Monitoring and Evaluating Nonpoint Source Watershed Projects

FOREWARD

The diffuse nature of nonpoint sources and the variety of pollutants generated by them create a challenge for their effective control requiring a systematic approach based on assessment, planning, implementation, and evaluation. Monitoring is an important component in all four of these activities. While substantial progress has been made since 1972 in the protection and enhancement of water quality, much work is still needed to identify nonpoint source management strategies that are both effective and economically achievable under a wide range of conditions. Lack of adequate information on best management approaches is the major obstacle in developing effective watershed management strategies. We are relearning previous lessons because we have failed to institutionalize previous lessons learned from intensive monitoring efforts from 1970 to the present. This version of the nonpoint source monitoring guide (guide) incorporates the monitoring lessons learned from the Rural Clean Water Program (RCWP), the Clean Water Act Section 319 National Nonpoint Source Monitoring Program (NNPSMP), and other efforts to provide a state-of-the-reference for monitoring nonpoint source projects. Monitoring plays an important role in addressing the need to evaluate our watershed management efforts and document the lessons learned so we can use them as a foundation for future management efforts. This guide is written primarily for those who develop and implement monitoring plans for watershed management projects, but it can also be used by those who wish to evaluate the technical merits of monitoring proposals they might sponsor. It is an update to the 1997 Monitoring Guidance for Determining the Effectiveness of Nonpoint Source Controls (EPA 841-B-96-004) and includes many references to that document. The style and technical level of this guidance are intended to make it accessible to both beginners and experts alike. Numerous real-world examples from RCWP and NNPSMP projects are provided to give the reader a true sense of the challenges faced by those who have monitored waters impacted by nonpoint sources. Included in the guidance document are many references to other related resource materials for those seeking additional or more detailed information. This guidance begins with an overview of the extent and types of nonpoint source problems reported by the States and Tribes. The overview is intended to provide perspective and set the stage for the chapters that follow. Subsequent chapters describe the basic steps involved in designing a nonpoint source monitoring plan, including sections and chapters devoted to biological, photopoint, and land use monitoring. A chapter that focuses on ways to address the many unique challenges associated with nonpoint source monitoring is also included. The chapter on data analysis describes and illustrates techniques ranging from exploratory data analysis to advanced statistical approaches for assessing the effectiveness of both individual best management practices and watershed projects. Pollutant load estimation methods are also described in detail. A chapter on quality assurance and quality control is then followed by a chapter addressing monitoring costs. Good monitoring design begins with a clear monitoring objective and an understanding of the water quality problem or concern addressed. Because problems and objectives vary, there is no single approach that can be applied to nonpoint source monitoring efforts. It is hoped this guidance provides a foundation that allows practitioners to design monitoring programs that meet their unique needs. Readers are encouraged to consult the many resources listed in this document. In addition to these resources, readers are urged to contact monitoring and quality assurance experts in academia and at the local, State, Tribal, and federal levels for assistance in developing monitoring plans and analyzing the collected data.