Salt River Watershed
The Salt River watershed in western Wyoming and eastern Idaho encompasses a blue-ribbon trout fishery and its tributaries and the community of Star Valley.
Numerous issues including widespread habitat degradation, altered stream function, and water quality concerns necessitated the formation of the Salt River Watershed Group (SRWG) in 2022. The Salt River watershed includes a significant amount of federal lands – primarily National Forest lands (Bridger-Teton and Caribou-Targhee National Forests) with a small amount of Bureau of Land Management and Bureau of Reclamation lands, as well as Palisades Reservoir, a major storage reservoir of the Bureau of Reclamation’s Upper Snake River Basin. Whereas most of the tributaries and high elevation land in the watershed lie within the two national forests, the valley bottom, referred to as Star Valley, and the majority of the Salt River mainstem, are on private lands. Although agriculture dominates private land and water use, development pressure is rapidly changing this make up, as Star Valley has become one of the fastest growing areas in Wyoming. Thus, the combined challenges of 1) years of degradation of the watershed due to past land management practices, and 2) more recent and future challenges to the watershed from rapid development, make this a critical juncture for SRWG to bring diverse interests together to conserve and restore habitat and stream function while protecting water quality in the watershed.
Issues Facing the Salt River Basin
Dewatered Streams
Below the town of Smoot and above the Town of Afton, the mainstem of the Salt River is seasonally dewatered following spring runoff. This is likely a result of a combination of natural hydrologic factors, such as underlying geology that influences ground and surface water dynamics and the existence of “losing reaches,” and human impacts such as water withdrawals for irrigation, channelization and diking, and a lowered groundwater aquifer and associated water tables.
The major eastern tributaries of the Salt River in this area – Cottonwood, Dry, and Swift Creeks – are completely allocated for irrigation water, which is delivered through relatively efficient (although aging) pipe infrastructure by the irrigation districts on these systems. They are therefore seasonally dewatered every year downstream of the respective pipelines’ points of diversion. The major western tributaries in this area, Crow Creek and Stump Creek, are also fully dewatered during some drought years. Prior to human settlement, these tributaries would have naturally flooded during spring runoff, recharging the groundwater table. As agriculture developed, these tributaries were channelized and diked in the valley floor to prevent uncontrolled flooding. However, flood irrigation was popular at this time, so flooding still occurred anthropogenically. In the 1970s, most irrigators converted to sprinklers to increase efficiency. This has led to a scenario with little natural or anthropogenic flooding, combined with dry streambeds through the entire irrigation season.
As a result, the upper Salt River watershed below Smoot and above Afton likely has a lowered water table and aquifer and remains dry for most of the year, and there is no viable fisheries habitat in this more than 10-mile section of the Salt River. Ranchers around Afton have noted reduced spring creek flows and loss of wet areas on their land where “sub-water” would return to the surface from spring flooding or flood irrigation. In addition, the channelization and diking in this section has led to extreme bank and channel instability and erosion, with effects including localized flooding and land loss, and further instability and sedimentation observed downstream within the blue-ribbon trout fishery downstream of Afton.
A channelized riprapped reach of the seasonally dry section of mainstem Salt River des not allow for floodplain access and results in sediment deposition downstream.
Development
Development in the riparian area can exacerbate issues of instability and increase the associated risk.
Star Valley is the one of the fastest growing areas in Wyoming. Growth has been attributed to being an attractive area for retirees and those relocating from other parts of the country, as well as a booming bedroom community of workers that commute to the resort community of Jackson Hole, Wyoming. The Salt River is a recreational amenity that has seen increased development within the floodplain and riparian corridor and will continue to see this development pressure. As new subdivisions and homes are built within the floodplain, particularly if they are built close to the river’s banks and involve clearing of riparian vegetation, they are likely to necessitate future flood protection and bank stabilization measures like diking and riprap that impair stream function and watershed resiliency.
