Upper Truckee River Restoration

Lake Tahoe, California

Presented by Brendan Belby – Sacramento, California

Mike Rudd (Project Manager), Charley Miller & Chad Krofta

Declines in Tahoe’s Water Clarity

Source: Tahoe Resource Conservation District, 2003

The Upper Truckee River watershed viewed from its headwaters near Carson Pass north towards Lake Tahoe

• Comstock Era Logging & Mining

• Grazing

• Urbanization

• Channelization

• Floodplain Encroachment

Historic Land Uses

Source: USDA, Lake Tahoe Watershed Assessment, 2000

Historic Large-

Scale Logging

• 60% of Tahoe Basin

was clear-cut

• 95% is second growth

forest

Source: Photo by Dr. Robert Orr, property of California Tahoe Conservancy

Upper Truckee Marsh in 1930

Tahoe Keys

Upper Truckee River

Trout Creek

Upper Truckee Marsh Today

# homes

increased 500-

19,000 from

1960-1980

Source: Steve Winter, M.S. Thesis, U.C. Davis, 2003

Sediment Accretion Rates

•Logging: +600%

•Urbanization: +350%

Planform Adjustments to Sediment Supply

1940 2003

Sedimentation in response to logging?

Minimal planform change reflection of low energy &

cohesive meadow soils

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

01/01/71 12/31/73 12/30/76 12/30/79 12/29/82 12/28/85 12/27/88 12/27/91 12/26/94 12/25/97 12/24/00

Date of Measurement

Ele

va

tio

n (

ft a

bo

ve

fix

ed

da

tum

)

0

500

1000

1500

2000

2500

3000

3500

Me

an

Da

ily F

low

(cfs

)

pzf

Mean Daily Flow

Profile Adjustments to Sediment Supply

Bed elevation changes in response to urbanization?

Channel Response

Downcutting

•Doubling of channel capacity

•Lacustrine layer exposure

Channel Response

Bank Erosion

•Sod blocks

•Fine-grained sediment input

Channel Response

Aggradation/Widening

Incipient Floodplain

•New depositional landforms

•Lower base level

•Slow development

Taken 5/5/04 at ~350 cfs, RS 16000

Existing Condition:

•Slope: 0.001

•D50: 4 mm

•Width: 65 ft

•Depth: 5-6 ft

•Capacity: 700 cfs (2-yr RI) to1,300 cfs (5-yr RI)

American Forests 1935

“Crooked streams are

a menace to life… Du

Pont Dynamite has

straightened many

thousands of miles of

crooked streams…Du

Pont has an explosive

for every purpose”

Reaches 3 & 4 – Airport Reach

Clients: City of South Lake Tahoe and

California Tahoe Conservancy

May 17, 2005 Flood

Upper Truckee River – Reaches 3 & 4

Reaches 3 & 4

New Channel

Construction

Started in

Summer 2008

Source: City of South Lake Tahoe

•Reduce channel capacity to increase overbanking•Increase deposition & storage of fine suspended sediment•Decrease bank erosion•Raise groundwater levels•Improve habitat

Major Project Goals

Alternative 1 – Existing Channel with Habitat Improvements

1.Construct in-channel habitat structures and bank stabilization features

2.Locally narrow channel at locations with large wood, vegetated bars, or ledges to create a more sinuous flow path

3.Construct an inset floodplain to enhance overbanking

Alternative 2 – Construct New Channel with Airport In-Place

1.Construct ~4,000 ft of new meandering channel

2.Re-grade airport terrace fill to create a new floodplain

3.Build large woody debris features for habitat improvement

4.Work within the constraints of the airport and existing utility lines

Alternative 3 – Construct New Channel with Partial Airport Removal

1.Remove ~1,500 ft of airport runway for the new channel

2.Relocate sections of existing gravity and forced main pipelines

3.Construct ~4,800 ft of new meandering channel

Alternatives Ranking CriteriaObjective Desired Outcomes

Restore a more naturally functioning river and floodplain

Restore channel form in balance with hydrology and sediment supplyIncrease frequency of overbankingIncrease deposition of riverborne fine sediment and nutrients onto the floodplain.

