| Date |
Site |
River
kilometer |
Chlorophyll-a
(mg/m2) |
Qualitative description of
benthic periphyton |
Qualitative description of
benthic invertebrates |
| July 30, 2010 |
Molalla River upstream of
Glen Avon Bridge |
42.8 |
55 |
Moderately thick diatom biolfilm with some tufts
of filamentous green algae. |
Numerous caddisflies (Dicosmoecus and
Glossosomidae), mayflies (Heptageniidae), and
stoneflies (Calaneria), and numerous midges
(Chironomidae). |
| July 30, 2010 |
Molalla River upstream of
Highway 211 Bridge |
30.1 |
30 |
Thick diatom biolfilm. |
Numerous caddisflies (Dicosmoecus and
Glossosomidae), mayflies (Heptageniidae),
and stoneflies (Calaneria), and numerous
midges (Chironomidae). |
| July 30, 2010 |
Molalla River upstream of
Highway 213 Bridge |
23.5 |
39 |
Moderately thick diatom biofilms and filamentous
blue green mats (Oscillatoria sp.) starting to flake off. |
Numerous caddisflies (Dicosmoecus and
Glossosomidae), mayflies (Heptageniidae), and
stoneflies (Calaneria), and numerous midges
(Chironomidae). |
| July 30, 2010 |
Molalla River upstream of
Goods Bridge |
9.7 |
38 |
Moderately thick diatom biolfilm. |
Snails and midges (Chironomidae)
abundant, with fewer mayflies (Heptageneiidae),
stoneflies (Calaneria), caddisflies (Glossosomidae). |
| July 30, 2010 |
Molalla River downstream from
Knights Bridge |
4.3 |
42 |
Large growths of Cladophora glomerata. |
Snails and midges (Chironomidae)
abundant, with fewer caddisflies (Glossosomidae)
and stoneflies. |
| Aug. 15, 2010 |
Molalla River upstream of
Glen Avon Bridge |
42.8 |
41 |
Thin diatom biofilm with filamentous blue-green
algae, clumps of stalked diatoms, and lesser
filamentous green algae. |
Fewer benthic invertebrates; a few stoneflies and
caddisflies (pupating). |
| Aug. 15, 2010 |
Molalla River upstream of
Highway 211 Bridge |
30.1 |
38 |
Moderately thick diatom biofilm with lesser
filamentous blue-green and filamentous
green algae. |
Fewer benthic invertebrates; a few stoneflies,
mayflies (Heptageniidae), and caddisflies (pupating). |
| Aug. 15, 2010 |
Molalla River upstream of
Highway 213 Bridge |
23.5 |
40 |
Moderately thick diatom biofilm with lesser
filamentous blue-green and filamentous
green algae. |
Fewer benthic invertebrates; a few stoneflies, mayflies
(Heptageniidae), and pupating
caddisflies
(Glossosomid and Dicosmoecus). |
| Aug. 15, 2010 |
Molalla River upstream of
Goods Bridge |
9.7 |
63 |
Moderately thick diatom biofilm with clumps
of stalked diatoms; extensive growth of
filamentous green algae along right bank
upstream of the bridge. |
Snails abundant with a few stoneflies and
caddisflies (Glossosomidae). |
| Aug. 15, 2010 |
Molalla River downstream from
Knights Bridge |
4.3 |
113 |
Moderately thick diatom biofilm with some
decaying filamentous green algae. |
Snails abundant. |
U.S. Department of the Interior |
U.S. Geological Survey