Sediment load and distribution in the lower Skagit River, Skagit County, Washington

Curran, Christopher A.; Grossman, Eric E.; Mastin, Mark C.; Huffman, Raegan L.

doi:10.3133/sir20165106

Cited by 10 publications

(16 citation statements)

References 8 publications

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“…The beds are larger off the South Fork than off the North Fork (Figure 1). Further, water and sediment discharges are usually lower in the South Fork than in the North Fork (Curran et al 2016), and distance between the river fork outlet and eelgrass is greater off the South Fork than off the North Fork ( Figure 1). Eelgrass between the North and South forks and offshore from diked-off farmland forms a single large continuous bed, and eelgrass north of the jetty also forms a relatively continuous bed ( Figure 1).…”

Section: Methodsmentioning

confidence: 99%

Juvenile Chinook Salmon and Forage Fish Use of Eelgrass Habitats in a Diked and Channelized Puget Sound River Delta

2018

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Eelgrass Zostera marina can form extensive meadows on Puget Sound river deltas. The extent to which these meadows provide critical rearing habitat for local estuarine fishes, especially out-migrating juvenile salmon, is not well understood. Further, delta eelgrass has been impacted by diking and river channelization with unknown consequences for fish. We sampled fish in the Skagit River delta, Washington, during April-September with a lampara net, which is well suited to capturing fish in eelgrass. We compared abundance and body size of Chinook Salmon Oncorhynchus tshawytscha and three forage fish species between eelgrass and nearby unvegetated habitat. We also assessed combined effects of eelgrass characteristics (meadow size and morphology) and oceanographic conditions (temperature and salinity), which covaried according to proximity and orientation to channelized distributary outlets, diked shorelines, and a jetty. Chinook Salmon were more abundant in eelgrass than in unvegetated habitat in June-July and were relatively more abundant in eelgrass compared with unvegetated habitat in regions with intact eelgrass than offshore from a channelized distributary outlet. Abundances of Pacific Herring Clupea pallasii and Shiner Perch Cymatogaster aggregata were consistently severalfold higher in eelgrass than in unvegetated habitat. Surf Smelt Hypomesus pretiosus were more abundant in eelgrass than in unvegetated habitat at some locations, but never less abundant in eelgrass. Our results suggest that conservation and restoration of delta eelgrass would benefit these species and help to identify the settings in which these actions would be most beneficial.

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Section: Methodsmentioning

confidence: 99%

Juvenile Chinook Salmon and Forage Fish Use of Eelgrass Habitats in a Diked and Channelized Puget Sound River Delta

2018

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“…As part of this study, a sediment trap was established near the mouth of Skagit River. This well-known depositional area recorded a bed elevation change of 8 In addition to the sediment load, the USGS study by Curran et al [15] also provided grain size distribution information based on analysis of water column grab samples also collected at Mt. Vernon gage.…”

Section: Sediment Transport Model Of the Skagit River Estuary With Thmentioning

confidence: 99%

“…Vernon estimated using the above regressions is also presented in Figure 4 for the period 1988 to 2010. In addition to the sediment load, the USGS study by Curran et al [15] also provided grain size distribution information based on analysis of water column grab samples also collected at Mt. Vernon gage.…”

Section: Sediment Transport Model Of the Skagit River Estuary With Thmentioning

confidence: 99%

“…Using a combination of total suspended solids (TSS) grabs and turbidity measurements for fine sediment (i.e., silt-and clay-sized particles smaller than 0.0625 mm) and fine-to medium-sized sand (0.0625-0.5 mm), USGS developed a suspended sediment-rating curve for the Mt. Vernon site by Curran et al [15] as follows: …”

Section: Hydrodynamic Model Of the Skagit River Estuary With The Swinmentioning

confidence: 99%

“…Table 3 below provides a listing of the sediment model parameters used in this application. SSC at the river boundary was specified using a modified version of the USGS rating curve from Curran et al [15] of the form…”

Section: Sediment Transport Model Of the Skagit River Estuary With Thmentioning

confidence: 99%

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Sediment Transport into the Swinomish Navigation Channel, Puget Sound—Habitat Restoration versus Navigation Maintenance Needs

