Multi-scale landscape factors influencing stream water quality in the state of Oregon
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Authors: M. S. Nash, D. T. Heggem, D. Ebert, T. G. Wade, and R. K. Hall
Date: 2009
Journal: Environmental Monitoring and Assessment
Volume: 156
Number: 1-4
Pages: 343-360
Summary of Methods: Surface water quality data were collected from 1990-1994 across the state of Oregon, including eastern arid lands with high desert prairie. Data were analyzed according to landscape metrics and a grazing potential index (GPI) based on proximity to water, land ownership and forage availability, to determine distribution and relationship of biotic (enterococci bacteria) and abiotic (nitrogen-N and phosphorus-P) for indication of animal presence and influence on water quality. Metrics included percentage forest, riparian, agriculture, manmade or natural barren, natural grassland, shrubland, wetland and urban land areas at 485 sample sites on upland watershed area. Slope and landform were also included in GPI calculations.
Article Summary / Main Points: Forage related variables included in the GPI contributed to increasing or decreasing nutrient concentrations in surface water, making them valuable for future grazing analyses. Enterococci concentrations were elevated more in anthropogenic-affected areas, than in agricultural, and specifically to areas within proximity of sample sites, rather than at watershed scale. While N and P concentrations were affected at multiple landscape scales, the authors conclude that N from animal wastes and other sources can be more concentrated in streams within close proximity than those farther away from the source. The authors prescribe both structural and non-structural systems to be evaluated for potential to reduce fecal contamination to surface waters (e.g. fencing near streams to exclude cattle).
Vegetation Types: All Vegetation Types
MLRA Ecoregions: Not Applicable
Agrovoc Control Words: Grazing Water Quality Watershed
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: grazing management, landscape metrics, grazing potential index (gpi), surface water quality, nutrients, enterococci, waste management
Annotation: This paper covers water quality across the state of Oregon, but gives a good picture of other factors, along with grazing too near streams, involved in surface water pollution.
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