Community Partner

Columbia Land Trust

First Advisor

Vivek Shandas

Date of Award

Fall 2011

Document Type

Project

Degree Name

Master of Environmental Management (MEM)

Department

Environmental Science and Management

Language

English

Subjects

Restoration ecology -- Oregon -- Clackamas River, Clackamas River (Or) -- Channels, Salmon -- Habitat -- Oregon -- Clackamas River, Ecosystem services, Floodplain ecology -- Oregon -- Clackamas River

DOI

10.15760/mem.18

Abstract

Natural areas and ecosystem services at the edge of urban areas are threatened by increasing development. This paper examines how community based restoration partnerships can work to identify, protect and restore ecosystem services provided by salmon and our local rivers. Floodplains provide a wide range of ecosystem services to urban and rural communities and we should work collaboratively to protect and restore them. Floodplains are especially valuable and important for salmon recovery. By using a case study, we explore the process and feasibility of restoring off-channel salmon habitat at Fisher's Bend in the lower Clackamas river. A feasibility study was conducted to identify costs, benefits and risks of different design alternatives for the side channel. Hydrology of the river and hydraulics of the site were determined by estimating peak and low flow hydrology then running a HEC-RAS hydraulic model. Results indicate that the river overflows into the side channel near the 2 year recurrence interval. On average there is currently about a 50% chance each year that the river will enter the side channel. These current flows do not provide much opportunity for juvenile salmon to access the side channel where they can grow and thrive in a protected habitat before their journey to the ocean. Further investigation produced results that indicate 95% of the time from 1959-2009 the river discharge was above 726 cfs from October to June. These results highlight that we will need to excavate about 9 feet from current elevations at the side-channel outlet to gain reasonable assurance of a one foot water depth for good salmon access. This depth will provide access from the river during critical periods when adult and juvenile salmon are seeking refuge from predators and high flood flows in the main channel. Although more design is needed for the inlet and outlet it appears the project is feasible and will meet the objective of providing salmonid access to critical habitat. In closing, I recommend investment in natural area protection and restoration at the edges of the urban growth boundary to maintain valuable ecosystem services provided by river floodplains and salmon.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Comments

Funding for this project was provided by the Oregon Watershed Enhancement Board and the Nature Conservancy‘s Salmon Fund in cooperation with Portland General Electric.

A project report submitted in partial fulfillment of the requirements for the degree of Master of Environmental Management.

Persistent Identifier

http://archives.pdx.edu/ds/psu/15764

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