Progress in Estimating Loads at Mallard Island Nicole David Lester McKee Item #4

Objective Obtain contaminant data collected at Mallard Island Use concentrations in combination with sediment data to estimate loads Calculate long-term averages beginning with WY 1995 Make recommendations to improve TMDLs Item #4

Methods 1.Use SSC data from USGS from 1995 to present 2.Use instantaneous SSC and contaminant data to develop a regression relationship (WY ) 3.Estimate 15 minute contaminant concentrations 4.Calculate daily average concentrations 5.Use linear interpolation to fill data gaps 6.Combine estimated daily concentrations with Delta Outflow to estimate daily advective loads 7.Correct loads for the effect of tidal influence and dispersion Item #4

Step by Step SSC Turbidity measurements taken at MI in 15 minute intervals with optical sensor (USGS) Data processing system utilized to erase unusual high voltage outputs of short duration Data converted to SSC concentrations using linear regression equation and calibrated with instantaneous samples Item #4

SSC data for the Period of Record Item #4

Step by Step DAYFLOW Discharge calculated continuously by DWR Input data for discharge include the principal Delta stream inflows, Delta precipitation, Delta exports, and Delta gross channel depletions DAYFLOW (computer program for determining Delta hydrology) accounts for advective flux only Item #4

Dayflow for the Study Period Item #4

Step by Step Load Analysis Scatter plot for contaminant and SSC relationship including all data collected Item #4

Step by Step Load Analysis 15 minute contaminant concentrations estimated using regression line DAYFLOW combined with daily SSC to estimate daily advective loads Tidally driven advective and dispersive fluxes estimated with velocity and SSC data (USGS) Freshwater advective loads adjusted with estimates for tidally driven fluxes Errors associated with calculation and an additional error for lab analysis are estimated Item #4

Step by Step Load Analysis =0.11*SSC+2.98 Dayflow*3600*24*1000*HgT dayAv/1,000,000,000,000 Dispersive=-Advective*Dispersive Flux Ratio Advective+Dispersive=Total Item #4

Samples Collected * Preliminary data Item #4

SSC – Hg Relationship y = 0.11x R 2 =0.74 y = 0.22x R 2 =0.66

Low Flow Data Item #4

Results Revised annual mercury load for Delta Particles leaving Delta during high flows are more contaminated New load estimates for mercury about 33% higher than previously predicted Item #4

Flows and Mercury

Loads from the Delta * Preliminary data, still missing September DO NOT QUOTE! Item #4

Unique contaminant dataset from Delta gained through January 2006 flood Item #4

Delta Outflow from 12/20/05 to 01/25/06 370,000 cfs Item #4

THANK YOU Item #4