Improve water quality by restoring natural stream and floodplain processes.

Reduce nutrient and fine sediment loads generated within the Project area or transported through the Project area.

Restore, enhance and protect aquatic and terrestrial habitat diversity and quality.

Enhance the habitat values of the river and floodplain for supporting native aquatic and terrestrial animals and plants.

Develop a cost-effective, timely and implementable design

Provide a cost-effective projectProvide a permittable projectMinimize time to project maturity and benefit

Floodplain Inundation

Modeling

760 cfs (2-yr Event)

Existing

Condition

0 acres

Future

Constructed

Condition

19 acres

Alternatives Ranking Criteria Example

Ranking

Scores

Channel & Floodplain Design

Design a channel and floodplain with an

appropriate morphology that is in balance

with the prevailing hydrology and sediment

regimes

• Measure transport throughout spring runoff

• Calibrate transport modeling with measurements

Bedload SupplyHow much bedload should the channel be able to

transport?

Measured &

Modeled

Transport

0.001

0.01

0.1

1

10

100

1000

0 100 200 300 400 500 600 700 800 900 1000

ENTRIX Meaured Bedload Transport (2006)

Modeled Bedload Transport - Wilcock (2001) Two-FractionCalibrated Method

Modeled Bedload Transport - Ackers & White (1973) with Proffitt &Sutherland's (1983) Hiding Function

Q (ft3/s)

Qs

(tons/day)

gravel t*rg = 0.01

sand t*rs = 0.03

Are t*c

values

reasonable?

Source: Wilcock and Kenworthy 2002

Upper Truckee River Effective Discharge - Based on Measured and Modeled Bedload During

Passage of a Sand Wave (High Transport Conditions)

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

50

74

98

122

146

170

194

218

242

266

290

314

338

362

386

410

434

458

482

506

530

554

578

602

626

650

674

698

722

746

770

794

818

Discharge (cfs)

Tota

l B

edlo

ad (

Tons)

Based on Ackers & White (1973) equation w ith

Proff itt & Sutherland's (1983) hiding function

applied at the Sunset Stables Bedload XS (RS

25+670) and all USGS gage #10336610 Mean

Daily Discharge from 1971-2005

Qeff = 398 cfs

Upper Truckee River Effective Discharge - Based on Measured and Modeled Bedload Without

Passage of a Sand Wave (Low Transport Conditions)

0

100

200

300

400

500

600

700

50

74

98

122

146

170

194

218

242

266

290

314

338

362

386

410

434

458

482

506

530

554

578

602

626

650

674

698

722

746

770

794

818

Discharge (cfs)

Tota

l B

edlo

ad (

Tons)

Based on Wilcock & Crow e (2003)

equation applied at the Sunset

Stables XS 26 (RS 24+540) and all

USGS gage #10336610 Mean Daily

Discharge from 1971-2005

Qeff = 398 cfs

Effective

Discharge

Analysis

Qeff = 400 cfs

Select

Design

Discharge

Equation: Huang and Nanson 1998 – (Qbf, S, n)

Bank Type Channel

Width (ft)

Moderately cohesive sand 44.5

highly cohesive sand 31.4

moderately vegetated and moderately cohesive sand 36.6

heavily vegetated and highly cohesive sand 26.7

Selected Design Width = 38 ft

How wide should the channel be?

Equilibrium Slope Analysis

0.00010.00020.00030.00040.00050.00060.00070.00080.00090.00100.00110.00120.00130.00140.00150.00160.00170.00180.00190.0020

20 30 40 50 60 70 80

Channel Width (ft)

Equili

brium

Slo

pe

2

3

4

5

6

7

Depth

(ft

)

Slope

Depth (ft)

How steep and deep should the channel be?

38 ft

Final Channel Design

Micro-

topography

Irregular

bends

Fill existing

channel

Construction – Summer 2008

Acknowledgements

• The City of South Lake Tahoe• The California Tahoe Conservancy• Mike Rudd - ENTRIX Project Manager• Charley Miller - ENTRIX• Chad Krofta - ENTRIX