stone 
        (715-682-6185) Ext.
        202
        U.S. Fish and
        Wildlife Service
        Email: 
        [email protected]**
      **Edited
        By:
        Elizabeth W. Greiff 
        (715-349-2195) Ext. 141
        St. Croix Tribal Nat. Res. Depart.
        Email:**

**[email protected]** Topics
Of Interest: Calculating
Area and Volume of Ponds and Tanks Calculating AreaSquare or Rectangular Ponds Other Pond ShapesIrregularly Shaped PondsCalculating VolumeTanksPondsConversion Tables  Calculating
Area and Volume of Ponds and Tanks By:  Michael P. Masser and John W. Jensen, Alabama Cooperative
Extension Service, August 1991 Good fish farm managers must know the area and volume of all ponds and tanks.
Exact measurement of area and volume is essential in order to calculate stocking
rates and chemical applications.  Stocking fish into a pond of uncertain
area can result in poor production, more disease and possibly death. Chemical
treatments can be ineffective if volume/area is underestimated and potentially
lethal if it is overestimated.  Measurements and calculations described in
this publication can be made in either English or metric units. All examples are
given in English units. Conversion tables are also provided for those who wish to use metric units.  Calculating Area Surface area calculation is an essential first step. Pond stocking rates,
liming rates and other important management decisions are based on surface
area.  An error in calculating surface area will inevitably lead to other
problems.  Measure distances accurately, calculate area and double check
all calculations.  You may not need to measure pond area yourself, the contractor who built the pond should have accurate records.
The county field office of the U.S. Department of Agriculture Natural Resources Conservation
Service (NRCS) assists with the construction of many ponds and has engineering
records on ponds in each county.  Also, the county offices of the NRCS
and the USDA Agricultural Stabilization and Conservation Service (ASCS) have
aerial photos from which pond area can be estimated. Surveying ponds using a transit is the most accurate way to determine area.
Less accurate but acceptable methods of measuring pond area are chaining and
pacing.  Inaccuracies in these methods come from mismeasurements and
measurement over uneven/sloping terrain. Measurements made on flat or level
areas are the most accurate. Chaining uses a measuring tape or other instrument of known length. 
Stakes are placed at each end of the tape. The stakes are used to set or locate
the starting point for each progressive measurement and to maintain an exact
count on the number of times the tape was moved. Sight down the stakes to keep
the measurement in a straight line. The number of times the tape was moved
multiplied by the length of the tape equals total distance. Pacing uses the average distance of a persons pace or stride. To determine
your pace length, measure a 100-foot distance and pace it, counting the number
of strides.  Pace in a comfortable and natural manner. Repeat the procedure
several times and get an average distance for your stride. For example, if it took you 38, 39 and 40 paces to walk a measured 100-foot
straight line then the average was 39 paces (38 + 39 + 40  3).  To get
the length of your average pace divide 100 feet by 39 paces (100 ft  39 paces
= 2.56 feet per pace). Now, whenever you pace a distance, simply multiply the
number of paces by 2.56 to get the distance.  It is a good idea to always pace a distance more than once and
average the
number of paces.  The formula for calculating
distances from pacing is: Distance (ft) = Total Number of Paces x Length of Average Pace Square or Rectangular Ponds Ponds built in square or rectangular shapes are the most easily
measured.  Square and rectangular areas are determined by multiplying
length by width. Figure 1 illustrates some typical shapes and sizes of
ponds. Figure 1. Figure 1.   Rectangular pond areas are estimated by the formula: Area = length x width
Area of the rectangular pond in Figure 1 is:
Area = 500x 150= 75,000 square feet To convert from square feet (ft2) to acres, divide by 43,560 (from
Table 1). Area = 75,000 43,560= 1.72 or 1.7 acres In this example the area of the rectangular pond is 75,000 square feet
or approximately 1.7 acres.  Areas of ponds which are almost square or
rectangular can be estimated by calculating average length and width
measurements.  If we designate the lengths as A and B, and the width as Y
and Z then the formula for the area is:Area Formula  For example, an almost rectangular pond that is 470 feet on one side and 525
feet on the other long side, and 140 feet on one end and 162 feet on the other
end, has an area of 75,123 ((470 + 525  2) x (140 + 162  2)) square feet or
1.72 acres.  Other Pond Shapes Other formulas are used to calculate ponds that are circular and triangular.  Even if your pond is not an exact shape, it maybe possible to
get a reasonable estimate of its area by using one or a combination of these
formulas.  Circular pond areas are estimated by the formula: Area = 3.14 x radius2
(Radius is one-half the diameter) For example, a circular pond with a radius of 75 feet has an area of 17,663
square feet (3.14 x 75 x 75) or 0.4 acres.  The radius can be measured
directly or the diameter can be divided by 2. A measurement of the diameter in
several directions will help to determine if the pond is truly circular. 
