Transboundary Assessments of Water Quality in the Pacific Northwest

Science Center Objects

In 2019, the USGS began studying the baseline water-quality of selected transboundary rivers in the Pacific Northwest. These studies are designed to characterize current water-quality conditions so as to facilitate future assessments of potential impacts related to upstream mining activities.

Funding of transboundary water-quality assessments began with the passage of the 2018 Omnibus Spending Bill, in which Congress directed the U.S. Geological Survey to “partner with local Tribes and other Federal agencies as necessary in the area to develop a water quality strategy for transboundary rivers impacted by mining activities. Within 180 days of enactment of this Act, the USGS is directed to report back to the Committees on the necessary work needed to collect, analyze, and assess the hydrologic, water-quality, and ecological data needed to document baseline conditions and assess potential mining-related impacts.” Beginning in 2019, the USGS was allocated funds to study baseline water-quality conditions in transboundary rivers across the Pacific Northwest, including ongoing studies being conducted by USGS Science Centers in Alaska, Washington, Idaho, and Montana.

Projects selected for funding


Overview map showing state and country boundaries and transboundary project locations


Small detail map showing state boundaries and transboundary project location in Alaska

Alaska transboundary summary

Contact: Jeff Conaway

The Salmon, Unuk, Stikine, Taku, and Alsek Rivers originate in Canada and flow into Southern Alaska.  These rivers support customary and traditional, recreational, and commercial salmon fisheries. Salmon fisheries contribute an estimated $1 billion into the regional economy annually. The recently completed Northwest Transmission Line has brought power to the Southern transboundary region and accelerated mineral exploration and mine developments.  The active and proposed large-scale mining activity in the Canadian parts of these watersheds could affect the water quality and ecological condition, potentially impacting fisheries and traditional lifestyles.   Characterization of baseline conditions in transboundary rivers will be accomplished through (1) assessment of the geology and mineralization potential of study area watersheds, (2) retrospective analysis and new data collection to characterize the water, sediment, and biological quality of the Salmon, Alsek, Stikine, Taku, and Unuk Rivers, and (3) the establishment of partnerships with tribes and government agencies to ensure that assessments meet the needs of Tribes and  local stakeholders.


Small detail map showing state boundaries and transboundary project location in Washington state

Washington transboundary summary

Contacts: Robert BlackPatrick Moran

The Skagit River in Washington State represents one of the Northwest’s premier salmon fisheries and its headwaters are one of the main US strongholds of the federally listed bull trout. It produces substantial runs of all native salmon and trout species. Its headwaters in Canada drain into Ross Lake within the Ross Lake National Recreation Area / North Cascades National Park Complex. However, multiple historic, current, and planned large-scale copper mining activities in British Columbia could have measurable effects on the water quality and ecological condition of the Skagit River. While a large part of the Skagit River headwaters are within the Skagit Valley Provincial Park, part of the watershed is currently undergoing extensive logging and road building and exploratory drilling for a potential copper mine in an unprotected area. The current and rapid logging and proposed copper mine has the potential to severely impact one of the largest Chinook salmon producing rivers in the US if water quality were significantly altered.  Multiple historic, current, and planned large-scale mining activities in British Columbia also could affect the water quality and ecological condition of the Similkameen River, which hosts a critical stock of Chinook Salmon downstream of the border.  Water-quality assessments of the Skagit and Similkameen Rivers will be done using a combination of continuous water-quality monitoring, periodic water-quality sampling, and sediment and biological tissue monitoring to characterize the potential effects of mining activities on these valuable resources.


Small detail map showing state boundaries and transboundary project location in Montana and Idaho

Montana and Idaho transboundary summary

Contacts Chris MebaneChris Ellison

Coal mining in southeastern British Columbia releases selenium and other substances into the transboundary Kootenai River basin in Montana and Idaho. Work in 2018 showed that selenium concentrations in fish from the Kootenai river were elevated relative to fish in other rivers, with some fish exceeding relevant water quality criteria. The USGS Wyoming-Montana Water Science Center is collecting periodic and continuous water-quality data within and directly downstream from Lake Koocanusa to develop baseline data that describes conditions prior to the large-scale implementation of a new water-treatment method by the coal mining industry. The Idaho Water Science Center is collecting water-quality and fish tissue data to characterize the occurrence and transport of selenium and nutrients downstream from Lake Koocanusa and to evaluate pathways of contamination through the food web.