USGS Scientific Investigations Report 2012–5017  - Geomorphic Setting, Aquatic Habitat, and Water-Quality Conditions of the Molalla River, Oregon, 2009

Table 15. Summary of BEST variables and top models explaining patterns in diatom species relative abundance in the Molalla River, Oregon, July and August 2010. 

[Algal taxa relative abundance values for July and August were averaged for this analysis. Abbreviation: D₅₀, median particle size; mm, millimeter] 

Variable	Variable / model correlation and significance
Variable	Rho	P =
Individual variables
Presence of local gravel bars	0.85
Maximum pH in September	0.84
2009 channel sinuosity	0.84
2009 specific bar area	0.71
Averaged active channel width	0.52
D₅₀ particle size (mm)	0.39
Open canopy percent	0.35
Flood plain width (segment)	0.27
Low flow discharge (10 percent exceedance)	0.09
Presence of local streambed bedrock	-0.07
Top combination models
Top 4-Variable Model	0.98	0.007
Presence of local gravel bars
Maximum pH in September
Open canopy percent
Presence of local streambed bedrock
Top 5-Variable Model	0.98	0.012
Presence of local gravel bars
2009 channel sinuosity
D₅₀ particle size (mm)
Open canopy percent
Presence of local streambed bedrock

Geomorphic Setting, Aquatic Habitat, and Water-Quality Conditions of the Molalla River, Oregon, 2009–10

Geomorphic Setting, Aquatic Habitat, and Water-Quality Conditions of the Molalla River, Oregon, 2009–10 