Water Quality
A 7.5-mile section of the Salt River downstream of Tincup Creek and the section of Stump Creek from the Idaho border to the Salt River confluence have a current Wyoming DEQ impaired listing for E. coli. This common bacterium is found in the digestive tract of mammals and is often present, along with other pathogens, in waterways in rural and agricultural areas due to the higher prevalence of septic systems and livestock manure. E. coli, ingested through recreational activities like swimming and fishing, can cause gastrointestinal distress as well as fever in humans and its presence is a useful indicator of overall water quality, including the presence of other harmful bacteria. The Salt River also has concerns about levels of sediment, temperature, and nutrients in its streams, with several major Salt River tributaries originating in Idaho and flowing into the Salt River in Wyoming identified as impaired for sediment by Idaho
Grazing is one of the several known contributors of E. coli into the Salt River watershed
Aquatic and Riparian Habitat Degradation and Loss of Stream Function
The Wyoming Game and Fish Department’s (WGFD) Statewide Habitat Plan considers the Salt River corridor to be a “restoration habitat area,” meaning it is an “important aquatic and/or terrestrial wildlife habitat that can and should be actively restored to achieve greater wildlife value.” It considers the Salt River to be a blue-ribbon trout stream fishery and a stronghold for native Snake River cutthroat trout in the 48-mile stretch downstream from the town of Afton to Palisades Reservoir.
Josh Duplechian /Trout Unlimited
The mainstem Salt River is degraded from historic channel modifications and land use practices, along with ongoing development and agricultural activities. Throughout the watershed, willows and riparian vegetation were removed from the Salt River and tributaries with the intention of making way for hay production, increasing pasture area, and reducing willow water consumption. Landowners have recounted being paid by the Soil Conservation Service (NRCS’s predecessor) to remove willows in the 1950s. This removal of riparian vegetation, combined with hay harvest and grazing up to the river’s edge, has contributed to much of the habitat degradation seen in the Salt River. Throughout the watershed, this has resulted in erosive banks and an over-widened, shallow channel with high sediment loads and little vertical cover from overhanging willows and woody debris. High sediment loads reduce macroinvertebrate productivity and spawning habitat availability and success. Lack of depth and vegetative cover dramatically reduces availability of trout habitat.
Some sections of the Salt River and lower elevation reaches of tributaries have been straightened and diked with the intention of reducing flood risk, conveying high flows, and increasing area available for agriculture. These reaches have impaired trout habitat and greatly reduced floodplain connectivity, which are in turn related to the loss of riparian function and water availability issues.
Over widened shallow channel lacking riparian vegetation in a public fishing easement in the Salt River. This is indicative of habitat and gracing issues throughout the watershed.
Some sections of the Salt River and lower elevation reaches of tributaries have been straightened and diked with the intention of reducing flood risk, conveying high flows, and increasing area available for agriculture. These reaches have impaired trout habitat and greatly reduced floodplain connectivity, which are in turn related to the loss of riparian function and water availability issues.
The latest Statewide Habitat Plan can be found here .
PROJECTS
1. Lower Swift Creek Stream Restoration and Stabilization Project
Lower Swift Creek suffered from extreme bank instability and erosion due to historic willow removal, water withdrawal, and upstream channel manipulations. A partnership of Trout Unlimited (TU), Star Valley Conservation District (SVCD), USDA-Natural Resources Conservation Service (NRCS), Wyoming Game and Fish Department (WGFD), and U.S. Fish and Wildlife Service Partners for Fish and Wildlife Program worked to address these issues. The project sought to protect and improve spawning cutthroat trout habitat in lower Swift Creek, reduce sediment contributions to the Salt River, and reduce landowner flood risk and maintenance requirements. Before the project, this one-mile stretch of Swift Creek was estimated to be contributing 250 dump trucks of sediment into the Salt River each year.
Severe bank and channel instability and pasture loss on lower Swift Creek prior to restoration
Stable banks with toewood and willow growth after restoration
For more information visit The Salt River Watershed Group .
2. Tincup Creek Stream Restoration Project
The Tincup Creek Stream Restoration Project worked to improve riparian conditions and habitat for Yellowstone cutthroat trout, northern leatherside chub, boreal toad, western pearl shell mussels and bluehead suckers. These are all native species with special management emphasis. Because of the assemblage of these native species, and the degraded yet recoverable nature of this system, Trout Unlimited (TU) and the Caribou-Targhee National Forest (CTNF) chose to focus their efforts here.
The primary cause for the degraded state of the stream was linked to aerial spraying of willows in 1956, which precipitated the subsequent unraveling of the stream system. Five miles of stream habitat were restored in the work along Tincup Road. Phase 1 of the project was completed in 2017, Phase 2 and 3A were completed in 2019, and Phase 3B was completed in 2020.
Stream restoration focused on elevating and narrowing the stream channel to reconnect it to the floodplain, and activating historic meanders to increase channel length and reduce erosive force. Raising the streambed elevation and narrowing the channel has spread flood flows and raised the water table across the full valley floor. Visible results of this include a dramatic increase in vegetative productivity and diverse flow paths on the floodplain.
Imagery from September 2021 demonstrating the dry, abandoned floodplain due to an over widened entrenched channel.
