2008 Annual Report Tualatin River Flow Management Technical
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TUALATIN RIVER FLOW MANAGEMENT TECHNICAL COMMITTEE 2008 Annual Report prepared by Bernie Bonn for Photo Credits: from left: Ki-a-Kuts Bike and Pedestrian Bridge, Tigard and sign on a bridge over the Tualatin River both photographs taken by Bernadine Bonn, July 2008 TTTUALATINTUALATIN RIVER F FLOWLOW MANAGEMENT TECHNICAL COMMITTEE 2008 Annual Report Prepared by: Bernie Bonn For: Clean Water Services In cooperation with: Oregon Water Resources Department, District 18 Watermaster FLOW MANAGEMENT TECHNICAL COMMITTEE MEMBERS Darrell Hedin, Secretary Oregon Water Resources Department Kevin Hanway City of Hillsboro Water Department Niki Iverson City of Hillsboro Water Department Jan Miller, Chair Clean Water Services Wally Otto Tualatin Valley Irrigation District Scott Porter Washington County — Emergency Management System Mark Rosenkranz Lake Oswego Corporation Chris Wayland Washington County Parks — Hagg Lake Randy Smith City of Forest Grove Jean Woll Joint Water Commission ACRONYMS USED IN THIS REPORT FULL NAME ACRONYM FULL NAME ACRONYM Facilities Units of Measurement Spring Hill Pumping Plant SHPP Acre-Feet ac-ft Wastewater Treatment Plant WWTP Cubic Feet per Second cfs Organization Micrograms per liter µg/L Barney Reservoir Joint Ownership BRJOC Milligrams per Liter mg/L Commission Million Gallons per Day MGD Clean Water Services CWS Pounds lbs (formerly Unified Sewerage Agency) River Mile RM Joint Water Commission JWC Water Year WY Lake Oswego Corporation LOC Water Quality Parameters Oregon Department of Environmental Quality ODEQ Biochemical Oxygen Demand BOD Oregon Department of Transportation ODOT Dissolved Oxygen DO Oregon Water Resources Department OWRD Sediment Oxygen Demand SOD Tualatin Valley Irrigation District TVID Tualatin Valley Water District TVWD U.S. Bureau of Reclamation BOR U.S. Geological Survey USGS Other Total Maximum Daily Load TMDL Wasteload Allocation WLA Disclaimer This report and the data presented herein are provided without any warranty, explicit or implied. The data presented in this report were supplied by the members of the committee. Although every effort was made to faithfully reproduce the data as provided, the data are not warranted to be accurate, appropriate for interpretation, merchantable, or suitable for any particular purpose. TABLE OF CONTENTS 2008 Summary . 4 Background Basin Description and Tualatin River Basin Map . 5 Tualatin River Water Management . 8 Member Reports for 2008 Reservoir Status . 9 Clean Water Services . 10 Joint Water Commission/Joint Barney Commission . 15 Lake Oswego Corporation. 18 Oregon Water Resources Department . 20 Tualatin Valley Irrigation District . 23 Water Quality Effects of Wapato Lake Drainage in 2008 . 28 Water Quality Status Report . 32 Appendices A. Stream Gage Records—Data Tables and Hydrographs of Daily Data B. Selected Releases and Withdrawals—Data Tables and Hydrographs C. Scoggins Reservoir (Henry Hagg Lake) Operations—Monthly Data Reports D. Barney Reservoir Operations—Monthly Data Reports E. Municipal Water Use Allocations—Monthly Data F. Temperature Records—Data Tables and Graphs of Daily Data G. Hagg Lake—Benthic Invertebrate Monitoring 2008 H. Precipitation Records— I. River Mile Indices— 2008 Tualatin River Flow Management Report 3 2008 SUMMARY This is the twenty-first year that the Tualatin River Flow Management Technical Committee has prepared an annual report documenting the flow management of the Tualatin River. Members of the committee include Clean Water Services (CWS), Tualatin Valley Irrigation District (TVID), Joint Water Commission (JWC), Lake Oswego Corporation (LOC) and Oregon Water Resources Department (OWRD). Highlights for 2008 include: • Both Barney and Scoggins Reservoirs filled. Tualatin River at Farmington (RM 33.3 #14206500) 1989–2008 13000 2008 1996 10000 2001 Statistical Distribution 1989–2008 90th percentile 75th percentile 1000 25th percentile Daily Mean Discharge (cfs) Discharge Mean Daily 10th percentile 100 60 1/1 2/1 3/1 4/1 5/1 6/1 7/1 8/1 9/1 1/1 10/1 11/1 12/1 Date • Damage to the Wapato Lake levee from a major storm in December 2007 prevented draining the lake in early spring as usual and created water quality problems in the Tualatin River (see pg 17 and 28). • The same December 2007 storm left considerable debris in Hagg Lake and its tributaries, which necessitated significant clean-up efforts in 2008. • Prompted by a new understanding of earthquake hazards in the area and the potential dam raise, new seismic studies of Scoggins Dam were conducted in the summer and fall of 2008. • A major snowstorm occurred in late December 2008, depositing more than 5 feet of snow in the upper basin. 