Hydrologic Hazards

The Issue: Glaciers in the Hoh River watershed are expected to largely disappear by 2050, while flooding is expected to become more intense. Understanding if or how this will impact sediment transport and channel change in the watershed is relevant for salmon habitat, restoration efforts, and flood hazard management. However, there is relatively little information about historical channel...

The Issue: Changes in channel geometry in the Nooksack River can reduce flood conveyance capacity, and so increase local flood hazards. Near Everson, WA, sand and gravel accumulations have increased the likelihood that major floods will spill overbank, sending water north over a low drainage divide where it may cause substantial damage to communities in both Washington and British Columbia. Major...

The Issue: Ice jams can occur at the outlet of Osoyoos Lake on the border of Canada and the United States, resulting in a decrease or complete interruption in streamflow on the Okanogan River. These ice jams appear to be occurring at a greater frequency than they have in the past and interruptions in streamflow can hinder the passage of anadromous fish and impact downstream water rights and water...

The Issue: Scientists and water-resource managers recognize the increasing impact of wildfires on water supply in the western U.S. The increasing frequency and severity of wildfires are linked to changes in snowpack, warmer temperatures, and drought. Sedimentation following wildfire can impact aquatic habitat, reservoir storage capacity, water quality, and thus public drinking water supplies...

The Issue: Most of the Duwamish River valley in Seattle, Washington, is less than 20 feet above sea level; consequently, the river valley is prone to flooding during high tides, extreme rainfall, and high streamflow. In addition, groundwater inundation—localized coastal flooding due to a rise of the groundwater table with global sea-level rise—may compound flooding issues in the area. The King...

Wildfires can negatively impact reservoirs and water supply. In 2021, a wildfire in Okanagan County, Washington, engulfed a large area around Conconully Reservoir. USGS scientists are assessing sediment and water quality in the reservoir and surrounding streams.

The issue: National interests in water information are important but challenging to incorporate into planning and operation of a monitoring network driven by local information needs. These interests include an understanding of the spatial variability in water availability across the United States, anthro-physical factors including climate and land use that affect water availability, and federal...

The issue: In the summer of 2020, the Pilchuck Dam will be removed, allowing salmon access to the upper third of the Pilchuck River watershed for the first time in over a century. This removal will be associated with a short period increased sediment delivery, as the river re-works material trapped behind the dam. While the volume of impounded sediment is small and major changes in the downstream...

In the immediate aftermath of the SR530 Landslide, the USGS supported first responders and decision-makers as a key member of the collaborative effort to monitor the stability of the landslide deposit and the associated impoundment of the North Fork Stillaguamish River during rescue operations. With the initial disaster response now over, longer-term questions have arisen regarding the stability...

The Issue: Large, in-channel wood that helps to create and maintain healthy aquatic habitat in rivers throughout the Pacific Northwest was removed from many rivers in the past. In 2009, King County put wood back into the river to restore the Raging River watershed. To guide the county's restoration of the Raging River watershed, managers need to know the effect of restoration actions on in-stream...

The Issue: Since 1952 water diverted from the Columbia River has been used to irrigate parts of the Pasco basin in eastern Washington. As a result of the surface-water irrigation, groundwater levels generally have risen in the area. The increases in groundwater fluxes and groundwater in storage have created a need to better understand the flow system before and after the start of irrigation to...

The Issue: Significant flooding occurred throughout western Washington on January 7 and 8, 2009. As part of its Hazard Mitigation effort, the Federal Emergency Management Agency (FEMA) Region X needs documentation on the extent of flooding for verifying Preliminary Digital Flood Insurance Rate Maps (DFIRMs) and corresponding Flood Insurance Studies (FIS) that have been recently completed, or are...