Imagery from September 2023 shows the green, well-connected floodplain of the restored creek with healthy stream length and channel dimensions.
For more information visit The Salt River Watershed Group .
3. Rico Diversion Fish Passage and Stabilization Project
Landowners adjacent to the diversion for the New Rico Ditch contacted Trout Unlimited, WGFD, and other agencies due to extreme erosion and instability concerns in 2022. During runoff in 2023, banks eroded as much as 50 feet. The bank nearest the New Rico Ditch was migrating up to six feet per day, with only ten feet remaining between the river and the ditch on June 1 when emergency riprap was placed. The instability was due to a lack of willows and other woody riparian vegetation to hold banks together. Due to the severity of erosion, the project was expedited to complete construction before the next runoff event. The design was completed by WWC Engineering. Toewood, bankfull benches, and willow transplants are among the bioengineering approaches that were used to stabilize and vegetate outside banks, while also adding habitat value. The design also incorporated natural channel dimensions and a stable diversion structure to ensure sediment was transported through the project reach. The irrigator had previously constructed a rubble dam each year, resulting in further channel instability.
Before restoration, banks were vertical and eroding with limited riparian vegetation.
After project completion, banks contained large rootwads pushing the force of the river off the bank, whole willow transplants, and floodplain benches with willow staking and riparian plantings. These banks will provide long-term stability and high quality trout habitat.
Prior to project completion, the rubble dam diversion was constructed of concrete, rocks, tarps and debris and required frequent repairs.
The new diversion is located further upstream where an armored riffle sets the water level and allows the irrigator to control flows with headgate adjustments.
For more information visit The Salt River Watershed Group .
4. North Fork Tincup Creek Process Based Restoration Project
The first phase of work on the North Fork of Tincup Creek took place in 2022 with the second phase slated for summer of 2024. This project has similar objectives to the downstream Tincup Creek Restoration Project but required a novel approach due to its location in a roadless area. Heavy machinery could not access the project, so project partners chose to implement Process Based Restoration using draft horse teams to pull logs into the creek. Conservation Corps teams pound wooden posts to secure the log structures and increase longevity. These log structures are designed to aggrade the streambed and reconnect the stream to its floodplain. They also improve habitat complexity and quality for cutthroat trout.
5. Salt River Clarks Barn Fish Passage and Restoration Project
The Clarks Barn Fishing Access Easement is an extensive, valuable wade-fishing access area for the Star Valley Community. Historically, it was known for incredible macroinvertebrate hatches and high spawning utilization. Due to historic willow removal, bank erosion has led to a severely over-widened, shallow channel with high sediment loads and poor habitat quality. This project will take place on the upper 0.9 miles of the access easement and will focus on stabilizing banks, restoring healthy channel dimensions, establishing riparian vegetation, and increasing the quantity and quality of trout habitat. After the project, the channel will be narrower with deeper pools and clean gravels with much greater macroinvertebrate and trout productivity, as well as improved spawning habitat. These changes will result in cooler summer water temperatures and higher trout numbers throughout the project area.
The project will also include replacement of the diversion and headgate for the Herber No. 5 Ditch. The existing diversion requires the placement of logs and planks in drought years to meet irrigator’s water needs. This creates unnecessary work for irrigators, as well as a fish passage and sediment transport barrier that can exacerbate instability in the reach. This diversion will be replaced with a stable, engineered structure that provides year-round fish passage and sediment transport while also allowing irrigators to manage their water with headgate adjustments.
Typical bank in the project reach – eroding, vertical bank with pasture grass up to the river’s edge.
The existing diversion requires irrigators to place logs, planks, and tarps across the river during drought years.
6. Salt River Narrows Meander Activation and Restoration Project
The Narrows is a constriction in Star Valley between the Upper Valley and Lower Valley. It is generally higher gradient with greater velocities and less sinuosity than other reaches of the Salt River. However, within this project reach there is a broad, low-gradient valley bottom that historically held a river with sweeping meanders and higher stream length. Channel modifications, lost riparian vegetation, and other historic land use resulted in meander avulsions and lost stream length. The existing stream from the Diversion Access upstream to the Highway 89 bridge is over-steepened with swift pools and poor habitat complexity for trout. The steep grade results in high stream energies that have caused severe bank erosion in a few locations, causing concern for landowners. This project will restore the river to a healthy stream length with far greater pool habitat and habitat complexity for trout. These actions will produce a better fishery for the Star Valley community, while also helping to reduce downstream flood risk and sediment loads.
High stream power has caused severe bank erosion in some areas of the project reach.