4 2008 Tualatin River Flow Managment Report BACKGROUND Basin Description The Tualatin River Basin comprises an area of 712 square miles situated in the northwest corner of Oregon and is a subbasin of the Willamette River. The headwaters are in the Coast Range and flow in a generally easterly direction to the confluence with the Willamette River. The basin lies almost entirely in Washington County. (See map below) The Tualatin River is about 80 miles long and changes dramatically from its headwaters to its mouth. The mountain or headwater reach (upstream of RM 55) is narrow (about 15 ft) and steep with an average slope of about 74 ft/mi. The meander reach (RM 55–33) is wider with an average slope of about 1.3 ft/mi. The reser- voir reach (RM 33–3.4) is very wide (up to 150 ft) and has an estimated slope of only 0.08 ft/mi. It includes several deep pools. Travel times through this reach are very long. The slow movement of the water causes this reach to act much like a lake. In the riffle reach (RM 3.4–0), the Tualatin River flows through a short reservoir section and then drops into a narrow gorge near the City of West Linn before it enters the Willamette River just upstream of Willamette Falls. The average slope in this reach is 10 ft/mi. Tualatin River Basin 123°22'30'' 123°15' 123°00' 122°45' 122°37'30'' 26 WASHINGTON COLUMBIA 45°45' E a s W t e s t T U E A WASHINGTON G L C k A F e O N o r e T k r MULTNOMAH L F C I U A Gales o N M r k B R IA R IV M W E R O I L C North U r Banks L ee Plains N A TILLAMOOK k T M E A T OREGON y I T a N E K S D c 5 a M T ir y ek S re C k C re e A ek e n S r so c C on k O o Cornelius Hillsboro r e g B re g Forest C C RM k in c ill s Grove 50 o Bea R ve r M 26 Henry rt a on ed 45°30' Hagg Dilley C R ternut Cr Creek Lake UALATIN IVER ut T B Beaverton RM R I RM C RM Creek 40 V 60 E 70 Cherry H F ense a R Grove E ris t n C Farmington n Ch ree n H k o C A k RM Tigard r ee e Lake Ba L r 30 ek si E rris C Oswego n Bu RM bou M Scholls nda Creek 20 RM ry o 10 g M M l cF e ee a O w n Cr s a U B Tualatin O C N a r YAMHILL k rg C n e T e Nyb 205 o r A t k C e I a e N r r S e C H n Sherwood West e Linn Portland k ic Study C h RM area 0 OREGON CLACKAMAS N T 0 510 MILESI T A E T R N 0 5 10 KILOMETERS R U A O P 5 M 45°15' Base modified from U.S. Geological Survey 1:100,000 topographic quadrangles, 1978–84 Designated urban growth area from Metro, 1998 RM River mile 10 2008 Tualatin River Flow Management Report 5 Water sources to the Tualatin River Precipitation: Seasonal rainfall accounts for most of the natural flow in the Tualatin Basin; stream flow from snowmelt is minimal. The amount of rainfall ranges from 110 inches on the eastern slopes of the Coast Range to 37 inches in the southeastern area of the drainage basin. Peak months for rainfall are November through February while the driest months are normally June through October. The peak streamflow month is usually February and the lowest streamflow month is August. Barney Reservoir: Barney Reservoir is located behind Eldon Mills Dam on the Middle Fork of the North Fork of the Trask River (outside of the Tualatin Basin). A trans-basin aqueduct carries water over a low Coast Range divide to a pipeline that discharges into the Tualatin River at RM 78. Barney Reservoir has a capacity of 20,000 acre-feet and stores water for the Joint Water Commission (Cities of Beaverton, Hills- boro and Forest Grove and the Tualatin Valley Water District) and Clean Water Services. The Barney Res- ervoir Joint Ownership Commission owns, operates and manages Barney Reservoir. Reservoir content is monitored through calibrated reservoir elevations; water releases are monitored using a stream gage located in the outlet flume. Water is released during the summer low-flow season to supplement shortages in natural flow. The water is used for municipal supply and for instream water quality. Scoggins Reservoir: In the early 1970's the U.S. Bureau of Reclamation built an earthen dam on Scog- gins Creek (RM 5.1). Releases from Scoggins Reservoir (Henry Hagg Lake) flow down Scoggins Creek and enter the Tualatin River at RM 60.0. Scoggins Reservoir has an active storage capacity of 53,640 acre-feet.