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Reading passage Grade 7 Health & Consumer Science

Reading a Health Advisory: An Algal Bloom at Pinehollow Lake

A grade 7 informational passage on a fictional lake's algal bloom advisory, teaching students to read a water health advisory as a practical consumer and safety skill.

Objectives

  1. Students will identify the cause of an algal bloom described in an informational passage.
  2. Students will distinguish a swim advisory from a boil-water advisory.
  3. Students will explain, using passage details, why a lake advisory can affect some activities and not others.

Vocabulary

Algal bloom
An algal bloom is a fast, thick growth of algae that can turn a lake green and scummy. Blooms happen when the water gets lots of nutrients and warm sunshine, and some blooms make toxins.
Nonpoint source pollution
Nonpoint source pollution is pollution that washes off the land a little at a time from many places, like lawns, streets, and farms, instead of coming out of one pipe. It is the hardest kind of water pollution to control.
Health advisory
A warning from EPA about how much of a chemical people can safely drink over a lifetime. It guides utilities before an official legal limit exists.

Teacher overview

Reading a posted health advisory correctly is a practical safety skill as well as an environmental science topic, and this original passage follows a fictional county water quality technician as she investigates and responds to an algal bloom at a fictional lake. The passage explains where the nutrients feeding the bloom came from, what a swim advisory actually tells visitors to do, and why that advisory is not the same thing as a boil-water advisory affecting a town's tap water. The comprehension questions mix direct retrieval with inference, matching how RI.7.1 is assessed at this grade.

Reading a Health Advisory: An Algal Bloom at Pinehollow Lake — Grade 7 Health & Consumer Science
Name: ____________________________ Date: ______________

Passage

The Advisory at Pinehollow Lake

Dana Reyes had checked the water at Pinehollow Lake every week all summer without finding anything unusual. In late July, that changed. A wide patch near the swimming beach had turned a thick, blue-green color overnight, and a faint smell drifted off the water that had not been there the week before.

Dana works as a water quality technician for the county, and part of her job is investigating exactly this kind of sudden change. She collected a sample from the discolored patch and looked at it under a microscope back at her lab. The water was full of algae, tiny plant-like organisms that live in almost every lake in small numbers. The problem at Pinehollow Lake was not that algae existed. The problem was how much of it had suddenly appeared, a change called an algal bloom.

Algae need the same basic things plants do to grow. They need sunlight, warm water, and nutrients like nitrogen and phosphorus. Pinehollow Lake already had plenty of sun and warmth, since the bloom appeared during a stretch of unusually hot, sunny weeks. What had changed was the nutrient supply. Dana traced the extra nutrients to nonpoint source pollution. This term describes pollution that does not come from one single pipe or outlet. Instead, it washes in slowly from many small sources across the watershed. In this case, fertilizer from lawns near the shoreline was the source. Rain carried it into storm drains and then into the lake. This gave the algae exactly what they needed to multiply quickly once the hot weather arrived.

A fast-growing bloom creates a second problem beyond the discoloration itself. As huge numbers of algae eventually die, bacteria in the water break down their remains. That process uses up dissolved oxygen. Most fish need water with more than about 5 mg/L of dissolved oxygen to stay healthy. A large bloom's die-off can pull oxygen levels below that point. This is one reason a bad bloom can sometimes be followed by dead fish washing up along a shoreline.

Some algal blooms can produce substances that irritate skin or cause illness if swallowed. Because of this, Dana's next step was posting a health advisory at the swimming beach. She also notified the county health department. The sign warned visitors not to swim in or wade through the discolored water. It also told them to keep pets from drinking from it. The sign did not warn people away from boating or fishing farther out on the lake, where the water looked clear. Dana explained to a reporter that this advisory was entirely different from a boil-water advisory. A boil-water advisory applies to a town's piped drinking water supply. It tells people to boil tap water before drinking it. Pinehollow Lake's advisory concerned only contact with the lake itself, not any town's tap water, since the two systems are not connected.

Within two weeks, cooler weather and a period of steady wind mixed the lake. The bloom began to fade, and Dana lifted the advisory after a follow-up sample came back clear. She reminded lakefront homeowners that keeping fertilizer and yard waste away from the shoreline the following spring would make another bloom less likely.

Questions

  1. What change did Dana Reyes first notice at Pinehollow Lake in late July?
  2. According to the passage, what two ingredients, beyond the nutrients Dana traced, do algae need to grow quickly?
  3. Why do you think the bloom appeared specifically during a stretch of hot, sunny weeks rather than earlier in the summer? Use passage details to support your answer.
  4. According to the passage, what happens to dissolved oxygen levels when large numbers of algae die and decompose, and why does that matter for fish?
  5. Based on the passage, why did the health advisory apply only to the swimming beach and not to boating or fishing farther out on the lake?
  6. Using details from the passage, explain two things a family visiting Pinehollow Lake should do differently once they see the advisory sign posted.
  7. What is the difference between the advisory posted at Pinehollow Lake and a boil-water advisory, according to the passage?
  8. What does the passage mean by "nonpoint source pollution," and where does it say the extra nutrients at Pinehollow Lake came from?

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: She noticed that a wide patch of water near the swimming beach had turned a thick, blue-green color overnight, along with a faint smell that had not been there the week before.
  2. Answer: Sunlight and warm water. The passage states that algae need sunlight, warm water, and nutrients to grow, and that Pinehollow Lake already had plenty of sun and warmth before the bloom appeared.
  3. Answer: Answers will vary but should note that the lake already had the sunlight and warmth algae need throughout the summer, so once the extra nutrients from fertilizer runoff arrived, the hot, sunny weeks gave the algae everything needed to multiply quickly all at once.
  4. Answer: Bacteria that break down the dead algae use up dissolved oxygen in the water, which can push oxygen levels below the roughly 5 mg/L most fish need, sometimes leading to dead fish along the shoreline.
  5. Answer: The advisory concerned direct skin contact with the discolored water near the beach, where the bloom was concentrated, while the water farther out on the lake looked clear and was not affected in the same way.
  6. Answer: Accept any two of: avoid swimming or wading in the discolored water, keep pets from drinking from the affected area, and understand that boating or fishing farther from the beach was not restricted by the advisory.
  7. Answer: The Pinehollow Lake advisory warned people not to make contact with the discolored lake water itself, while a boil-water advisory applies to a town's piped tap water and tells people to boil that water before drinking it; the passage states the two systems are not connected.
  8. Answer: Nonpoint source pollution is pollution that does not come from one identifiable pipe or outlet but washes in gradually from many small sources across a watershed. The passage says the extra nutrients came from fertilizer on lawns near the shoreline, carried by rain into storm drains and then into the lake.

Differentiation

Support (below grade level)

Provide a simple cause-and-effect chart (Fertilizer on lawns → Rain washes it into storm drains → Nutrients reach lake → Algae grow quickly) for students to reference while answering, and allow question 3 to be answered as a short spoken response instead of writing.

Extension (above grade level)

Ask students to research, using only the passage and teacher-provided facts rather than outside sources, what steps a homeowner near a lake could take to reduce fertilizer runoff, and write a short paragraph explaining how those steps connect to what happened in the passage.

ELL supports

Pre-teach algal bloom, nonpoint source pollution, and health advisory with simple images (a lake turning green, rain washing fertilizer off a lawn, a warning sign at a beach) before reading. Allow literal questions (1, 2, 4, 7) to be answered with short phrases rather than full sentences.