Integrating the NAWQA approach to assessments in rivers and streams By Donna Myers, Bill Wilber, Anne Hoos, and Charlie Crawford U.S. Geological Survey, National Water-Quality Assessment Program Presented to the National Water Quality Monitoring Council Steering Committee October 31, 2006

Occurrence of Pesticides in Water; Streams Shallow Ground Water Streams Major Aquifers Percentage of Samples with Detections Land use Agricultural Urban Undeveloped Mixed (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291)

Common Pesticides in Streams Atrazine Metolachlor Cyanazine Simazine Prometon Tebuthiuron Diazinon Chlorpyrifos Carbaryl UrbanAgricultural Percentage of Samples with Detections (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291)

Potential of Pesticides to Affect Aquatic Life Water Bed Sediment Water Bed Sediment Percentage of Sites Exceeding Benchmarks Agricultural Urban Undeveloped Mixed (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291)

MONTH TOTAL PESTICIDE CONCENTRATION, ug/L PESTICIDE CONCENTRATIONS FOLLOW SEASONAL PATTERNS AGRICULTURAL STREAMS URBAN STREAMS (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291)

Trends in Corn-Belt Herbicides Cyanazine Alachlor Acetochlor Herbicide Use Stream Concentrations (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291)

Change No. 1 – Reporting out at the regional scale

Prediction of Atrazine in Streams (from Pesticides in the Nation’s Streams and Ground Water, , USGS Circular 1291) Change No. 2 – Moving from “monitoring” to “monitoring and modeling”

Three major points 1.Benefits of integrating monitoring with modeling 2.The value that we gained from collaborating with other Federal and State agencies and integrating NAWQA data with data collected by these other programs. 3. The applicability of the regional-scale assessment

South Atlantic Gulf and Tennessee Region

NAWQA: 44 Other USGS: 174 Other agency: 586 (matched to USGS gage) Estimate of nutrient load Change No. 3 – Use of other sources of data outside NAWQA

SPARROW Model Concept

SPARROW Model Framework Monitoring Data 804 Sites Spatial Data Layers Model Predictions 8,092 Stream Reaches

Sources accounting for instream nitrogen load Atmospheric deposition Agricultural land Developed land Point-source discharge of wastewater

Factors controlling nitrogen transport from land to water soil infiltration rate soil organic content water holding capacity in streams and reservoirs stream size (streams with mean flow <1,000 ft 3 /s retention time in reservoirs

NAWQA site with nutrient-load estimate Based on NAWQA sites only + 55% + 30% Based on all sites Prediction Error

Assessment of Total Nitrogen Concentration Mean concentration, in 2002 > 0.7 mg/L 61 % < 0.7 mg/L 39 % Percent of 72,000 stream miles

Sensitive Coastal Areas Yield delivered to estuary from watershed, kg/yr/ha Estuary condition, 1999 Eutrophic, influenced by nitrogen input < 2 2 – 4 4 – 8 > 8

Source Shares Delivered to Sensitive Coastal Areas Atmospheric deposition Agricultural sources Runoff from developed land Point-source discharge Mobile Bay Cape Fear Estuary Savannah River Estuary

1. Improved understanding through integration of monitoring and modeling 2. Integrated data sets 3. Enhanced decision-making Summary