On October 1 and November 19, the 7th grade
students of Jr. CAM conducted water quality tests on the
East Fork of the Lewis River, just north of Battle
Ground, WA. The students, lead by trained volunteers
recruited by Christine Sullivan of the Environmental
Information Cooperative, conducted a number of physical,
chemical, and biological tests. The biological assessment
was made based upon the Pollution Tolerance Index (PTI).
Using an average score from our two classes of students on November 19,
the PTI rating for the East Fork of the Lewis River at
Lewisville Park was "Good" -- close to, but not quite
"Excellent." The cumulative scores for each class were
"20" and "19." A score of "23" or above is needed for an
"Excellent" rating. Results of our physical and chemical
tests have been recorded to the state-wide NatureMapping
- Water Module database.
Using data from the students' on-site assessments, the
number of macroinvertebrate types found on November 19,
2004, included the following:
- 1 type of caddisfly larva (not counting filtering
caddisfly)
- 4 types of mayfly
- 1 riffle beetle (adult)
- 3 types of stoneflies
- 2 types of beetle larva
- 1 type of filtering caddisfly
- 1 scud
- 1 sowbug
- 1 type of water mite
- 1 type of aquatic earthworm
- 1 type of blackfly larva
- 1 type of midge larva
- 1 spotted water beetle (adult)
Due to our counting method, in which the samples were
seperated and evaluated by smaller groups of students,
this accounting of the macroinvertebrates would be
minimums. We could only count, with certainty, the
largest number of different macroinvertebrate types found
for any one group of students.
The following pages record some of the
macroinvertebrates we encountered during our study of the
East Fork at Lewisville Park this Fall (October - November). In some cases, the number of
macro types photographed will exceed the number shown in
the list above. For example, we have photos of at least
seven genera of mayflies found at Lewisville during this
fall, while the list above only recorded four types of
mayfly found on November 19.
A larger image of the macros can be accessed by
clicking on the thumbnail pictures. These links will also
reveal some additional information about the organisms
size and date of capture. For other images of macros
recorded prior to this fall and from other locations, go
to the Jr. CAM Catalog
of Aquatic Macroinvertebrates . We hope you enjoy the
pictures.
