Evaluating External Nutrient and Suspended-Sediment Loads to Upper Klamath Lake, Oregon, Using Surrogate Regressions with Real-Time Turbidity and Acoustic Backscatter Data
Title: Evaluating External Nutrient and Suspended-Sediment Loads to Upper Klamath Lake, Oregon, Using Surrogate Regressions with Real-Time Turbidity and Acoustic Backscatter Data
Category: Technical Report
File: Schenk_et_al_2016_0450_Evaluating-external-nutrient.pdf
Updated Date: 08.03.2018
Author(s)/Source(s): Liam N. Schenk, Chauncey W. Anderson, Paul Diaz, Marc A. Stewart
Publication Date: 2016
Focal Topic: Contaminants, Water Quality, Sediment & Geomorphology
Location: Upper Klamath
Watershed Code: 180102
Suspended-sediment and total phosphorus loads were computed for two sites in the Upper Klamath Basin on the Wood and Williamson Rivers, the two main tributaries to Upper Klamath Lake. High temporal resolution turbidity and acoustic backscatter data were used to develop surrogate regression models to compute instantaneous concentrations and loads on these rivers. Regression models for the Williamson River site showed strong correlations of turbidity with total phosphorus and suspended-sediment concentrations (adjusted coefficients of determination [Adj R2]=0.73 and 0.95, respectively). Regression models for the Wood River site had relatively poor, although statistically significant, relations of turbidity with total phosphorus, and turbidity and acoustic backscatter with suspended sediment concentration, with high prediction uncertainty. Total phosphorus loads for the partial 2014 water year (excluding October and November 2013) were 39 and 28 metric tons for the Williamson and Wood Rivers, respectively. These values are within the low range of phosphorus loads computed for these rivers from prior studies using water-quality data collected by the Klamath Tribes. The 2014 partial year total phosphorus loads on the Williamson and Wood Rivers are assumed to be biased low because of the absence of data from the first 2 months of water year 2014, and the drought conditions that were prevalent during that water year. Therefore, total phosphorus and suspended-sediment loads in this report should be considered as representative of a low-water year for the two study sites. Comparing loads from the Williamson and Wood River monitoring sites for November 2013–September 2014 shows that the Williamson and Sprague Rivers combined, as measured at the Williamson River site, contributed substantially more suspended sediment to Upper Klamath Lake than the Wood River, with 4,360 and 1,450 metric tons measured, respectively.
Keyword Tags:Turbidity, Suspended-Sediment Load, Nutrient