Classroom activity Grade 8 Science

Vesper Valley Drought: A Reservoir Allocation Simulation

A grade 8 science simulation where student teams negotiate how to split a shrinking reservoir among a city, farms, and a river across four drought years.

Grade: Grade 8
Subject: Science
Material: Classroom activity
Time: 45 min
Prep: Low prep
Materials: Three role cards listing each team's yearly need (see step 2), Reservoir tracking sheet or board space, Counters or chips to represent acre-feet (optional)

Standards

MS-ESS3-4 NGSS

Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth's systems.

How this material aligns: Teams argue from the shrinking-supply data for how population and consumption strain the reservoir, constructing evidence-based claims about resource use exactly as this standard requires across the four rounds.

All materials for MS-ESS3-4 →

MS-LS2-1 NGSS

Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.

How this material aligns: The environment team uses minimum-flow data to argue how falling river water threatens the fish population, the resource-availability effect on organisms this standard names.

All materials for MS-LS2-1 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will negotiate an allocation of a shrinking water supply among competing users.
Students will argue from data how a multi-year drought forces trade-offs among a city, farms, and a river.

Vocabulary

Reservoir: A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.
Drought: A long stretch of drier-than-normal weather that leaves too little water for people, farms, and nature. Droughts build slowly and can last for years.

Also: allocation, minimum flow, trade-off

Teacher overview

This is a role-play negotiation for a class working in three teams. The fictional Vesper Valley depends on one reservoir, and over four simulated years a drought steadily cuts how much water it holds. Each team represents one user, the city water utility, the valley's farms, or the river ecosystem, and every round the teams must agree on how to split a supply that keeps shrinking below what everyone wants. The negotiation itself teaches the concept, because students face the same trade-offs a real water board confronts when demand stays high while the supply keeps falling.

Activity Directions

Before class, make three role cards, each giving one team's name and yearly need from step 2, and prepare a place to track the reservoir supply each year, either on the board or with counters where each counter stands for a set number of acre-feet. Divide the class into three teams: City, Farms, and Environment. Larger classes can run two parallel valleys.
Give each team its role card. The City needs 3,000 acre-feet a year for homes and businesses. The Farms need 4,000 acre-feet to water their crops. The Environment team speaks for the river and its fish, which need at least 1,500 acre-feet of flow to stay healthy. Point out that the three demands total 8,500 acre-feet.
Announce Year 1. Suppose the reservoir can supply 9,000 acre-feet this year. Give the teams three minutes to claim their share. Because supply is above total demand, they should reach a full allocation quickly. Record what each team receives.
Announce Year 2, a drier year with only 6,500 acre-feet available. Now the teams cannot all get what they asked for. Give them five minutes to negotiate an allocation that uses no more than the available water, and record the result and each team's argument.
Announce Year 3, with only 4,000 acre-feet available, and Year 4, with only 2,500 acre-feet. Run each as its own negotiation round. In these rounds teams should propose cuts, conservation, or priorities, and must justify their claims with reasons, not just demands.
If a round ends without agreement, the teacher acts as the water board and imposes an allocation, explaining the reasoning. Track the fish population as a simple status: healthy if the Environment team gets at least 1,500 acre-feet, stressed if it gets less, and at risk if it gets less than half.
End the simulation after Year 4. Gather the class and use the debrief questions below.
Debrief questions to discuss as a class: (a) Which year was the hardest to allocate, and why? (b) What trade-offs did each team have to accept as the drought deepened? (c) What happened to the river's fish, and what does that show about resource availability? (d) What could Vesper Valley do before the next drought to make these choices less painful?

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

Answer Key

Items 1 through 4 answer debrief questions (a) through (d) in step 8.

Answer: Year 4 was hardest. With only 2,500 acre-feet against 8,500 acre-feet of total demand, the teams could meet less than a third of what everyone wanted, forcing deep cuts to at least two users.
Answer: Each team gave up something. The City likely accepted conservation limits, the Farms likely fallowed fields or lost crops, and the Environment often took less than the 1,500 acre-feet the fish needed. Accept answers that name a specific concession per team.
Answer: The fish population fell to stressed or at risk in the dry years whenever river flow dropped below 1,500 acre-feet. This shows that when a resource such as water grows scarce, the organisms depending on it decline, the cause-and-effect link between resource availability and populations.
Answer: Prepare ahead. Reasonable ideas include storing more water in wet years, expanding conservation, adding reuse or desalination, or agreeing on priority rules before a drought so the cuts are planned rather than fought over. Accept any evidence-based plan.

Differentiation

Support

Give teams a simple worksheet grid that lists the available supply and their demand each year so they can see the shortfall at a glance. Provide sentence starters for negotiating, such as "Our team needs ___ because ___."

Extension

Have teams calculate, each year, the total shortfall between the 8,500 acre-feet of demand and the water available, then propose a written drought plan that assigns priority among the three users and defends it with reasons.

ELL supports

Pre-teach "reservoir," "allocation," and "drought" with a picture of a lake shrinking over four frames. Pair each student with a teammate for the negotiation, and allow the debrief answers to be given orally or with a labeled drawing.