The Habitat Restoration Story
The degradation of inland salmonid habitats had been ongoing for >160 years when salmonid populations began to be listed under the Endangered Species Act in the 1990s. Intensive habitat restoration has been underway since the enactment of the State of Washington’s Salmon Recovery Act of 1998 in the Snake River Region; though some early actions were implemented quickly following the ESA listing of several local populations. The early actions focused on removal of fish passage barriers, screening irrigation diversions, reducing fine sediments from entering spawning and rearing areas and restoring riparian habitats. With the completion of the 2005 Snake River Salmon Recovery Plan for SE Washington, habitat factors limiting each population were identified leading restoration objectives. In the 2005 restoration plan, habitat factors most limiting salmonid populations regionally included; barriers, unscreened diversions, low/dewatered streams, high stream temperature, lack of stream channel complexity, fine sediments, absent or degraded riparian cover and stream channel confinement.
Since initiation of restoration implementation, great strides have been made in removing fish passage barriers, unscreened irrigation diversions, minimizing fine sediments and planting riparian buffers (Table 1). The removal of barriers has opened > 229 miles of habitat and improved access to even more, and the placement of screens has reduced mortality on juvenile salmonids. The conversion from conventional agricultural tillage practices to ones which minimize tillage and increase ground cover have greatly reduce the loss of soil from uplands, improving spawning and rearing habitat. The planting of hundreds of miles of riparian buffers has had a synergistic effect of further reducing fine sediment, shading the stream channel reducing temperature and providing large wood debris increasing channel complexity.
Table 1: Habitat restoration metric completed by the project sponsors between 1999 and 2012 in the Snake River Salmon Recovery Region.
Limiting Factor Addressed
Unit of Measure
|Fish Passage Barriers Removed or Modified||
|Irrigation Diversions Properly Screened||
|In-stream Flow Increased Through Efficiency and Leases||
|Channel Complexity (Meeting 1 key piece per bank width)||
|Upland Agriculture Best Management Practices Reduce Erosion||
|Riparian Habitat Restored||
|Stream Channel Confinement Reduced||
Visual Examples of Degraded or Poor Habitat Condition Restored to Desired Condition
The following section will provide illustrations of past conditions which were detrimental to salmonids and the current desired condition post restoration. The examples have been selected from the region. An example has been provided for fish passage, irrigation diversion screens, fine sediment upland best management pratices and riparian planting.
Fish Passage (52 Barriers Removed)
Figure 1: The Hofer irrigation diversion on the lower Touchet River prior to 2005 (above left) was a passage barrier to migrating adult steelhead in the late summer and into the fall and to spring Chinook in the late spring. Through the coordination of the Walla Walla County Conservation District and the Confederated Tribes of the Umatilla Indian Reservation the diversion point was reconstructed with fish passage meeting passage guidelines (above right). The immediate outcome of the project has been the arrival of summer steelhead upstream to the City of Waitsburg month earlier than observed before the project, local angles greatly appreciate the increased opportunity.
Diversion Screens (526 Diversions Screened)
Figure 2: The distributary Garrison Creek originates from Mill Creek before flowing into the City of Walla Walla where it becomes an urban waterway. The distributary has carreteristics detrimental to salmonids and it was determined untill conditions in the channel can be adressed a fish sreen be place at the diversion point. The preproject condition at the site had no screen and fish entering the channel were unable to migrate back to Mill Creek and became entrained in the urban waterway (above left). In 2010, the Walla Walla Conservation District worked with Army Corps of Engineers to construct a fish screen which would prevent mortality at the site (above right).
Upland Best Management Pratices (121,730 acres Converted)
Figure 3: Direct seed agriculture has the potential to reduce fine sediments from being washed from agricultural fields into our waterways. The photos above illustrate conditions perpetuated by conventional tillage and how direct seed reduces soil erosion. The upper two photo illustrate tilled fields and how they can suffer erosion and soil loss during precipitation events. The bottom left photo illustrates the process of direct seeding notice the straw residue on the field during planting. It is the residue and the root matrix from the old wheat that helps hold the soil in place during precipitation events reducing erosion. The lower right photo illustrates how persistent the straw residue is extending benefits to the wheat as it grows.
