Geology topics

Research about North Fork Toutle River

Source-linked reports with geographic coverage including North Fork Toutle River.

4 recordsLinked to original sources

USGS2019

Toutle River debris flows initiated by atmospheric rivers: November 2006

In early November, 2006, an atmospheric river brought heavy rainfall and high freezing levels to the Pacific Northwest. Without snowpack to buffer the hydrologic response, the storm caused widespread landslides and debris flows in drainages sourced from every central Cascades volcano. At Mount St. Helens, in southwestern Washington State, intense rainfall in the crater of the volcano caused at least two mass failures with an aggregate volume of 4.5 million m3, which spawned a series of debris flows with velocities as great as 11 m/s. The debris flows incised Loowit Creek as much as 9 m and traveled 16 river km before transforming to hyperconcentrated flow via rapid dilution at the confluence of North Fork Toutle River (NFT), Castle Creek, and Maratta Creek (Figure 1). Reduced channel gradient downstream lowered velocity enough to transform to sediment-laden streamflow less than 40 km from the source, where suspended-sediment concentration (SSC) peaked at 177,000 mg/L. Heavy rain persisted for several days, producing over 100 cm of rainfall in upper NFT basin which caused immediate remobilization of surface deposits; half of the annual suspended-sediment discharge (SSQ) for water year (WY) 2007 was transported in 5 days, despite a relatively low 7-year flood recurrence interval. This analysis expands upon Major et al. (2005), Pitlick et al. (2007), and Olsen (2011) to document the largest suite of rainfall-triggered debris flows identified to date at Mount St. Helens. We investigate debris flow initiation, velocity, deposition, and downstream sediment flux in the NFT basin by integrating data from near real-time monitoring stations, remote sensing, terrestrial surveying, and fluvial sediment samples.

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USGS2015

Evaluating turbidity and suspended-sediment concentration relations from the North Fork Toutle River basin near Mount St. Helens, Washington; annual, seasonal, event, and particle size variations - a preliminary analysis.

Regression of in-stream turbidity with concurrent sample-based suspended-sediment concentration (SSC) has become an accepted method for producing unit-value time series of inferred SSC (Rasmussen et al., 2009). Turbidity-SSC regression models are increasingly used to generate suspended-sediment records for Pacific Northwest rivers (e.g., Curran et al., 2014; Schenk and Bragg, 2014; Uhrich and Bragg, 2003). Recent work developing turbidity-SSC models for the North Fork Toutle River in Southwest Washington (Uhrich et al., 2014), as well as other studies (Landers and Sturm, 2013, Merten et al., 2014), suggests that models derived from annual or greater datasets may not adequately reflect shorter term changes in turbidity-SSC relations, warranting closer inspection of such relations. In-stream turbidity measurements and suspended-sediment samples have been collected from the North Fork Toutle River since 2010. The study site, U.S. Geological Survey (USGS) streamgage 14240525 near Kid Valley, Washington, is 13 river km downstream of the debris avalanche emplaced by the 1980 eruption of Mount St. Helens (Lipman and Mullineaux, 1981), and 2 river km downstream of the large sediment retention structure (SRS) built from 1987–1989 to mitigate the associated sediment hazard. The debris avalanche extends roughly 25 km down valley from the edifice of the volcano and is the primary source of suspended sediment moving past the streamgage (NF Toutle-SRS). Other significant sources are debris flow events and sand deposits upstream of the SRS, which are periodically remobilized and transported downstream. Also, finer material often is derived from the clay-rich original debris avalanche deposit, while coarser material can derive from areas such as fluvially reworked terraces.

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USGS2013

Evaluation of the behavior and movement patterns of adult coho salmon and steelhead in the North Fork Toutle River, Washington, 2005-2009

