Aquatic Ecosystems and Habitats

The Issue: The Tolt River and its tributaries, including the South Fork Tolt River, have recently experienced high water temperatures above water-quality standards. Water managers can regulate flows to influence the temperature regime of the South Fork Tolt River downstream of the dam. More information is needed to determine how far downstream water temperature strategies are effective. How USGS...

The Issue: Forests in the Pacific Northwest have changed substantially over the past hundred years because of logging, changing forest management methods, and climate change. These forests contain a dense network of small headwater streams that supply cold, clean water and support 52 amphibian species. These amphibians live both in the cold streams and in the cool, moist areas nearby. Natural...

The Issue: Changes in the water temperature and flow regimes of rivers throughout the western United States have contributed to shifts in the ranges of aquatic species that they support. Cold-water species such as fish are sensitive to changes in water temperature, which regulates their physiological functions and behavior. How USGS will help: A spatial stream network (SSN) model was developed...

Pacific salmon and trout, especially coho, are threatened by a toxic contaminant resulting from tire additives that end up in untreated road runoff. This contaminant, 6PPD-q, has been associated with high rates of coho pre-spawn mortality in streams, including in the Green-Duwamish watershed. Many coho spawning streams in the watershed are predicted to be at high risk for “urban runoff mortality...

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: Stormwater runoff often carries pollutants that degrade water quality in receiving waters. A regional-scale monitoring program is necessary to objectively measure and track progress in reducing stormwater impacts on environmental health. How USGS will help: Scientists from the U.S. Geological Survey (USGS) are monitoring water quality and watershed health for urban and urbanizing areas...

The Issue: Polycyclic aromatic hydrocarbons (PAHs) are a class of oil-derived compounds widely distributed in fresh and marine waters. They pose a significant toxicity risk to fish. It can be challenging to pinpoint the source of PAHs found in wild fish populations. PAHs are widespread and come from many sources, so it is hard to determine whether fish exposure is event-related or consistent with...

The Issue: Mercury contamination and toxicity threaten Pacific lamprey recovery in the Columbia River basin. Methylmercury concentrations in larval Pacific lamprey from tributaries in the mid-Columbia were measured to be as high as 4.0 µg/g wet weight. At these concentration levels, injury is predicted to occur in more than 50% of larval and adult fish and more than 90% of early-life stage fish...

The Issue: Native American treaty rights depend on the availability of adequate and high-quality streamflow across the Western Washington, which can be degraded by water and land use, reservoir operations, and climate change among other factors. Streamflow during critical low-flow periods depend on groundwater discharge from aquifers, which also is vulnerable to human activities in the Western...

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: Streamflow permanence refers to the probability that a stream will lose surface flow (become a dry channel), as well as the timing, duration, and frequency of drying. Patterns of streamflow permanence drive important decisions regarding forest management and other land uses. The Colville National Forest Land and Resource Management Plan (2019), for example, specifies riparian management...

The Issue: The Quillayute River Basin supports habitat for migrating, spawning, and rearing steelhead and salmon. Like many salmonid-bearing watersheds in the Pacific Northwest, water temperatures in the Quillayute River Basin are expected to warm in the coming decades. Warmer water temperatures pose a risk to salmonids and other cold-water fish, with the potential to adversely impact their health...