Stream Ecology Notes
Animal
Total
Rating
Points
Rating Scale
Mayfly
28
10
280
1000
Excellent
Cranefly
5
6
30
900
Very Good
Stonefly
11
10
110
800
Good
Caddisfly
20
8
160
700
Slight pollution
Crawfish
7
6
42
600
Mild pollution
Midge larvae
10
3
30
500
Moderate pollution
Leeches
3
1
3
400
Significant pollution
Bloodworms
5
0
0
300
Do not swim
Gilled snail
4
5
20
200 or less
Sewage quality
Clams
7
3
21

TOTALS
100

696

Your class is collecting macroinvertebrates (insects & other small animals found in water) to determine the pollution level in a local creek. Each macroinvertebrate that you collect has a 'Pollution Rating' between 0 and 10. A rating of 0 means the animal is usually found in very polluted water. A rating of 10 means it is only found in very clean water. A total of 100 insects are caught, and the total number of points is added up.

Based on the stream ecology class notebook, what conclusion can you draw about the creek?

A)
You should not swim in this creek again, as it is highly polluted.

B)
Your community should be commended, as the water quality is excellent.

C)
The insect population indicates the presence of no pollutatnts at all.

D)
The creek could probably benefit from a clean-up, but it is still safe to