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Worksheet Grade 9 Social Studies & Civics

Antelope Wash Water Rights: A Prior Appropriation Worksheet

Grade 9 worksheet where students convert two fictional farms' acre-foot water rights to gallons and apply prior appropriation to a drought-year shortage.

Objectives

  1. Students will explain the prior appropriation doctrine and the rule 'first in time, first in right.'
  2. Students will convert water rights between acre-feet and gallons using a given conversion factor.
  3. Students will evaluate who benefits and who is disadvantaged when a shared river's flow drops.

Vocabulary

Prior appropriation
The Western water rule of first in time, first in right. Whoever started using water first has the strongest claim, and in a shortage the newest users are cut off first.
Acre-foot
The amount of water it takes to cover one acre of land, about the size of a football field, one foot deep. Western states use acre-feet to measure large amounts of water.

Also: senior right, junior right

Teacher overview

Two fictional farms, Delgado Farm and Foss Farm, draw irrigation water from the fictional Antelope Wash under a water-rights system called prior appropriation, common across the western United States. Under this system, the farm with the older ("senior") right is guaranteed its full water amount before any water goes to a farm with a newer ("junior") right, no matter how the two farms' needs compare in a given year. This worksheet has students convert each farm's right from acre-feet, the unit water rights are usually measured in, into gallons, and then apply the prior-appropriation rule to a drought year in which the river cannot supply both farms in full. A common misconception is that a shortage gets shared evenly between rights holders; prior appropriation does the opposite, protecting the senior right completely and forcing the entire shortfall onto junior rights, which this worksheet's numbers are built to make visible.

Antelope Wash Water Rights: A Prior Appropriation Worksheet — Grade 9 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Worksheet

Use these facts for every item below.

  • Delgado Farm holds a senior water right of 400 acre-feet per year on Antelope Wash, established in 1908.
  • Foss Farm holds a junior water right of 250 acre-feet per year on Antelope Wash, established in 1961.
  • One acre-foot equals 325,851 gallons.
  • This year, a drought has reduced Antelope Wash's flow so that only 500 acre-feet total are available for both farms combined.
  1. In one to two sentences, explain what "prior appropriation" means, using the phrase "first in time, first in right."
  2. In a normal year, Antelope Wash supplies enough water to fully meet both farms' rights. What is the combined total water right, in acre-feet, held by the two farms together?
  3. Convert Delgado Farm's 400-acre-foot right to gallons.
  4. Convert Foss Farm's 250-acre-foot right to gallons.
  5. This drought year, only 500 acre-feet total are available. Under prior appropriation, whose right is filled first, and how many acre-feet remain for the other farm after that right is filled?
  6. Calculate how many acre-feet Foss Farm actually receives this drought year, and express that amount as a percent of Foss Farm's full 250-acre-foot right.
  7. Convert the acre-feet Foss Farm actually receives this year (from item 5) to gallons.
  8. Calculate Foss Farm's shortfall this year in acre-feet (the difference between its full right and what it actually receives), then convert that shortfall to gallons.
  9. Producing a pound of wheat takes roughly 220 gallons of water, while producing a pound of beef takes roughly 1,800 gallons. Using Foss Farm's actual gallons received this year (item 7), explain in two to three sentences why the same shortfall in acre-feet would affect a wheat farm differently than a cattle operation of the same size.
  10. Prior appropriation protects whichever right is oldest during a drought. Identify one group who benefits from this system and one group who is placed at a disadvantage, and explain why in one to two sentences each.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Prior appropriation means the oldest water right is filled first.
    Under "first in time, first in right," the farm that established its water right earliest (Delgado Farm, 1908) is guaranteed its full allocation before any water goes to a farm with a newer right (Foss Farm, 1961), regardless of each farm's size or need that year.
  2. Answer: 650 acre-feet.
    400 acre-feet (Delgado) + 250 acre-feet (Foss) = 650 acre-feet.
  3. Answer: 130,340,400 gallons.
    400 acre-feet x 325,851 gallons/acre-foot = 130,340,400 gallons.
  4. Answer: 81,462,750 gallons.
    250 acre-feet x 325,851 gallons/acre-foot = 81,462,750 gallons.
  5. Answer: Delgado Farm's right is filled first, leaving 100 acre-feet for Foss Farm.
    Delgado Farm's senior right uses 400 of the 500 available acre-feet, leaving 500 - 400 = 100 acre-feet for Foss Farm's junior right.
  6. Answer: 40 percent.
    Foss Farm receives 100 of its 250-acre-foot right. 100 / 250 = 0.40, or 40 percent.
  7. Answer: 32,585,100 gallons.
    100 acre-feet x 325,851 gallons/acre-foot = 32,585,100 gallons.
  8. Answer: 150 acre-feet, or 48,877,650 gallons.
    Shortfall: 250 - 100 = 150 acre-feet. In gallons: 150 x 325,851 = 48,877,650 gallons.
  9. Answer: Answers will vary but should reason quantitatively from item 7's total.
    Foss Farm's roughly 32.6 million gallons this year could grow a substantial wheat crop at about 220 gallons per pound, since 32,585,100 / 220 = about 148,114 pounds of wheat. The same water would support far less beef production, since 32,585,100 / 1,800 = about 18,103 pounds, showing that the same volume of water yields far less beef than wheat, so a cattle operation is left with much less food output after the shortfall, even though both lose the same 60 percent of their water. Teachers may note that both per-pound figures are global averages that include rainwater, and most of the beef figure is rainwater used by pasture and feed crops, so this comparison with irrigation water is approximate.
  10. Answer: Answers will vary; a reasonable response names a beneficiary and a disadvantaged party with a clear reason.
    Senior right holders like Delgado Farm benefit because their water supply stays protected even in a severe drought. Junior right holders like Foss Farm are disadvantaged because they absorb the entire shortage in a bad year, even though the drought is not something either farm caused.

Differentiation

Support (below grade level)

Provide a pre-filled unit-conversion chart showing "acre-feet x 325,851 = gallons" as a labeled arrow rule, and allow students to complete items 3, 4, and 7 with a calculator, checking only that they multiplied the correct two numbers. Work through item 5 together as a class before students attempt items 6 through 8 independently.

Extension (above grade level)

Ask students to calculate, using only the numbers provided on this worksheet, what percent of Antelope Wash's drought-year total (500 acre-feet) each farm actually receives, then to propose and justify, in a short paragraph, an alternative rule that would split the shortage differently than prior appropriation does.

ELL supports

Pre-teach "senior," "junior," "appropriation," and "shortfall" with a simple visual: two labeled buckets of different sizes (Delgado larger, Foss smaller) next to a shrinking river icon. Allow items 1 and 10 to be answered with short phrases or a labeled diagram instead of full sentences where the standard permits.