The 1980 eruption of Mount St. Helens severely affected the North Fork Toutle River (hereafter Toutle River), Washington, and threatened anadromous salmon (Oncorhynchus spp.) populations in the basin. The Toutle River was further affected in 1989 when a sediment retention structure (SRS) was constructed to trap sediments in the upper basin. The SRS completely blocked upstream volitional passage, so a fish collection facility (FCF) was constructed to trap adult coho salmon (O. kisutch) and steelhead (O. mykiss) so they could be transported upstream of the SRS. The Washington Department of Fish and Wildlife (WDFW) has operated a trap-and-haul program since 1989 to transport coho salmon and steelhead into tributaries of the Toutle River, upstream of the SRS. Although this program has allowed wild coho salmon and steelhead populations to persist in the Toutle River basin, the trap-andhaul program has faced many challenges that may be limiting the effectiveness of the program. We conducted a multi-year evaluation during 2005–2009 to monitor tagged fish in the upper Toutle River to provide information on the movements and behavior of adult coho salmon and steelhead, and to evaluate the efficacy of the FCF. Radio-tagged coho salmon and steelhead were released: (1) in Toutle River tributaries to evaluate the behavior and movements of fish released as part of the trap-and-haul program; (2) between the FCF and SRS to determine if volitional upstream passage through the SRS spillway was possible; (3) in the sediment plain upstream of the SRS to determine if volitional passage through the sediment plain was possible; and (4) downstream of the FCF to evaluate the efficacy of the structure. We also deployed an acoustic camera in the FCF to monitor fish movements near the entrance to the FCF, and in the fish holding vault where coho salmon and steelhead are trapped. A total of 20 radio-tagged coho salmon and 10 radio-tagged steelhead were released into Alder and Hoffstadt Creeks, the locations where trap-and-haul fish were released during 2005–2006. None of the tagged fish left the tributaries where they were released, but four radio tags were detected near the release sites, and it was not possible to determine if this was because the transmitters were regurgitated, or if some of the tagged fish had died. The results from this portion of the study indicated that trap-and-haul fish remain in the tributaries where they can spawn, but the trap-and-haul process is labor-intensive, and handling stress and mortality could occur. Tagged-fish releases upstream of the FCF showed that the SRS spillway was a complete migration barrier for all coho salmon and most steelhead. We released a total of 20 radio-tagged coho salmon and 23 radio-tagged steelhead during 2005–2007. No tagged coho salmon passed upstream through the SRS spillway, whereas 13 percent of the radio-tagged steelhead did migrate upstream through the structure. Radio-tagged coho salmon and steelhead that did not pass upstream remained in the FCF–SRS reach for an average of 7.5 and 16.1 d, respectively, before moving downstream. These data show that trap-and-haul releases of fish immediately upstream of the FCF would not be beneficial to coho salmon and steelhead populations in the system. Releasing tagged fish into the sediment plain was only moderately successful for coho salmon, but a large percentage of tagged steelhead moved upstream through the sediment plain to areas where spawning could presumably occur. During 2005–2009, we released 47 tagged coho salmon and 65 tagged steelhead into the sediment plain. Only 28 percent of the coho salmon were later detected upstream of the sediment plain, and the highest percentage of the release group (62 percent) never left the sediment plain. However, 69 percent of the steelhead moved upstream through the sediment plain and entered Toutle River tributaries or remained in the mainstem Toutle River where spawning could presumably occur. Adult steelhead can survive freshwater spawning, outmigrate to the ocean, and then return to spawn in successive years; 12 percent of the tagged steelhead successfully moved downstream of the FCF after the spawning period, and 5 percent of the tagged steelhead returned to the FCF a year after they were originally tagged. Evaluations at the FCF showed that the structure was not efficient at collecting adult salmon. During 2008–2009, 9 radio-tagged coho salmon and 11 radio-tagged steelhead were released to observe behavior near the facility and to estimate the recapture rate in the FCF. None of the tagged coho salmon were recaptured and only 27 percent of the tagged steelhead were recaptured. Additionally, we observed fish behavior at the FCF with an acoustic camera and found that relatively large numbers (>100 fish/sampling period) of adult salmon entered the FCF but similar numbers of fish exited during these periods as well. This suggested that the efficacy of the FCF was low. Our study was limited by the number of fish that could be handled each year and the number of transmitters that could be purchased annually, but our evaluations provided the first empirical data on adult salmon behavior and movement patterns in the Toutle River since the 1980 eruption of Mount St. Helens. Since the completion of this work, the U.S. Army Corps of Engineers has altered the SRS spillway and sediment plain; however, our results do provide information to assist fishery managers tasked with the complex management of wild salmon populations in the Toutle River. Future evaluations of juvenile and adult salmon behavior and movement likely will be required to effectively manage these populations in this complex system.

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USGS2010

Flow resistance under conditions of intense gravel transport

A study of flow resistance was undertaken in a channelized reach of the North Fork Toutle River, downstream of Mount St. Helens, Washington. Hydraulic and sediment transport data were collected in flows with velocities up to 3 m/s and shear stresses up to 7 times the critical value needed for bed load transport. Details of the flow structure as revealed in vertical velocity profiles indicate that weak bed load transport over a plane gravel bed has little effect on flow resistance. The plane gravel bed persists up to stresses ∼3 times critical, at which point, irregular bed forms appear. Bed forms greatly increase flow resistance and cause velocity profiles to become distorted. The latter arises as an effect of flows becoming depth-limited as bed form amplitude increases. At very high rates of bed load transport, an upper stage plane bed appeared. Velocity profiles measured in these flows match the law of the wall closely, with the equivalent roughness being well represented by k s = 3 D 84 of the bed load. The effects noted here will be important in very large floods or in rivers that are not free to widen, such as those cut into bedrock.

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