Demonstration Reach Restoration Project Phases I and II

The Tribe's restoration of the Jocko River began with Phase I of the Demonstration Reach project in fall of 2004. The Demonstration Reach project continued with Phase II in fall of 2008. The Demonstration Reach was identified as an early priority for restoration because it was a significant sediment source located near the upstream end of the 22 mile restoration reach identified in the Jocko River Master Plan. This reach was also identified as a restoration priority because stream temperatures are generally suitable year round for all life stages of bull trout. The two phases of restoration address approximately two miles of the Jocko River channel and floodplain.

The Demonstration Reach of the Jocko River was channelized and diked approximately sixty years ago. These changes resulted in an incised channel that was disconnected from the floodplain. The first photo to the right shows the Jocko River through the downstream extent of Phase II of the Demonstration Reach before the completion of construction activities. The channel pattern is relatively straight and steep banks along the channel prevent regular access of flood flows to the floodplain as seen in the second photo to the right.

Anchored Coir Log

Anchored coir logs were installed along riffle-run sections to provide temporary bank protection and retain moisture along cobble dominated channel margins while native woody vegetation with deep binding root mass develops. Anchored coir logs were constructed on cobble benches and secured in place using duckbill earth anchors and wire cable. Both single and double layer anchored coir logs were constructed. Willow cuttings were installed vertically behind and between the coir logs.

Floodplain Connectivity

Raising the channel bed elevation improves connectivity with the floodplain surface. This also creates a surface where deep-rooted vegetation can establish and over the long-term provide bank stability, shading of the water, and many other important functions.

Brush Trench

Brush trenches were installed at some transitions between riffles and point bar features to provide roughness on newly constructed floodplain surfaces. Brush trenches encourage plant community succession on newly constructed floodplain surfaces by establishing woody vegetation that will produce seed sources, habitat and other riparian functions such as trapping fine sediment. Brush trenches are created by excavating a trench parallel to the channel approximately to the depth of baseflow or slightly lower. Willow cuttings, woody debris and low density coir logs are placed in the trench and the trench is back-filled to the floodplain elevation with alluvium. Willow cuttings placed in the trench extend between 1 and 3 feet beyond the finished grade surface. A similar technique, vegetated sills were also used in the Phase II project reach. Sills are similar to brush trenches, except they are constructed perpendicular to the channel rather than parallel along the channel. Vegetated sills were constructed in the newly constructed floodplain along one riffle feature in the project reach.

Preserved floodplain vegetation

Areas of existing floodplain vegetation were preserved in locations where floodplain surfaces were constructed. Preservation areas were left at the lower pre-project floodplain elevation, and in some cases filled with soil along the margins to create surfaces at an appropriate elevation where willows and cottonwoods could become established and expand these areas. Where possible, the floodplain was shaped to allow surface water to drain away from these areas to reduce ponding that might cause young cottonwoods and willows to drown. Over time, these areas are expected to fill with sediment to match the surrounding floodplain elevation.

Floodplain Microtopography

Floodplain microtopography including constructed swale features, placement of woody debris, and finished surfaces with undulating topography were utilized to create surface heterogeneity amd promote microsite for vegetation establishment. Swale features were incorporated into all constructed floodplain surfaces and were generally perpendicular to the channel. The bottom elevation of the swales is at baseflow or slightly above (approximately two feet below bankfull). Swales are irregularly shaped to mimic natural depressions and generally 25 feet long and eight to ten feet wide with 3:1 side slopes. Small to large diameter woody debris was placed in swales and on or partially buried in the floodplain surface. Rough graded floodplain surfaces vary between 0.5 feet above and 0.5 feet below the design floodplain surface elevation. Topsoil was placed on some constructed floodplain surfaces, primarily at outer meanders and some filled sections of abandoned channel to facilitate seed establishment.

Floodplain Bench

Behind wrapped coir logs, floodplain benches were constructed to establish bank margins that support riparian vegetation and tie into existing floodplain surfaces. These benches, along with most disturbed floodplain surfaces, were seeded and planted after construction activities. The benches behind most bank treatments (vegetated soil lifts and coir logs) had containerized plants installed using a stinger apparatus attached to an excavator. The stinger allows efficient plant installation in coarse textured substrate with little soil disturbance.

Log Jam

Engineered log jams were constructed on meander bends to provide temporary bank stabilization by reducing near-bank stress and redirecting flow away from the bank. These log jams were installed in association with bioengineering structures and other grade control and bank stabilizing structures. Log jams were placed in pool features and each extends approximately 20 feet along the bank and 5 to 10 feet into the channel. Over time, these structures will degrade and the bank protection function will be replaced by native woody vegetation.

Log Vane

Long vanes provide bank protection by reducing near-bank stress and redirecting flow away from the bank and into engineered log jams. These structures also dissipate energy because they typically form a scour pool on their downstream side. Log vanes are set low in the water to minimize abrupt affects on the water surface. They extend approximately 20 feet into the channel, leaving about 60 percent of the channel unobstructed for bedload transport and recreational passage.

Submerged Boulder

Submerged boulder energy dissipaters were utilized in channel construction. These structures are intended to ensure floodwaters access the floodplain at or near the design bankfull discharge and to maintain fish passage. These structures also maintain interim streambed grade control in riffle, run and glide features until natural armoring/sorting processes develop and control long-term vertical stability.

Vegetated Soil Lift

Vegetated soil lifts were installed along outer meander bends to promote the establishment of woody vegetation that will provide bank roughness, contribute to aquatic habitat, and help sustain balanced channel morphology over time. All vegetated soil lifts were constructed with cobble and wood toes to prevent scour and slumping in the short term while vegetation becomes established. Willow cuttings were installed between lifts and in some locations under the bottom lift and above the top lift where conditions appeared conducive to willow growth. In some locations, containerized plants, primarily sandbar willow (Salix exigua) and black cottonwood (Populus balsamifera) were installed behind and on top of structures.

Wrapped Coir Log

Wrapped coir logs were installed along riffle-run features primarily at the upstream and downstream ends of abandoned sections of the channel to provide temporary bank protection and retain moisture along cobble dominated channel margins while native woody vegetation with deep binding root mass develops. The coir logs were placed on narrow cobble benches that sloped away from the channel. Various plant materials were incorporated in wrapped coir log structures including stinger installed container plants (cottonwoods and willows) and willow cuttings placed both vertically and horizontally.