Introduction

From 1998 through 2001, the National Marine Fisheries Service (NMFS) provided research funding to evaluate fish passage at existing culverts. The goals of this project included:

• Identifying the range of flows over which anadromous salmonids migrate up smaller streams
• Evaluating the suitability of fish passage design flows
• Evaluating methods for estimating fish passage design flows in small, ungaged watersheds.
• Analyzing the performance of new culvert installations
• Assessing the performance of culverts retrofit with baffles or weirs

The original culvert on Morrison Gulch, a tributary to Jacoby Creek, was selected as one of our intensely monitored sites because of its challenging passage conditions and high population of coho salmon (Onchorynchus kisutch).

A new culvert meeting NMFS fish passage design guidelines was installed in October 2002 with funding secured by Humboldt County and the Redwood Community Action Agency from California Department of Fish and Game, Regional Water Quality Control Board, and the Coastal Conservancy.

This page summarizes findings from the initial study, describes the design and design constraints of the new culvert and presents results from our ongoing post-project monitoring.