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Calcimator

Water Rights Calculator

Calculate acre-feet allocation, required diversion rate, and duty of water for irrigation water rights.

Inputs

%

Results

Gross need (acre-ft)

150

Required diversion (CFS)

0.5

Net need (acre-ft)120
Required diversion (GPM)226
Serviceable acres40
Right adequacy (%)100
Gross volume (gallons)48,877,650
Annual water cost ($)$3,750.00
How to Use This Calculator
  1. Enter irrigated acres and your water right's duty of water in acre-feet per acre.
  2. Set irrigation season length in days and conveyance loss percentage for your delivery system.
  3. Enter water cost per acre-foot from your district or ditch company.
  4. Optionally enter your decreed diversion rate in CFS to check adequacy.
  5. Review Gross need (acre-ft), Required diversion (CFS/GPM), and Annual water cost to verify your water right covers your needs.

How the result changes with Irrigated acres

Irrigated acresGross need (acre-ft)Required diversion (CFS)
10,00037,500126.04
35,000131,250441.14
65,000243,750819.26
90,000337,5001,134.36

What each input means

Irrigated acres
Total irrigated acreage under the water right.
Duty of water (AF/acre)
Acre-feet per acre per season. Varies by crop and region: 2-4 typical.
Irrigation season (days)
Length of the irrigation season in days.
Conveyance loss (%)
Water lost in canals/ditches before reaching field. Lined=5-10%, unlined=20-40%.
Water right (CFS)
Your decreed diversion rate in cubic feet per second. Leave 0 to calculate requirement.
Water cost ($/AF)
Cost per acre-foot from your water district or ditch company.

What each result means

Net need (acre-ft)
Net water needed at the field based on duty of water.
Gross need (acre-ft)
Total diversion needed including conveyance losses.
Required diversion (CFS)
Continuous diversion rate needed over the irrigation season.
Required diversion (GPM)
Diversion rate in gallons per minute.
Serviceable acres
Acres your water right can serve (based on entered or calculated CFS).
Right adequacy (%)
Percentage of water need covered by the water right.
Gross volume (gallons)
Total seasonal volume in gallons.
Annual water cost ($)
Estimated annual cost based on gross allocation.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Irrigated acres = 40, Duty of water (AF/acre) = 3, Irrigation season (days) = 150, Conveyance loss (%) = 20 = 6 input(s) provided
  2. Calculate Gross need
    Gross need = netAllocationAF * conveyanceMultiplier
    150 = 150
  3. Calculate Required diversion
    Required diversion = grossAllocationAF / (irrigationSeasonDays * 1.9835)
    0.5 = 0.5
  4. Calculate Net need
    Net need = irrigatedAcres * dutyOfWater
    120 = 120
  5. Calculate Required diversion
    Required diversion = requiredCFS * 448.83
    226 = 226

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