Washington State Methods for Assessing Wetland Functions

Volume I: Riverine and Depressional Wetlands in the Lowlands of Western Washington

This document is the first volume in a series describing methods for assessing wetland functions in Washington. The first volume is divided into two parts. The first part contains background information and four assessment methods, one each for four wetland types (subclasses) occurring in the lowlands of western Washington. The second part contains procedures and field forms for collecting and recording the data needed to apply the methods. Read descriptions of each chapter below.

Download files

Part 1 can be downloaded in its entirety or divided into 2 smaller PDF files. Part 2 is in one PDF file. In addition, there are four Excel spreadsheets, one for each wetland subclass, that can be used to calculate the index of performance for each function. Instructions for using the spreadsheets are found in the "Read Me" file.

Part One

Part Two

Excel Spreadsheets

Changes and Clarifications (February 2001)

A document listing changes and clarifications to Volume I is available. Changes include general comments, as well as changes to specific pages, data, and parts of the data forms. Select one of the links below to download the Changes and Clarifications document. We are also providing replacements for selected pages.

Note - If you attended the first 5-day training July 12-16, 2000, you will need to use a different set of replacement pages for the Part 1 Methods document. Part 1 Replacement Pages - First Trainees (PDF)


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Description of each Chapter

The following is a brief description of the two parts.

Part 1

Chapter 1 — Chapter 1 is a brief description of the project, enough to provide a context for the assessment methods. It also includes a summary of the process followed, the wetland classification system used, and how reference wetlands were used in method development.

Chapter 2 — Chapter 2 describes the type of methods that were developed and the technical aspects of model building, such as calibration and normalization of the equations. The chapter ends with a summary of what the numeric results of the models represent.

Chapter 3 — Chapter 3 is an introduction to applying the methods in the field using photos, maps, and field data. The issue of dividing a wetland into smaller units to be assessed individually (called assessment units or AUs) is also introduced in this chapter. As described below, detailed procedures regarding completing fieldwork at the site to be assessed are provided in Part 2.

Chapter 4 — Chapter 4 describes how to apply the results of the methods in the context of wetland management. The chapter covers some of the applications for which the results can be used, how to interpret the results, other information that should be incorporated in decision-making, and tips for the decision-maker.

Chapter 5 — The functions that are being assessed are discussed in Chapter 5. The logic behind choice of functions and generalized definitions for each function are provided. The functions specific to each subclass are described in the chapters containing the methods.

Chapters 6 through 9 — Chapters 6 through 9 contain the actual methods for depressional outflow, depressional closed, riverine flow through, and riverine impounding wetlands in the lowlands of western Washington. Each method includes models for up to 17 individual functions. Within these chapters, each function model is described in its own section, and includes the following:

  • Definition and description of the function
  • Description of how the function is assessed for that subclass
  • Summary of the model ("Model at a Glance")
  • Description and scaling of variables

"Model at a Glance"displays the environmental processes or characteristics that are assessed for that function, the variables chosen to model that process, and any indicators of the variable if needed. Variables are defined at the bottom of the table and listed in alphabetical order. "Model at a Glance" tables also give the equations that are used to calculate the potential of the function being performed.

The summary of the calculations is presented in table format. These provide the scaling of the variables needed to compute the equations. A description of the scaling, any calculations needed to determine the scaling, and the resulting score for each variable is displayed. The field data for each variable or, where needed, the indicators used in the calculations for scaling are numbered to correspond to the field data sheets. The equation for the model is repeated here so that the scores can be inserted in the equation and the numeric index of performance or habitat suitability can be computed.

Miscellaneous —Part 1 ends with a glossary, cited references, and appendices.

Part 2

Part 2 contains the detailed procedures for collecting the data to complete the assessments. It describes how to gather information including maps and photographs, organizing the field equipment needed, and previewing information prior to visiting the site. Part 2 also provides guidance for determining if multiple assessment units are needed within a contiguous wetland boundary.

The bulk of the volume consists of the detailed procedures for collecting each datum for the assessment. Data sheets for each subclass are provided in the appendices, along with other tools.

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