Triangular pond areas are estimated by one of two formulas depending on
whether the triangle has a square or 90 angle for one of its corners.  If a
90 angle is present the formula is: Area =  x length x width For example, a triangular pond with a length of 250 feet and a width of 220
feet has an area of 27,500 square feet (250 x 220  2) or 0.63 acres. It is
important to remember that the longest side (the hypotenuse) is not needed for
the calculation, instead the two sides that touch the 90 angle are used. 
If no 90 angle is present and the sides are unequal, the formula is:  Formula  ... and A, B and C are the lengths of the sides.  For example, a triangular pond
with three sides of 80, 90 and 130 feet has an area of 3,549.6 square feet
(where S = 150); and Formula   Irregularly Shaped Ponds Many ponds in the Southeast are watershed ponds that have been built by
damming valleys. These ponds are usually irregular in shape.  Check first
with your county NRCS office for records on your pond, or for aerial photos in
the NRCS or ASCS office. If no good records exist then a reasonable estimate can
be made by chaining or pacing off the pond margins and using the following
procedures to calculate area. 1.  Draw the general shape of the pond on paper (graph paper works
  best).
  2.  Draw a rectangle on the pond shape that would approximate the area
  of the pond if some water was eliminated and placed onto an equal amount of
  land. This will give you a rectangle on which to base the calculation of
  area (See Figure 2 below).
  3.  Mark the corners of the rectangle (from the drawing) on the
  ground around the pond and chain or pace its length and width. For example, a
  length of 350 paces and a width of 125 paces would be equal to 896 feet (350
  paces x 2.56 feet/pace [pace length, from above]) by 320 feet.
  4.  Multiply the length times width (see example above) to get the
  approximate pond area. For example, 896 feet x 320 feet =286,720 square feet
  or 6.58 acres (286,720  43,560). Figure 2. Figure 2.  It is a good idea to repeat this procedure two or three times and compare
your results. You may want to average these results if they differ.  If a
single rectangle does not fit the pond drawing then try to fit some combination
of rectangles, circles, and/or triangles. If some combination seems to fit,
then calculate the areas of the different shapes, and add the corresponding
areas together to get the total pond area.   Calculating Volume Volume measurements are needed to calculate the proper concentration of most
chemicals which are applied to water and to calculate holding or transport
densities.  Tanks Most tanks used for holding and transporting fish are rectangular. 
Rectangular volume is calculated by the formula: Volume = length x width x depth When measuring a tank, take inside measurements of length and width and the
depth at the appropriate water level. If a standpipe or other type of overflow
drain is present, then the height to the overflow should be the depth
measurement. 
If the bottom of the tank is sloped toward the drain an average depth
measurement should be used. To get average depth of the tank, take three
measurements: at the shallow end, in the middle, and at the overflow. Add these
depths together and divide the total by 3. For example, a rectangular tank, without a sloping bottom (see Figure 3), has a measured inside width of 36 inches, a length of 72 inches and a
depth at the standpipe overflow of 24 inches. The calculated volume is 62,208
cubic inches (36 x 72 x 24). Figure 3. Figure 3.  In many cases it will be necessary to convert cubic inches (in 3)
to either cubic feet (ft3) or gallons.  Table 4 gives simple
ways to make these conversions. Cubic inches are converted to cubic feet by
multiplying by 0.000579 (or by dividing by 1728). Cubic inches are converted
to gallons by multiplying by 0.00433 (or by dividing by 231).  A volume of
62,208 in3 is the same as 36 ft3 (62,208 x 0.000579 or 62,208 + 1728) and 269
gallons (62,208 x 0.00433 or 62,208  231). Circular tank volume (Figure
4) is determined by the formula: Volume = 3.14 x radius2x depth Figure 4. Figure 4.  The radius is measured as  the inside diameter of the tank. The radius is
squared or multiplied by itself.  For example, a circular tank with an
inside diameter of 72 inches and a standpipe depth of 24 inches has a volume of
97,667 cubic inches (3.14 x 36 x 36 x 24).  Using Table 4 the volume can be
converted into cubic feet (97,666.56  1728 = 56.52) or gallons (97,666.56 
231= 422.8). Ponds Pond volumes can be calculated using the formula: Volume = surface area x average depth Calculating surface area was presented in the first section of this fact
sheet. Calculate the average depth by measuring the depth at intervals around
the pond. A boat and weighted cord (marked in feet) are used to take depth
measurements.  Measurements can be done in a grid pattern or in a
crisscross
pattern.  The number of depth measurements taken affects the accuracy of the estimate.
