Natural Phosphorus Sources for the Pacific Northwest

Phosphorus is a naturally occurring element found in all rocks; the amount varies by the
type of rock. The amount of phosphorus in sediments is expected to be correlated with
the amount of phosphorus in the parent rocks. Streambed sediment collected by the
National Uranium Resource Evaluation (NURE) Program were used to estimate the
variation of phosphorus across the Pacific Northwest. This file provides an estimate
of the mean concentration of phosphorus in soils for each incremental catchment of
the USGS Pacific Northwest SPARROW model.