Khangaonkar

Nugraha

Hinton

et al. 2017

JMSE

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Abstract:The 11 mile (1.6 km) Swinomish Federal Navigation Channel provides a safe and short passage to fishing and recreational craft in and out of Northern Puget Sound by connecting Skagit and Padilla Bays, US State abbrev., USA. A network of dikes and jetties were constructed through the Swinomish corridor between 1893 and 1936 to improve navigation functionality. Over the years, these river training dikes and jetties designed to minimize sedimentation in the channel have deteriorated, resulting in reduced protection of the channel. The need to repair or modify dikes/jetties for channel maintenance, however, may conflict with salmon habitat restoration goals aimed at improving access, connectivity and brackish water habitat. Several restoration projects have been proposed in the Skagit delta involving breaching, lowering, or removal of dikes. To assess relative merits of the available alternatives, a hydrodynamic model of the Skagit River estuary was developed using the Finite Volume Community Ocean Model (FVCOM). In this paper, we present the refinement and calibration of the model using oceanographic data collected from the years 2006 and 2009 with a focus on the sediment and brackish water transport from the river and Skagit Bay tide flats to the Swinomish Channel. The model was applied to assess the feasibility of achieving the desired dual outcome of (a) reducing sedimentation and shoaling in the Swinomish Channel and (b) providing a direct migration pathway and improved conveyance of freshwater into the Swinomish Channel. The potential reduction in shoaling through site-specific structure repairs is evaluated. Similarly, the potential to significantly improve of brackish water habitat through dike breach restoration actions using the McGlinn Causeway project example, along with its impacts on sediment deposition in the Swinomish Navigation Channel, is examined.

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Changes in suspended‐sediment yields under divergent land‐cover disturbance histories: A comparison of two large watersheds, Olympic Mountains, USA

Jaeger

Anderson

Dunn

2023

Earth Surf Processes Landf

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Improvements in timber harvest practices and reductions in harvest volumes over the past half century are commonly presumed to have reduced sediment loads in many western US rivers. However, direct assessments in larger watersheds are relatively sparse. Here, we compare 2019-21 sediment concentrations against those of the late 1970s in the Bogachiel and Calawah River watersheds, adjacent and similarly sized ($300 km 2 ) basins in the western Olympic Mountains of Washington State. The Calawah River watershed has experienced significant land-cover disturbance, including a large 1951 fire, extensive post-fire salvage logging, and relatively high rates of timber harvest through the 1990s. In contrast, the Bogachiel River watershed did not burn, and experienced only modest timber harvest that largely post-dated 1970s sediment monitoring. Channel-width trends suggest the Calawah River was still recovering from 1950s disturbances in the late 1970s. We found that 2019-21 suspended-sediment loads in the Calawah River were 2.3-2.6 times lower than would have been expected based on 1970s sediment rating curves, while recent loads in the Bogachiel River were a factor of 1.4 ± 1.0 lower. We consider the plausibility and possible explanations of declining concentrations in the less-disturbed Bogachiel River. Suspended-sediment yields in the Bogachiel River were two times higher than yields in the Calawah River, which is attributed to a combination of modestly higher precipitation, more efficient runoff generation, and more extensive and erodible Quaternary valley fills in the Bogachiel River. Regional shifts in flood hydrology have also influenced suspended-sediment loads in both watersheds. Our results then document a significant decline in suspended-sediment concentrations in the Calawah River over the past half century. Reduced land-cover disturbance provides the simplest and most likely explanation for this decline, though the wide range of possible concentration changes in the Bogachiel River leaves open possibilities that other processes (human, natural, or methodologic) could be a factor.

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Sediment load and distribution in the lower Skagit River, Skagit County, Washington

Cited by 10 publications

References 8 publications

Juvenile Chinook Salmon and Forage Fish Use of Eelgrass Habitats in a Diked and Channelized Puget Sound River Delta

Juvenile Chinook Salmon and Forage Fish Use of Eelgrass Habitats in a Diked and Channelized Puget Sound River Delta

Sediment Transport into the Swinomish Navigation Channel, Puget Sound—Habitat Restoration versus Navigation Maintenance Needs

Changes in suspended‐sediment yields under divergent land‐cover disturbance histories: A comparison of two large watersheds, Olympic Mountains, USA

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