Transboundary Watersheds

Rivers know no borders. They flow freely across landscapes, obeying only the laws of physics. Rivers sustain both human and natural systems. They provide drinking water, serve as a source of irrigation, and supply sediment that sustains soils. They function as conduits for people and goods, their flow generates electrical power, and the force of their floods can reshape landscapes. Rivers are home to many, including aquatic species and human communities living along their banks. Understanding river systems is crucial for supporting and sustaining their critical functions.

Water Quality Overview

Water quality is one way to understand the health of rivers. Generally, water quality can be thought of as a measure of the suitability of water for a particular use. Scientists study the chemical properties of water because conditions like pH and dissolved oxygen dictate which organisms will thrive. Understanding what is in water can enable predictions of how it will respond in different conditions. This can help managers decide what actions to take or to avoid, promoting the health of the people and ecosystems dependent on rivers.

U.S. Geological Survey scientists perform a range of water quality monitoring tasks in the field and the lab.

The quality of water flowing through a river may be highly variable with space and time. Water quality depends on complex relationships between processes in the watershed. A watershed is all the area of land that drains streams and rainfall to a common outlet such as the ocean, a confluence of rivers, or any point along the stream channel. Physical processes – both human and natural – can influence the quality of water moving through any given watershed. Factors may include the amount, timing, and form of precipitation; terrain; plant and animal communities; and human activities.

A river may have seasonally higher concentrations of sediments corresponding with precipitation increasing the amount of water transported by the river, and thus its power to carry particles. Continuous monitoring of key parameters (measures) such as temperature, pH, and dissolved oxygen allow scientists to understand the critical conditions under which chemical reactions occur. Though the processes are complicated, scientists and land managers have developed standard tools to monitor the health of rivers. Additionally, modelling aided by computers can fine-tune the knowledge for specific rivers and watersheds.

More information about water quality found here:  Water Quality | USGS.gov 

Access USGS water quality data here:  USGS Water-Quality Data for the Nation 

Mining

Mines are one form of economic activity that produce materials needed for everyday life. However, mining activities can present a risk to water quality and ecological conditions. Mined material may contain minerals and elements that are released into the environment when material is excavated. Geochemical reactions of mined material with water and air can produce acid mine drainage. Additional elements may be introduced during the processing of mined materials. For example, milling operations historically used mercury to separate gold from other materials. When elements enter water in certain concentrations, they can alter water quality and impact ecological health.

Detecting geochemical changes and determining the cause is complicated by the varied geology within watersheds, the complex nature of these chemical and biological pathways, and the heterogeneity of how water flows through large river systems. Thus, the need for rigorous scientific investigations of these systems, to better quantify risk and protect the health of rivers and all the species that rely upon them.

More about mining and water quality here:  Mining and Water Quality 


Research Activities

The U.S. Geological Survey is assessing the baseline conditions of transboundary watersheds in the southeast Alaska region in partnership with tribal nations and government agencies. Collecting data on water quality and watershed conditions can help identify natural sources of water quality constituents such as metals. These data will contribute to a comprehensive understanding of current conditions which will serve as a reference (baseline). This information can then be used to monitor the long-term water quality during the operation of large-scale mines in the Canadian portion of the watersheds.

The USGS operates streamgages on the  Alsek ,  Salmon ,  Stikine ,  Taku , and  Unuk  Rivers. These gages record the quantity of water flowing in the rivers (discharge), which can be viewed on  NWIS . In addition to stream flow measurements, the USGS is characterizing water quality, sediment quality, biological condition, regional geology and mineralization potential.

U.S. Geological Survey Scientists engaged in various research activities and maintenance in Alaskan watersheds during the brief time when stations are safely accessible.

The immense volume of water carried in large Alaskan transboundary rivers necessitates careful planning for scientists to collect representative samples. The USGS uses rigorous methods to ensure that the water and sediment samples that they collect are reflective of conditions throughout the river. Field visits are scheduled every six to eight weeks to capture seasonal variations.

The health of the ecosystem is a major motivation for this scientific work. Stakeholders want to ensure that salmon runs continue to thrive due to their ecological, cultural, spiritual, and economic significance in the region. Additionally, it is important that ecosystems function as a resilient web of systems, especially when facing global pressures such as climate change.

Just reaching the rivers can be a challenge. Scientists travel by float plane, helicopter, and boat to access remote field sites. Steep valleys, long periods of cloudy weather, and wintry conditions add another level of complexity.

