Hirschman, D, Seipp, B, and Schueler, T. 2017.Performance Enhancing Devices for Stormwater Best Management Practices. Prepared by Hirschman Water & Environment, LLC, Center for Watershed Protection, and Chesapeake Network. 38 pages   This report focuses on the capability of performance enhancing devices (PEDs) to increase nitrogen and phosphorus removal in bioretention, sand filters and other low impact development (LID) practices. Common PED strategies include adding media amendments, incorporating an internal water storage (IWS) zone in the underdrain system and maximizing plant uptake. This report summarizes the findings of an extensive literature review and recommends options for potentially crediting PEDs by adapting existing Chesapeake Bay nutrient reduction protocols. This document aims to provide technical support for Chesapeake Bay managers and stormwater professionals to decide whether nutrient removal credits should be offered for bioretention, sand filter, and other LID practices that rely on one or more performance enhancing devices (PEDs).