A hands-on, collaborative Grade 4-5 science lesson where students investigate how rainfall, land use, and runoff impact Lake Erie's freshwater ecosystem using collaborative mapping and water quality bio-indicators.
Place a pinch of cocoa (eroded soil) and green powder (fertilizer) on the farm slopes.
04
Make it Rain!
Use the spray bottle to create a rainstorm over the high ridges. Watch where everything flows!
Observation Goal: Did the "fertilizer" stay where it was placed, or did gravity carry it down?
CLUE 2
Source Investigation: Where Does It Come From?
Two Types of Runoff
Easy to Pinpoint
Point Source Pollution
Pollution coming out of a single, identifiable tube, ditch, or pipe (such as a factory or sewage pipe).
🔎 Status: Heavily regulated and monitored by environmental laws since 1972!
The Harder Mystery
Non-Point Source Runoff
Runoff washing across millions of acres of farm fields, suburban lawns, parking lots, and streets simultaneously.
🚨 Detective Finding: This is the #1 cause of Lake Erie's summer algae!
Key Nutrients: Phosphorus from fertilizer and livestock manure supercharges algae growth. 1 lb Phosphorus = 500 lbs Algae
CLUE 3
Bio-Detectives: Living Water Indicators
Macroinvertebrates Tell the Truth
GROUP 1
Pollution Sensitive
Cannot survive dirty water or low oxygen.
• Mayfly Nymph
• Caddisfly Larva
Sign of: Healthy, clean streams
GROUP 2
Somewhat Tolerant
Can tolerate moderate sediment & nutrients.
• Crayfish
• Dragonfly Nymph
Sign of: Fair water quality
GROUP 3
Pollution Tolerant
Survives in low oxygen and high mud.
• Tubifex Bloodworms
• Aquatic Leeches
Sign of: Degraded water conditions
Turbidity Check: We also use black-and-white Secchi disks to test water clarity. Station Audit Tool
CASE CLOSED
How Can We Protect Lake Erie?
Action Plan
1. Restore Wetlands
Wetlands act as "nature's kidneys," trapping excess sediment and absorbing nitrogen before it reaches the lake.
2. Buffer Strips
Farmers plant deep-rooted native grasses along stream edges to soak up fertilizers before they wash into tributaries.
3. City Rain Gardens
Urban neighborhoods install rain barrels, permeable pavement, and plant gardens to let rainwater soak into the ground.
"Every neighborhood is in a watershed. What we do on the land matters for all of us!"
In the mid-1800s, pioneers settled the region. They chopped down the forest and installed millions of clay drainage pipes called "drain tiles" buried beneath the soil. The drained swamp revealed some of the richest agricultural soil on Earth! But draining the swamp came with a hidden cost: without wetlands to slow down and filter rainwater, runoff now shoots through farm drain tiles into ditches and rivers in a matter of hours.
3 Living Water Clues: The River Bottom Detectives
How do water detectives prove where water is healthy and where it is suffering? They look under river rocks for benthic macroinvertebrates—small animals without backbones that live at the bottom of streams. Because these creatures cannot swim away from pollution, they tell the story of the river over time:
Group 1: Clean Water Heroes
Mayflies, stoneflies, and caddisflies need lots of dissolved oxygen and clear gravel beds. Finding them means water is pure!
Group 2: Middle Defenders
Crayfish, dragonfly nymphs, and clams tolerate some warmth and cloudy mud, but still need decent water quality.
Group 3: Tough Survivors
Tubifex worms, leeches, and midge larvae survive in warm, murky water with almost no oxygen. High numbers signal distress!
Field Sleuth Checkpoints (Complete During Reading)
1. Why did the Great Black Swamp prevent algal blooms before it was drained in the 1800s?
2. If an investigator finds dozens of tubifex worms and zero caddisflies, what does that indicate about the stream?
Lake Erie Watershed Detectives • Reading Passage Page 2 of 2
3. Shade the Western Basin where algae blooms concentrate due to shallow depth.
MAUMEE BASIN TO LAKE ERIE CORRIDOR
N
A
Station A: St. Marys Forest Headwaters (Elev: 860 ft)
Station D: Western Lake Erie Basin (Average Depth: 24 ft)
Shallowest, warmest Great Lake water; prime condition for cyanobacteria blooms.
Algal Bloom Epicenter
Team Spatial Analysis Questions
1. How does elevation change from Station A to Station D? Why does this matter for runoff?
2. Why does Station D suffer worse algae problems than deeper parts of Lake Erie?
Lake Erie Watershed Detectives • Activity Guide Page 2 of 2
3. Look at Station D in Lake Erie. Why does dissolved oxygen drop dangerously low when massive algal blooms die and decompose?
Lake Erie Watershed Detectives • Student Worksheet Page 1 of 2
Case Synthesis & Environmental Action Plan
Investigation Final Report
4. Multiple Choice Check: Why is agricultural runoff in the Maumee watershed classified as "non-point source pollution"?
A It enters the lake from a single broken industrial sewage pipe.
B It washes off thousands of individual farm fields across a vast land area whenever it rains.
C It only happens underground and never touches river water or sunlight.
D It is produced exclusively by ships sailing across Lake Erie's central shipping channels.
5. Final Case Defense: Claim • Evidence • Reasoning (CER) Summative Response
Prompt: Write a scientific argument explaining what causes Lake Erie's summer algal blooms and how watershed land use connects to the health of the lake.
CLAIM (A direct statement answering what causes the blooms):
EVIDENCE (Provide specific data from Station A, B, C, or D and your simulation):
REASONING (Explain the science: how does runoff travel downhill and feed algae?):
6. Detective Action Recommendation: Check 2 best practices to heal Lake Erie:
Plant wetland buffer strips along farm ditches to filter runoff
Pave over all remaining wetlands with concrete highways
Plant off-season cover crops to keep loose topsoil anchored
Spray lawn fertilizer right before heavy thunderstorms
Lake Erie Watershed Detectives • Student Worksheet Page 2 of 2
