Oroville Dam Spillways Emergency, February 2017 and Beyond

Presented to the California Water Commission on May 18, 2017

DWR State Water Project

Overview

Largest state owned & operated water

delivery system in the U.S. CA voters

said yes in 1960 BPA

Multiple Purposes and Benefits: water

supply, flood control, Delta WQ, fish and

wildlife preservation and enhancement,

recreation, and electric grid stability

Serves 25 million Californians & over

750,000 acres of farmland

32 Storage Facilities, 21 Pumping Plants,

4 Pumping-generating Plants, 8

Hydroelectric Plants, about 700 miles of

Canals and Pipelines

ASCE Project of the Millenium and

numorous other accolades

Over 190 MAF delivered, over 200 million

recreation user days, and significant flood

control protection

SWP Facilities

SWP Beneficial Uses of the Feather River Local Senior Water Rights Supply, SWP Water Rights Conditions/Supply, Fish and Wildlife Preservation, and Flood Protection

Meet local water supply

contractual requirements

(superior water rights)

Specifically to support SWP

water supply deliveries

Meet Delta WQ requirements

(SWP water right permit req)

Flood control USACE Rule

Curve

Meet instream requirements

for flow/temp specifically for

endangered salmonids

SWP Oroville Facilities

hydropower generated

subordinate to the requirements

above (some peaking flexibility)

112 Year Hydrologic Record

of Feather River Watershed

Annual Runoff

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TAF

Annual Unimpaired Runoff from the Feather River

Distribution of Landfalling Atmospheric Rivers on the U.S. West Coast (From 1 Oct 2016 to 12 April 2017)

Ralph/CW3E AR Strength Scale Weak: IVT=250500 kg m1 s1

Moderate: IVT=500750 kg m1 s1

Strong: IVT=7501000 kg m1 s1

Extreme: IVT>1000 kg m1 s1

AR Strength AR Count*

Weak 12

Moderate 21

Strong 13

Extreme 3

49 Atmospheric Rivers have made landfall on the West Coast thus far during the 2017 water year (1 Oct. 12 April 2017)

This is much greater than normal 1/3 of the landfalling ARs have been strong or extreme

*Radiosondes at Bodega Bay, CA indicated the 1011 Jan AR was strong (noted as moderate based on GFS analysis data) and 78 Feb AR was extreme (noted as strong)

By F.M. Ralph, B. Kawzenuk, C. Hecht, J. Kalansky

Water year 2017 AR landfall

locations through 11 April 2017

Location of landfall represents position where AR was strongest at landfall . Many ARs move down the coast over time. This map does not show these areas.

Wettest Year in Northern Sierra 8 Station Index History 97 years

Northern Sierra Snow Water Content Comparison in Wet YearsSignature of higher snow level storms very evident in 2016-2017

How wet has 2016-2017 been?

Sacramento Valley 8 Station wettest year in 97 year record Jan and Feb total precipitation was 46 inches Previous record was 40 inches

Inflow into Lake Oroville February was 540% of average Jan/Feb inflow was 4.4 MAF (= average annual)

Previous high was 3.48 MAF in 1909 Recent highs: 3.19 MAF in 1986; 3.07 MAF in 1997

Released the entire volume of the Lake (3.5 MAF) in 6 week period beginning in mid-Jan

Impaired gated spillway will have released almost 5 MAF since 2/7/17, more than twice any year in history

Inspection of Initial Spillway Deck and Foundation Erosion February 7, 2017

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Damage after Flows Resumed on Feb. 8th, 2017 400 feet of headcutting in the first 24 hours 11

February 9th aggressive headcuttingcontinues, threatening Hyatt 230 Kvtransmission tower and entire line

The Dilemma what is the safe discharge of the gated spillway to preclude erosion encroaching on the gate structure and thus requiring permanent closure?

Gated Control Spillway at 55,000 cfs on 2/10/17, erosion had significantly slowed but not one expert in the joint command group believed it had stopped Emergency Spillway Grouting/Clearing/Grubbing Underway

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Debris Dam Diversion Pool on February 27, 2017 1.7 MCY

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Debris Dam in the Diversion PoolFebruary 27, 2017

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Working to clear a HPGP Tailrace ChannelFebruary 28, 2017

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Edward Hyatt Powerplant

Sandbagging Efforts by DWR Staff

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Edward Hyatt Powerplant

Sandbags Placed to Protect Equipment

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2017 Oroville Spillways Emergency Response and Recovery

Ongoing Response and Recovery: Protect the public, property, and all those responding to this emergency Continued Collaboration with State, Federal, and Local Agencies Diversion Pool Debris Clean-Up, >1,600,000 cy removed, more importantly

over 1 million cubic yards removed between 2/27 and 3/5! $274 million emergency response estimate provided to CalOES and FEMA

for February thru May 2017 costs (Recovery $s are separate) $150 million expended to date for debris removal, ES work, Hyatt flood fight, etc. Many emergency response work invoices still not submitted

Hyatt Powerplant Operations 5 units generating as of 3/9/17 after one month outage due to high tailrace WSEL flood threat Penstock 1 outage (U1-3) for annual maintenance 4/14-5/23

Drilling Gated Control Spillway slab and foundation data suggests much of upper chute w/thicker slab than as-built drawings show

Construction contract for Burma Road awarded to Teichert work underway for important construction access roads for $5.8 million

Spillway re-construction contract awarded to Keiwit Pacific for cutoff wall on ES, and RCC replacement of lower concrete chute for $275 million

Environmental and Cultural Collaboration/Assessments ongoing 18

Comparison of Lake Oroville Gated Control Spillway

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