Tualatin River Watershed

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Water Supply Feasibility Study: Fisheries PREPARED FOR: Lisa Obermyer, Montgomery Watson Harza PREPARED BY: Greg White, CH2M HILL COPIES: Tom VanderPlaat, Clean Water Services DATE: July 16, 2003 Introduction The Tualatin River Watershed has seen a number of changes in recent years that influence water resources management. These include population growth and new regulatory requirements under the Clean Water Act and the Endangered Species Act. In an effort to respond to these changes, the Water Managers Group, a group of public and private entities consisting of the Joint Water Commission, Lake Oswego Corporation, Tualatin Valley Irrigation District, City of Tigard, Tualatin Valley Water District, Clean Water Services…show more content…
Hagg Lake, with a storage capacity of 53,600-acre feet, is the impoundment created by Scoggins Dam. Hagg Lake water is currently used for river flow restoration, municipal water supply and agricultural irrigation needs throughout the Watershed. The reservoir has park and recreation facilities operated by Washington County. The Water Supply Feasibility Study addresses aspects of raising Scoggins Dam by 20-feet and by 40-feet. Raising Scoggins Dam would affect tributaries to Hagg Lake as well as Scoggins Creek downstream of Scoggins Dam. Therefore, the Project Area includes areas potentially inundated by the increased size of Hagg Lake as well as Scoggins Creek downstream of Scoggins Dam. Anadromous salmon and trout as well as resident fish species and Species of Special Concern (state or federal) occur within the Project Area. Methods Sources of existing fisheries information and data included the Oregon Rivers Information System (ORIS); StreamNet; Oregon Natural Heritage Program; Oregon Department of Fish and Wildlife (ODFW) project area files, reports, and data; Clean Water Services (CWS);…show more content…
A Recovery Plan for listed steelhead trout Evolutionary Significant Units (ESU’s) has not yet been developed. Without a Recovery Plan, the most appropriate approach for addressing activities that might adversely affect steelhead trout include considerations for protecting critical spawning and rearing areas. The NOAA Fisheries has designated critical habitat for the listed UW steelhead trout which encompasses all accessible reaches of all rivers and tributaries below longstanding naturally impassible barriers and specific man-made structures. Critical habitat for the steelhead ESU is designated to include all river reaches accessible to listed steelhead trout in the upper Willamette River and its tributaries above Willamette Falls upstream to, and including, the Calapooia River. Also included are adjacent riparian zones, as well as river reaches and estuarine areas in the Columbia River from a straight line connecting the west end of the Clatsop jetty (south jetty, Oregon side) and the west end of the Peacock jetty (north
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