Writing prompt Grade 8 Social Studies & Civics
Halverston's Lake Trembark: Sewer Main or Septic Systems?
A grade 8 argument prompt on whether a lakeside town should charge lakefront owners a sewer assessment or leave them on septic systems, with exemplar and rubric.
Objectives
- Students will write an argument that states a claim, supports it with evidence, and answers a counterclaim.
- Students will explain how a special assessment shifts the cost of a shared water-quality problem among households.
- Students will compare the treatment a municipal plant must achieve with the treatment a septic system provides.
Vocabulary
- Septic system
- A septic system is a small, private wastewater treatment setup buried in the yard of a home that is not connected to city sewers. A tank settles the solids, and the soil in the yard filters the water.
- Effluent
- Effluent is the cleaned water that leaves a treatment plant at the end of the process. It is tested carefully before being released to a river, lake, or the ocean.
- Dissolved oxygen
- Dissolved oxygen is the oxygen gas mixed into water that fish and other underwater animals breathe. Cold, moving water holds more oxygen than warm, still water.
Also: leach field, special assessment, counterclaim
Teacher overview
Local governments regularly decide who pays for a fix when one group of properties causes a problem that the whole community shares. This prompt places students in that decision: the town of Halverston must choose between charging lakefront owners a special assessment to connect to a sewer main and leaving those owners on septic systems under a stricter maintenance rule. A misconception worth addressing before students write is that a septic tank treats sewage the way a treatment plant does. A septic tank mainly settles solids and holds them; the liquid that leaves it is still high in bacteria and nitrogen, and the soil of the leach field does the remaining treatment. Once students understand that the soil is doing the work, the argument about aging systems near a lake becomes concrete rather than abstract.
Prompt
Background: The town of Halverston sits on the north shore of Lake Trembark. About 240 homes ring the lake, and none of them are connected to a sewer line. Each home treats its own wastewater in a septic system.
A septic system has two parts. Solids settle in a buried tank, which has to be pumped out every few years. The liquid that leaves the tank, called effluent, flows into a leach field, where soil filters it before it soaks down to groundwater. Groundwater under the shoreline moves slowly toward the lake. When a system fails, wastewater carrying bacteria and nitrogen reaches the lake with little treatment.
Last summer the county health officer inspected all 240 lakefront systems. Forty-one failed. Most of those were more than 40 years old.
Lake Trembark has grown thick mats of algae for three summers in a row. Nitrogen from lawn fertilizer and from failing septic systems feeds that growth. When the algae die, bacteria use up oxygen as they break the algae down. Most fish need dissolved oxygen above 5 mg/L. Halverston's own lake readings have dropped below that level in late August each of the last three years.
The town board has two plans.
Plan A: build the sewer main. The town would run a sewer line around the lake and send the wastewater to the Halverston reclamation plant. Federal rules require that plant to hold its monthly average BOD and suspended solids to 30 mg/L or less, which is roughly 85 percent removal. BOD measures how much oxygen waste will use up as it breaks down, and raw sewage usually arrives at a plant at 200 to 300 mg/L of BOD. Each lakefront owner would pay a one-time special assessment of $12,000. The town would let owners repay that over 20 years, which works out to about $600 a year, and each home would pay a sewer charge of $46 a month on top of it.
Plan B: keep septic systems and tighten the rules. Every lakefront system would be inspected every three years, at a cost of about $400 to the owner each time. Any system that failed would have to be repaired or replaced within one year. A full replacement in Halverston costs $18,000 to $30,000, and one household pays the whole amount at once.
Two other facts matter to the board. The median household income among the lakefront homes is about $54,000, and those homes already pay about $480 a year for town drinking water. A widely used rule of thumb, built by adding two EPA benchmarks, treats combined water and sewer costs above roughly 4.5 percent of household income as a high burden, though EPA itself has no single official cutoff. Halverston also has older sewer pipes downtown that need repair, and the ASCE 2025 Infrastructure Report Card gave wastewater systems across the country a grade of D+, so the town is not alone in facing repair bills it cannot pay all at once.
Owners are divided. Some say the lake belongs to everyone in Halverston, so everyone should share the cost. Others say they replaced their own systems recently and should not pay $12,000 for a problem they did not create.
Writing task: Should the Halverston town board build the sewer main and charge lakefront owners the special assessment, or should it keep those homes on septic systems under the stricter inspection rule? Write an argument essay. State a clear claim, give at least two reasons supported by evidence from the background above, answer one counterclaim an owner on the other side would raise, and end with a conclusion that follows from your reasons.
