1

Restoration Techniques forThree High Gradient Tributaries

in Karnowsky Creek, Oregon Coast Range

River Restoration Northwest SymposiumSkamania, WA

January 30 – February 2, 2006

Johan B. HogervorstHydrologist, Siuslaw National Forest

• General overview of the project

Karnowsky Creek Stream Restoration

• Techniques we’ve tried in twointermittent channels

• Lessons learned for each channel

2

KarnowskyWatershed

SiuslawEstuary

FlorenceMapleton

Karnowsky Creek,Lower Siuslaw Watershed

Karnowsky Valleypre-project condition

Siuslaw River

Duncan Inlet

PrivateUSFS

Head of Tide

OriginalHomestead

1932

Tidal Influenceon Private Land

Ditches

Drained pastureland

Deeply incised ditches

3

Karnowsky Creek Stream Restoration

Private

USFS

Head of Tide

OriginalHomestead

Aggraded Reach

Down cutDown cut

Flow

Main Stem Restoration Objectives

• Restore water table/wetland habitat

• Reconstruct a meandering channel that regularlyconnects with its flood plain

• Reestablish native vegetation• Create complex fish habitat through

addition of large wood

• Work with a collaborative partnership in the Siuslaw Basin

Karnowsky Creek Stream Restoration

1.5%

MaintainExistingSpawning

.65%

.1%

Lower Two Miles of Main Stem Channel

4

Fall, 2002Fall, 2003Spring, 2004

Channel

Wood

Floodplain

Hummocks

Karnowsky Creek Stream RestorationTributary Restoration Objectives

• Demonstrate results to private landowners

• Reestablish natural gravel transport

• Create additional fish spawning areas

• Reduce/eliminate excessive bank erosion

• Recover water table to enhance ephemeral flow

Tributary #2

Tributary #3

UpperMain Stem

Tributary #1Tributary #1Tributary #1

• Work with a ditch that is not severely incised

• Recreate meanders where bank erosionis attempting to form them

• Reconstruct channel where a remnanthistoric channel exists

• Raise bed level of ditch where goodroot strength in banks exists

5

Tributary #1, 2003

Old

New

Meander Reconstruction

Cedar buriedat grade

Cedar keyedinto bank

12

34 5

6

Fill and Capwith rock

400 feet of newChannel construction

Filled Ditch

New Channel

Tributary #1 Pre- and Post-treatment long profiles, 2003

3035404550556065707580

0 500 1000 1500

Slope Dist (ft)

Elev

atio

n (ft

)

BeforeAfter

1 2 3 4 56

1.4%

2.0%

1.7%

New Channel@ 1.4%

6

Tributary #1 - Meander construction

Sept, 2003

Tributary #1 - Meander construction

7

Tributary #1 - Meander construction, wood at grade

Tributary #1,Meander construction,

Wood at grade

8

Sept, 2003

Tributary #1,Meander

construction,wood at grade

Ditch to befilled & capped

with rock

Buried wood being finished

New MeanderOld Ditch

Finishing upper meander #6 and Ditch Fill/Cap section

Sept, 2003

9

Winter flow, meander #6 – upper end

Buried wood

January 7, 2004

Winter flow, meander #6 - middle

January 7, 2004

10

Winter flow, meander #6 – lower end

January 7, 2004January 3, 2006

Buried Wood

December 1, 2005

Tributary #1,Meander #5,

keyed-in woodat high flow

Cedar log

11

Tributary #1, Meander #3, keyed in wood

January 19, 2006

Buried wood

January 19, 2006

Wood jam

Tributary #1, Meander #2, gravel accumulation

12

Tributary #1 - Partial ditch fill capped with rock

January, 2004January, 2006January, 2006

Tributary #1 – Lower 400’ of channel construction

Sept, 2003

13

Tributary #1,Lower channel Gravel seeding

• No wood at grade inthis channel

• Gravels weresprinkled in channel

Sept, 2003

Sept, 2003

Reference TreeReference Tree

January 7, 2004

Lower Tributary #1- channel construction

14

• Wood keyed into banks and bed workedwell for stability of meanders. Bed erosion occurred without wood in newchannel section.

• New meanders built off of slightly entrenched channel doing well. Bank erosion reduced.

• Substrate currently moving throughthe system.

Tributary #1 observations & lessons learned

• Gravel seeding in newly constructedchannel must account for shear stressand proper substrate size.

• Partially filling the ditch and cappingwith rock worked well where there was existing root strength in banks.

• New alluvial fan area at the bottom isstill evolving.

Tributary #1 observations & lessons learned

15

Karnowsky Creek Stream RestorationUpper Main Stem Restoration Objectives

UpperMain Stem

• Build new channel to replace extremely incisedditch in upper valley

• Work with existing pieces of old channel,which have historic meander geometry

• Learn from lessons of Trib. #1

• Incorporate valley gradient changesinto new channel

90 0 90 180 270 Feet

N

EW

S

Upper Main Stem Channel, 2002-2004

Winter 2004/2005 – first flow

2003 & 2004 – treated riffles with gravel and wood, armored pool tail crests

2002 – initial construction

Fan #4Fan #3

Regrade

Fan #1

Fan #2

Diversion pond/structure

2004 – plugs placed in ditch andponds connected to main channel

16

Main stemflow

Ditch

Diversion Plug – 2004 Tributary

New Channel2002

2003REGRADE

Stockpile2003

Stockpile2003

Channel Connected2003

POND

Diversion from Ditchinto new upper Channel

Karnowsky Upper Channel Post- Construction Long Profile, 2004

70

75

80

85

90

95

100

105

110

0 500 1000 1500 2000 2500

Slope Distance (ft)

Elev

atio

n (ft

)

2004

0.3%1.6%

0.8%1.6%

0.5%1.1%

1.04%

17

Upper Channel Construction

Upper Channel Construction

18

Winter Flow, January 2006

Main stem Side trib.

New channel

Scour holes in remnant channel section

19

Upper Channel Wood

Built up outsidemeander

CorrespondingPoint bar Buildup

Upper Channel observations & lessons learned

• Don’t short circuit the gravel transport. Gravelscoured at the top end of the channel is notbeing replaced due to pond deposition.

• Diversion pond is filling and will likely reconnect gravel transport in the first 5 yearsafter water release.

• Transitions from vegetated to non-vegetatedbed were problematic. Wait an extra year?

20

• Steep remnant sections show most scourat this point in time.

• Losing some pool tail crests. Proper substrate size is hard to obtain but is criticalto success.

• Lower half of channel looks very goodincluding flood plain inundation during highflow. Point bars are building but pools are allmaintaining.

Upper Channel observations & lessons learned

In SummaryReconstructing channels at slopes greater than1.5% can be very challenging. It takes lots of

planning, thought and iterative design.

Rectifying severely incised channels is costly and labor intensive. Consider cost benefit.

Tributary #1 is stable and serves as a gooddemo for landowners.

The upper main stem channel is stilltransitioning and will be monitored.

21

Tributary #3 – Step pool channel, 2005

80 0 80 160 Feet

N

EW

S

Tributary #3

Entire DitchFilled

RemnantChannels

2.7% overall = step pool channel

Re-graded valley floor

22

Karnowsky Creek, Trib #3, Long Profiles, 2005 and 2006

7580859095

100105110

0 200 400 600 800 1000 1200Slope Distance (ft)

Elev

atio

n (ft

20052006

2.7%

Tributary #3 construction

Ditch Preparation

23

Tributary #3 – ditch filling