AEI) is performing water quality monitoring and data analysis services to refine Event Mean Concentrations (EMCs) used by Pinellas County across various programs such as the National Pollution Discharge Elimination (NPDES), Municipal Separate Storm Sewer (MS4) permit reporting, various pollutant loading estimations, and Best Management Practices (BMP) pollution reduction estimates. The EMCs that the County currently reports in their Year 3 NPDES report are from a variety of studies, some dating back to 1990. The County wishes to begin reviewing and revising EMCs based on new local stormwater monitoring and has requested AEI assist in conducting the monitoring and analyses required to update EMCs for some of the most common County land uses. AEI is developing a Sampling and Analysis Plan (SAP) which will implement the deployment of autosamplers to collect baseflow (background) and storm event water quality and flow data for a one-year period. The collected data will be analyzed to determine the appropriate and localized EMC values to be used by the County.