Riparian Habitat Restoration (262 River Miles Restored)
Figure 4: Riparian habitat benefits salmon populations by reducing fine sediments entering stream, reduce summer high temperatures through shading and provides habitat complexity by supplying large wood. The above photo illustrate a new CREP funded riparian planting on the left and that same site as it matured on the left. The benefits from riparian planting are realized over a long period of time (>50years) with the first effects are the development of a buffer strip between agricultural activities and the watercourse. Over time as trees grow they will begin to shad the stream and over decades will begin to contribute whole trees to complexity forming log jams.
Riparian Habitat and Floodplain Conectivity
Todays restoration often strives to develop dynamic river channels which utilize the floodplain and travel across the floodplain over time. In 1996 the Tucannon River had experienced a flood event of significants which severly modified the channel in many locations. The following series of images are from a location on the Tucannon River where the river eroded several channel braids creating a shallow simplefied channel which acted as a heat sink increasing water temperatures.
Figure 5: The image upper left illustrates the condition of river channel, floodplain and riparina habitat. Although the cannel was in a dynmic condition in 1998 following the 1996 flooding event, the channel was shallow and provided little in the form of habitat complexity. Additionally, riparian vegatation and soil had been scoured from the floodplain during the flood event and two years later riparian showed no signs of recovering. Due to the rapid lateral movement of the river channel through a floodplain devoid of trees it was necessary to introduce temporary stabiliity to the channel through the placment of a series of log jams (upper right). In 1999, the Washington Department of Fish and Wildlife worked with a local contractor to place the jams. Over a ten year period stability was maintained in the project site as intended maintain floodplain conectivity and establishing a riparian habitat (lower left), notice the log jan with the rock on it is the same jam shown in the upper right photo. By 2011, the high water events of 2009 and 2010 had reshaped the floodplain in the project area again creating some of the multiple channels created in 1996, however this time the presence of riparian vegatation created channels which were deep, shadded and highly complex (lower right). As the river in this reach continues toward a dynamic equlibrium we will continue to see how floodplain conectivity interacts with riparian habitat and shapes river channels.
Restoration of River Function
Habitat restoration in the Snake River Region has been undergoing a transition from site specific actions focusing on small stream reaches or addressing a localized problems to much larger stream reaches adressing ecologic and geomorphic function suported by geomorphic studies and environmental engineering design. The motivation in making this move is to set conditions in the river system so that the river can function naturally allowing the river to do the work of restoration and maintence. Examples of project which utilize the river to create habitat are the Tucannon River Levee Set back project completed in 2010 by the Columbia Conservation District, another is the Tucannon Large Wood Replenishment Project Area 10 implemented by the Washington Department of Fish and Wildlife in 2012. Both of these projects did little to the river at the time of implementation but overtime and highflow events it is anticipated and has been observed that channel complexity and floodplain conectivity have begun to increase. In 2oo9 and again in 2010 the WDFW, the UFFS and CTUIR collaborated in a large wood replenishment project which capitalized on fire killed trees along the upper Tucannon on the wildlife area by felling hazard trees into the river. The purpose of the project was to increase complexity by providing the river materials (Figure 6). In total about 100 trees were fell into the river forming a number of side channels, pools and jams. (Click on Log Jam Examples to see more photos from the wood replenishment project)
Figure 6: Greater than 80% of the Tucannon River by length is deficient in large wood debris as outline in the Salmon Recovery Plan for South Eastern Washington (Tucannon River Geomorphic Assessment 2011). The Tucannon River large wood replenishment project aimed to increase LWD materials available to the river and let the river place them and modify habitat. The illustration above shows two rows of images taken in 2006 (pre-project), 2009, and 2010 with the upper row showing the photo point over time and the bottom row aerial images from the same time frame. The project at this site consisted of felling approximately 25 trees in the stream channel and on the floodplain and resulted in the development of numerous logjams and gravel deposition. The stream channel was previously incised and single channel pre-project and following treatment and two subsequent high flows, incision was reduced the channel was connected to the floodplain, complexity increased dramatically and side channel and off channel habitat was increased.