Planning Organizer
| Category | Your notes |
|---|---|
| Claim (sewer main with assessment, or septic with stricter inspections?) | |
| Reason 1 and the evidence from the background that supports it | |
| Reason 2 and the evidence from the background that supports it | |
| Counterclaim an owner on the other side would raise | |
| Your rebuttal, and the evidence behind it | |
| Concluding statement that follows from your reasons |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Exemplar & Rubric
Exemplar response:
Halverston should build the sewer main and charge the special assessment, because the lake needs treatment that does not depend on the age of 240 separate systems. A septic system only works while its soil still drains and its tank stays sound, and the health officer found that 41 of the lakefront systems already failed. Most of the failures were in systems more than 40 years old, so the number will keep climbing. The reclamation plant is held to a fixed standard instead. It has to keep its monthly average BOD and suspended solids at 30 mg/L or less, which is about 85 percent removal from sewage that arrives at 200 to 300 mg/L. A single plant that must meet that limit is far more reliable than 240 leach fields that no one sees underground.
The second reason is that the sewer plan protects the lake itself, which is the reason the town is having this argument. Nitrogen from failing systems feeds the algae mats that have covered Lake Trembark for three summers. When those mats die, bacteria strip oxygen out of the water, and Halverston's readings have fallen below the 5 mg/L that most fish need every August for three years running. Stopping a steady source of nitrogen is the one action the board can take that reaches the cause instead of the symptom.
Owners who recently replaced their own systems will argue that they should not pay $12,000 for failures on other people's property. That objection is reasonable, and the board should answer it directly rather than dismiss it. Still, the assessment buys those owners something real. A new septic system will also age, and its owner faces an $18,000 to $30,000 replacement bill alone, which is one third to more than half of a $54,000 household income in a single year. The assessment spreads a smaller cost across 20 years instead. At about $600 a year plus $46 a month, the sewer adds roughly $1,152 to a household's yearly cost. Added to the $480 those homes already pay for drinking water, the total is close to $1,632, or about 3 percent of a $54,000 income, which stays under the 4.5 percent rule of thumb for a high burden. The board could also credit owners who replaced a system in the last few years, which would answer the fairness objection without giving up the sewer.
The board should approve the sewer main and the assessment. The plan replaces aging systems that are already failing with treatment held to a federal limit, it cuts the nitrogen that is driving the algae and the oxygen crashes, and it turns an unpredictable replacement bill into a payment most lakefront households can carry. Waiting only moves the cost to the next set of owners whose systems fail.
Rubric:
| Criterion | Emerging | Developing | Proficient | Advanced |
|---|---|---|---|---|
| Claim | States no clear position on the two plans | Names a plan but the position shifts or stays vague | States one clear position and holds it through the essay | States a clear position and previews the reasons that will support it |
| Evidence and reasoning | Uses no evidence from the background | Repeats one figure or detail without explaining what it shows | Uses at least two specific details from the background and explains how each supports the claim | Uses several specific details, including at least one cost figure and one water-quality figure, and explains how each strengthens the argument |
| Counterclaim and rebuttal | Names no opposing view | Mentions an opposing view but offers no rebuttal | States a counterclaim an owner would actually raise and answers it | States the counterclaim fairly, answers it with specific evidence, and connects the rebuttal back to the claim |
| Organization and conventions | Ideas are disconnected and errors block meaning | Some paragraph structure; errors are noticeable but meaning survives | Clear paragraphs with transitions; few errors | Purposeful structure with a conclusion that follows from the reasons; nearly error-free |
Differentiation
Support
Give students a completed first row of the organizer for the town of Halverston so they can see the level of detail expected, and provide sentence starters for the rest, such as "One reason Halverston should ___ is ___, because the background states ___." Allow the counterclaim and rebuttal to be written as two linked sentences rather than a full paragraph, and let students choose two figures from the background rather than searching all of them.
Extension
Ask students to write a second rebuttal that answers this objection from a downtown resident of the town of Halverston: the board should spend the money on the aging downtown sewer pipes instead of a new main around the lake. A strong answer will use the assessment structure, since lakefront owners rather than the general fund would carry the $12,000, and will acknowledge that the downtown pipes still need a plan.
ELL supports
Pre-teach septic system, leach field, special assessment, effluent, and counterclaim with a labeled cross-section drawing of a tank and leach field beside a drawing of a sewer main running to a plant. Provide a two-column chart with Plan A and Plan B headings so students can sort the background details before drafting. Allow the organizer to be completed in short phrases, and supply a word bank of argument connectives such as "because," "however," "instead," and "as a result."
Extensions
Have students rewrite their essay as a two-minute public comment for a town of Halverston board meeting, keeping the claim and the strongest reason while cutting everything that will not survive a spoken time limit. Students can then compare which evidence held up in the shorter form. A second option is to have small groups draft the actual motion the board would vote on, including whether owners who replaced a system within the last five years receive a credit against the assessment, and then explain in writing why they set that cutoff where they did.