Once USGS scientists arrive at the sites, they work to capture a wealth of data, including physical properties and concentrations of major ions, metals, suspended sediment, and nutrients. Several water quality parameters, such as temperature and pH, are measured directly in the river. Other parameters, such as the concentrations of metals, must be obtained from a lab. Scientists traverse the rivers collecting bottles filled with water from multiple locations and depths in the channel. Laboratory scientists use precise techniques to analyze additional parameters that cannot be measured in the field. In some cases, they have developed new cutting-edge techniques to detect constituents from low volumes of collected material. Data from these discrete field visits are publicly available through  NWIS .


Washington Watersheds

Washington state and British Columbia share an approximately 350-mile long border along the 49th degree of latitude. The headwaters of many Washington Rivers, including the mighty Columbia River, are located in the Canadian Rockies. Some, like the Similkameen, have headwater streams in Washington which flow into Canada before returning to the United States. While cooperation and monitoring efforts by US, Canada, Tribal, First Nations, state and province governments occurs to some degree along the entire border, the USGS Transboundary group actively studies two basins, the Skagit and the Similkameen.


USGS Science in the Kootenai Watershed

The USGS is contributing scientific expertise to help stakeholders in the Kootenai watershed answer several questions. This body of research is guided by the following questions:

  • What are the current water quality conditions in the Kootenai watershed?
  • What is the nature and extent of selenium pollution in the watershed?
  • How does selenium travel and behave throughout freshwater food webs?
  • What are the most appropriate monitoring techniques to clarify selenium risk to aquatic communities, and to provide stakeholders with actionable data and information?

Water Quality Monitoring

Water quality platforms provide real-time data at various depths on Lake Koocanusa in northwestern Montana.

Water quality data are collected by the USGS and several other agencies in the Kootenai watershed. These data are available through  NWIS  and form the basis for watershed-scale assessments of selenium and other water quality trends. Scientists continue to collect water quality information at a network of stream gages and non-gaged locations throughout the watershed. These measurements will inform and refine selenium and nutrient loading determinations. Water quality is not uniform throughout the water column, especially in stratified water bodies like Lake Koocanusa, where density differentials inhibit mixing. To obtain water quality data at multiple depths, specially equipped platforms are positioned in Lake Koocanusa. They provide near-real time data, which can be viewed through the  National Water Quality Information System .

Biotic Monitoring

The USGS works with partners to collect biological samples from aquatic organisms throughout the Kootenai watershed. A 2018 study 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. A 2018–2019 study generated further baseline data on selenium and mercury concentrations in fish tissue of the Kootenai River and principal tributaries in Montana and Idaho. Current efforts seek to replicate past fish tissue sampling, establish further reference sites, and conduct spring-season sampling. Scientists are experimenting with novel methods for collecting and analyzing biological samples. For instance, algae represent a large trophic step in the concentration of selenium in the food web. However, collecting algae samples from rivers is not a simple task becasue algae grows in thin films on rocks. Scientists at the Idaho Water Science Center have developed three methods for collecting algae samples from rivers. This type of analysis not only generates robust data for understanding selenium movement in the Kootenai system, but it also contributes more broadly to establishing scientific best-practices. Another area of active research is comparison of selenium and other constituent concentrations between different tissues in the same fish species. Each tissue has the potential to accumulate selenium in different concentrations, with implications for fish health. Because there are limited tissues on these tiny fish, USGS laboratory scientists are developing new methods for doing low-mass, high precision analysis of samples.

Food Web Research

In order to comprehensively evaluate the ecological risks of selenium in aquatic environments, it is necessary to understand bioaccumulation and trophic transfer. USGS biologists are engaged in several projects examining selenium concentrations in organisms to better understand selenium pathways through aquatic food webs. Research indicates that the dietary route of exposure generally dominates bioaccumulation processes. This is important because the traditional ways of predicting bioaccumulation and toxicity in aquatic animals on the basis of exposure to water concentrations do not work for selenium, necessitating new research. The USGS has published data and reports in support of ecosystem-scale selenium modeling. This effort aims to provide an ecosystem-scale model that illustrates the site-specific range of potential selenium exposure and bioaccumulation that can inform the basis for regulatory decision-making. The biodynamic model requires information not only on dissolved selenium, but on other ecosystem compartments as well including particulate material, invertebrates, fish, and wildlife. The modeling approach brings together the main concerns involved in selenium toxicity: likelihood of high exposure, inherent species sensitivity, and close connectivity of ecosystem characteristics and behavioral ecology of predators. This approach leaves room for model refinement as more data become available and understanding of the system improves.

Idaho-Montana Project Links

Kootenai Watershed Partners and Cooperators

Kootenai Watershed NWIS Data links


USGS Science Centers

All photos taken by Transboundary research team members Alex Headman, Patrick Moran, Bob Black, Chris Mebane, and Travis Schmidt, U.S. Geological Survey

Alex Headman

AHeadman@usgs.gov

Sarah Dunn

SDunn@usgs.gov