Increasing the number of measurements increases the accuracy, so take as many
measurements as possible. Record all depth measurements, add them together and divide the total by the
number of measurements taken. For example, in Figure 5, the sum of the depth
measurements totals 93 feet. Divide 93 by 16 (the number of measurements) to
get an average depth of 5.8 feet. The pond volume in this example (taking the
surface area as 6.58 acres from previous example) would be 38.16 acre-feet
(6.58 acres x 5.8 feet). Figure 5. Figure 5.  Keep good records of your pond area(s) and volume(s). Do not rely on your
memory. The water level and volume in watershed ponds may vary from season to
season with rainfall, evaporation, siltation and other factors. Pond managers
should calculate the volume of ponds at different water levels, 
 so chemical
treatments can be applied properly under any condition.  Do not guess the area or volume of your pond because the consequences could
be costly.  Conversion Tables Table 1.  Useful Conversion Factors1 acre
      = 43,560 square feet
        = 4,840 square yards
        = 235.4 feet (diameter of circular tank)
        = 208.71  feet/side (square tank)1 acre-foot (1 acre that is 1 foot deep)
      = 43,560 cubic feet
        = 325,850 gallons
        = 2,718,144 pounds1 cubic foot
      = 7.48 gallons
        = 1,728 cubic inches
        = 62.43 pounds1 gallon
      = 8.34 pounds1 quart
      = 4 cups
        = 32 fluid ounces1 pint
      = 2 cups
        = 16 fluid ounces1 cup
      = 8 fluid ounces
        = 8.344 ounces1 fluid ounce
      = 1.043 ounces
  Table 2.  Conversions in LengthFrom
      Toinches (in)
      feet (ft)
      yard (yd)
      centimeter (cm)
      meter (m)inches
      1
      0.0833
      0.0278
      2.540
      0.0254feet
      12
      1
      0.3333
      30.48
      0.3048yards
      36
      3
      1
      91.44
      0.9144centimeter
      0.3937
      0.0328
      0.0109
      1
      100meter
      39.37
      3.281
      1.0936
      100
      1
 Table 3.  Conversion in WeightFrom
      Toounce (oz)
    pound (lb)
    gram (g)
    kilogram (kg)ounces
    1
    0.0625
    28.35
    0.0284pound
    16
    1
    453.6
    0.4536gram
    0.0353
    0.0022
    1
    0.001kilogram
    35.27
    2.205
    1000
    1
Table 4.  Conversion in VolumeFrom
      Toin3
    ft3
    fluid oz
    gallon
    cm3
    liter
    meter3in3
    1
    0.000579
    0.5541
    0.00433
    16.39
    0.0164
    0.00001ft3
    1,728
    1
    957.5
    7.481
    0.000283
    28.32
    0.0283fluid oz
    1.805
    0.00104
    1
    0.0078
    29.57
    0.0296
    0.00002gallon
    231.0
    0.1337
    128
    1
    3,785
    3.785
    0.0038cm3
    0.061
    0.0000353
    0.0338
    0.000264
    1
    0.001
    0.000001liter
    60.98
    0.0353
    33.81
    0.2642
    1,000
    1
    0.001meter3
    610,000
    5.31
    33,800
    264.2
    1,000,000
    1,000
    1
Table 5.  Conversion of Various Volumes to
        Attain One Part Per MillionAmount active ingredient
      Unit of volume2.71 pounds
    acre-foot1.235 grams
    acre-foot1.24 kilograms
    acre-foot0.0283 grams
    cubic foot1 milligram
    liter8.34 pounds
    million gallons1 gram
    cubic meter0.0038 grams
    gallon3.8 grams
    thousand gallons
Table 6.  Conversion for Parts Per Million in
        Proportion and PercentParts Per Million
      Proportion
      Percent0.1
      1:10,000,000
      0.000010.5
      1:2,000,000
      0.000051.0
      1:1,000,000
      0.00012.0
      1:500,000
      0.00023.0
      1:333,333
      0.00035.0
      1:200,000
      0.00057.0
      1:142,857
      0.000710.0
      1:100,000
      0.00115.0
      1:66,667
      0.001525.0
      1:40,000
      0.002550.0
      1:20,000
      0.005100.0
      1:10,000
      0.01200.0
      1:5,000
      0.02250.0
      1:4,000
      0.025500.0
      1:2,000
      0.051,550.0
      1:645
      0.1555,000.0
      1:200
      0.510,000.0
      1:100
      1.0

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