Function of Large Woody Debris

Restoring Salmon Habitat with Large Woody Debris

Isaac Sanders – Stream Restoration Biologist Oregon Dept. of Fish & Wildlife/Clackamas Stream Restoration with Large Wood Placement Topics to be covered…

 Why Large Woody Debris (LWD)?  Function of LWD in maintaining “Habitat Complexity”  What is large wood?  Completed North Fork Gales Creek LW project  Proposed SFK to NFK Gales Creek LW Project

What is large wood?

 ODFW Aquatic Inventory survey protocol defines large wood as at least 15cm (6”) in diameter and 3m(~6’) long  Key pieces need to be at least 60cm (~24”) in diameter and 10m (~33’)

ODFW Habitat Benchmarks

Large Woody Debris (15cm x 3m Undesirable Desirable minimum size) Pieces/100m Stream Length <10 >20 Volume/100m Stream Length <20 >30 “Key” Pieces (>60cm x 10m long/100m) <1 >3 What is Large Wood?

 ODF/ODFW Guide to Placing Large Wood recommends wood to be 2 times the width of the stream or 1.5 times the width if it has attached rootwad.  The slope of the stream should fall between 2- 15% depending on stream width.  Information summarized in next slide

LWD Size Chart Bankfull Width (feet) Minimum Diameter Slope of wood (inches) 0-5 Not addressed here. Large wood placement typically does not occur in very small streams 6 10 <15% 8 10 <12% 10 10 <10% 12 16 <9% 14 16 <7% 16- 18 16 <6% 20 16 <5% 22 18 <5% 24- 26 18 <4% 28- 30 18 <2% 32- 40 22 <2% 42+ Bankfull width exceeds “acceptable” conditions.

Why Large Woody Debris? . Lack of large wood can lead to; . Loss of structure in channel (gravel, cobble, wood) . Higher water velocities . Limited spawning and rearing opportunities

 Loss of riparian cover  Over-steepened banks  Bank failure and excessive erosion Maintaining Habitat Complexity – Function of Large Woody Debris

 LWD acts to stabilize stream channels by reducing water velocity, creating pools, and reducing bank erosion.  Provides cover, resting and feeding areas for juvenile fish.  Traps gravel and nutrients (salmon carcass, detritus).  Sorts fine and coarse sediments.  Increases habitat complexity

. Gravel accumulation creates spawning habitat . Slower water velocities . Large wood and channel structure is maintained  Structures trap other material to create jams

. Pools and riffles are maintained

North Fork Gales Creek Project North Fork Gales Creek Project

 Project location identified by Tom Murtagh as ideal for large wood placement  Critical habitat for Endangered Steelhead  Lower ½ of project in State Forest, upper ½ on Stimpson timberland  Creek reach surveyed in 1993 and little has changed in 16 years  Lacking in LW, channel complexity and pool habitat (less than 20%), abundant riffle habitat (over 60%  Pieces/100m boarder line at 22 (AQI benchmark >20)  LW volume/100m low at 16.6 (AQI benchmark >30)

North Fork Gales Creek Project

 April approached landowners with the project  Landowners agreed to project and provided the large wood and permitting  OWEB grant applied for in fall of 2008, received in spring of 2009, project implemented late summer 2009, tree planting spring 2010.  Aquatic Contracting fell, transported and placed the ODF trees and placed the Stimpson wood

. ODF provided 50+ Douglas Fir trees within 1 mile of the project location along Plantation Road . Stimpson Lumber provided 25 logs and transportation.

NFK Gales tree tipping Logs transported with “self- loading” log truck to staging areas

Logs staged by NFK Gales Creek Road. Aquatic Contracting assessing the situation Pre-treatment site on NFK Gales

.Post-treatment site on NFK Gales .Pre-treatment site on NFK Gales

.Post-treatment site on NFK Gales Pre-treatment site on NFK Gales

.Post-treatment site on NFK Gales .Pre-treatment site on NFK Gales

.Post-treatment site on NFK Gales

Thank you!

Isaac Sanders ODFW-North Willamette Watershed District 17330 SE Evelyn St. Clackamas, OR 97015 (971) 673-6033