Urban vs. Rural Rapid Stream Assessment – Comparing Johnson Creek & Eagle Creek Reaches in the PNW

Abstract:
The EPA’s Rapid Stream Assessment protocols were used to survey two streams just outside Portland, Oregon. Johnson Creek has a far more urbanized land use as much of it lies within Portland’s urban growth boundary while Eagle Creek’s watershed doesn’t include the same kind of development levels that Johnson Creek does. Therefore, using these two watersheds & streams we tried to assess whether the level of urbanization within each watershed had a significant impact on stream health. Using assessment of physical characteristics, water quality (conductivity, %EPT % turbidity), and survey techniques to map depth/flow we were able to discern a significant (Wilcox nonparametric t-test, p<0.05) difference between each streams’ means & compare the land use patterns to fill in the contextual shift of inputs between 2001-2011. It was found that Johnson Creek has the markers of ‘urban stream syndrome’ described by Burton et al in 2009 – a useful comparison for Eagle Creek which may see increased low impact development and shifts in vegetative structures. In turn, those vegetative community shifts are likely to impact the physical and habitat characteristics of the stream along with the water quality. Moving forward it’s highly important to mitigate fragmentation, dredging & impervious surfaces along with invasive species as our cities grow.

Key Skills Used:
- Watershed Delineation
- USGS National Land Cover Datasets
- ESRI’s ArcMap 10.3/10.4 GIS
- R.Studio
- EPA Rapid Bioassessment Protocol
- Macroinvertebrate EPT Index
- Water Quality Parameters