Fish Passage Barrier and Surface Water Diversion Screening Assessment and Prioritization Manual


This document is provided for archival purposes only. Archived documents do not reflect current WDFW regulations or policy and may contain factual inaccuracies.

Category: Guidelines

Published: December 2009

Pages: 240

Author(s): Mike Barber, Susan Cierebiej, David Collins

The Fish Passage Barrier and Surface Water Diversion Screening Assessment and Prioritization Manual provides guidance on how to locate, assess, and prioritize fish passage problems (culverts, dams, and fishways) and surface water diversion screening problems. These science-based protocols are well accepted and provide a consistent approach to determine a fish passage barrier. We encourage all parties assessing culverts to use the WDFW fish passage and screening assessment protocols and to share their data for inclusion in the statewide database.


This manual was originally written in 1998 to provide a standardized methodology for evaluating fish passage at road crossings. The manual has since been expanded to include evaluation of additional instream features, including dams, fishways, other human-made instream structures, natural barriers, and surface water diversions. Revisions to the prior version of this manual (August 2000) are summarized in Table 1.1. A glossary of words, terms, and abbreviations used in this manual can be found in Appendix A.

1.1 Purpose

This manual is intended to provide guidance for conducting fish passage and surface water diversion inventories. Fish passage inventories lead to identification and assessment of instream features and prioritization of fish passage barriers based on amount, quality, and species utilization of habitat upstream of the barrier. Surface water diversion inventories allow for the identification, assessment, and prioritization of unscreened or inadequately screened diversions in need of correction.

1.2 Overview

This chapter introduces the general inventory concepts and discusses inventory planning. The second chapter of the manual covers information needed to describe the location, fish use, and ownership information for each site evaluated for fish passage and/or screening. Chapters 3-8 describe data collection and methods for evaluating different features encountered during the inventory. Finally, chapters 9 and 10 cover habitat assessment methods and prioritization for fish passage and screening projects, respectively.

The methods described herein have been widely used since the late 1990s by Washington Department of Fish and Wildlife (WDFW), tribes, local governments, the Salmon Recovery Funding Board (SRFB), regional fisheries enhancement groups, and others. WDFW provides training on the protocols contained in this manual to groups conducting inventories.

WDFW maintains a database of data collected using the protocols described in this manual. The WDFW Fish Passage and Diversion Screening Inventory (FPDSI) database functions as a central repository for information resulting from inventories conducted throughout the state. This information can be used to select and implement fish passage and screening projects vital to the recovery of Washington's salmonids.




Details of the update

Chapter 3

Road Crossing Structures - Culverts

Added table for guidance in estimating the percent passability for barrier culverts. Also includes photo examples of different road crossings.

Chapter 3

Non-culvert Road Crossings

New section.

Chapter 3

Level A flow chart

Updated flow chart of the Level A culvert analysis.

Chapter 3

Photo Examples

New figures, including photo examples of different road crossing structures, and tide and flood gates.

Chapter 4


Expanded discussion on dams, including feature description and evaluating fish passage. Added data collection attributes table. Included photo examples of different dam structures.

Chapter 5

Miscellaneous Obstructions

New section on ‘Other’ human-made fish passage features (that are not classified as culverts or dams). Includes photo examples of miscellaneous obstructions.

Chapter 6

Natural Barriers

New section.

Chapter 7


Added section on evaluating fishways associated with culverts, dams, and other features. Included data collection attributes table.

Chapter 7

Photo Examples of Fishways

New figure.

Chapter 8

Surface Water Diversion/Screen Evaluation

Updated text, figures, and data collection table. Includes photo examples of common screens.

Chapter 9

Habitat Assessment

Eliminated the Expanded Threshold Determination (ETD) option for estimating habitat gain. This method had a very low confidence level due to several factors. A map-based assessment does not identify additional upstream and downstream human-made barriers, or natural barriers that may prematurely end a habitat survey. The actual length of fish bearing waters is difficult to accurately assess using the map-based method, leading to the possibility of overestimation or underestimation of actual habitat.

Chapter 9

Physical Habitat Survey

Discontinued using the term Ordinary High Water (OHW). Now using the term Scour Line Width (SLW), referring to one of the channel width measurements taken for making fish passage and habitat assessments. Refer to Glossary in Appendix A for definitions of terms.

Appendix A

Glossary of Terms


Appendix B

Recommended Equipment List


Appendix D

Measuring Channel Width (Appendix H from the Design of Road Culverts for Fish Passage)


Appendix E

Basic Culvert Surveying Techniques


Suggested citation

Washington Department of Fish and Wildlife. 2009. Fish Passage and Surface Water Diversion Screening Assessment and Prioritization Manual. Washington Department of Fish and Wildlife. Olympia, Washington.