National Water Quality Program
Regional Stream Quality Assessments
Midwest Stream Quality Assessment: Linking the
landscape, in-stream stressors, and ecology
Major Findings of MSQAExtensive modification of the landscape in the Midwestern United States has profoundly
affected the condition of streams. Row crops and pavement have replaced grasslands and
woodlands, streams have been straightened, and wetlands and fields have been drained.
These actions alter the stream habitat and add nutrients and pesticides to small streams.
The physical alterations and chemicals present are “stressors” that are adversely affecting
the fish, invertebrates, and algae living in small Midwestern streams.
Michael Peirce, Creative Commons 2.0
3
MSQA by the
numbers …• 6 nutrients
• 11 states
• 12 weeks
• 100 streams
• 135 fish species
• 227 pesticides
• 1200 water samples
• 100+ USGS personnel
Fish
• Fish species loss is most related to increases in streambed sedimentation
• Fish also are affected by nitrogen, phosphorus, low dissolved oxygen, and degraded riparian (near-stream) habitat
More sedimentation leads
to a loss of “sensitive” fish
species
Meador and Frey, 2018, JAWRA
Green sunfish
Invertebrates
Mayfly
Zleng, Creative Commons 2.0
Waite and Van Metre, 2017, Freshwater Science
A biologist uses a fine-mesh net
to collect invertebrates from a
stream riffle
• Riparian condition, sediment grainsize, velocity, channel shape, ammonia, and insecticides affect invertebrates
• Mayflies are particularly sensitive to bifenthrin, a pyrethroid insecticide
Algae
Munn et al., 2018, Ecological Indicators
• Habitat, phosphorus, and herbicides are stressors to algal communities
• Streambed sediment size affects algal sensitivity to other stressors: o Algae in streams with fine sediment are affected by water
temperature and herbicideso Algae in streams with coarse sediment are affected by water
temperature and depth
In streams, algae
often grow on rocks.
Algae are sampled
by scraping the rock
surface with a stiff
brush.
“Stream straightening” changes stream habitat by removing riparian woodlands, increasing water velocity and erosion, and decreasing interaction between the stream water and the streambed.
Straightening and loss of healthy riparian habitat are evident in this Google Earth image
from NE Iowa. Streams are visible as light green lines over which a grid of rural roads is
superimposed.
Peter Van Metre
http://webapps.usgs.gov/RSQA/
http://water.usgs.gov/nawqa/
https://www.sciencebase.gov/catalog/