Specific conductance and water chemistry data for selected rivers and creeks in Yellowstone National Park, beginning in 2010 (ver. 3.0, November 2025)

Measuring the thermal output of Yellowstone’s large magmatic system is not straightforward, as there are thousands of thermal features spread across 3470 square miles. One way to capture and integrate the thermal discharge from this broad area is to monitor river chemistry, because thermal water discharge eventually enters a nearby river, which acts as a collection and delivery system. Nearly all the dissolved chloride in rivers that drain Yellowstone comes from emerging hot spring water heated underground by underlying magma. Monitoring river chemistry is therefore an important way to track changes in Yellowstone’s hydrothermal system. By monitoring the chloride flux, the hydrothermal discharge and heat flux from Yellowstone can be estimated and temporal variations can be used to identify changes in the deep hydrothermal system, earthquake activity, geyser eruptions, and quantify the impacts of floods and wildfires.

The U.S. Geological Survey (USGS) and the National Park Service (NPS) have collaborated on chloride flux monitoring of the major rivers since the 1970s. In the past, researchers collected water samples from the major rivers draining Yellowstone National Park, but funding restrictions, winter conditions, and the great distances between sites limited the number of samples collected annually. Beginning in 2010, specific conductance, which is relatively easy to measure and can be automated, has been used as a proxy for chloride. The use of specific conductance probes at the various monitoring sites enables a more consistent estimation of chloride flux. Consistent monitoring is useful to identify changes in river chemistry due to geyser eruptions, rain events, or changes in thermal inputs caused by earthquakes or other natural events. The use of specific conductance as a proxy for chloride requires quantification of the relationship between specific conductance, chloride, and other geothermal solutes and the relationship needs to be periodically verified. This data release contains specific conductance measurements (collected every 15 minutes) and water chemistry data from monitoring sites along the Madison, Firehole, Gibbon, Snake, Gardner, Fall, and Yellowstone Rivers, and from Tantalus Creek. For several of the monitoring sites, there are periods of time when specific conductance is not reported because the data was likely unreliable due to failure or fouling of the specific conductance probe. There are also specific conductance and discharge data available from the USGS National Water Information System (USGS NWIS, https://waterdata.usgs.gov/nwis/rt).

The following list details the sites included in this data release and the National Water Information System site identification numbers.
Sites with both continuous specific conductance and discrete water chemistry data:
Yellowstone River near Corwin Springs, 06191500;
Yellowstone River at Yellowstone Lake Outlet, 06186500;
Gardner River near Mammoth, 5 km downstream from 06191000;
Firehole River near West Yellowstone, 06036905;
Firehole River at Old Faithful, 06036805;
Fall River, Idaho, 2.5 kilometers downstream from 13046995;
Gibbon River at Madison Junction, 06037100;
Madison River near West Yellowstone, 06040000;
Snake River near Flagg Ranch WY, 1 km downstream from 13010065;
and Tantalus Creek at Norris Junction, 06036940.

Sites with only discrete water chemistry data:
Snake River below Jackson Lake Dam, 13011000;
Boiling River, 06190540;
Henrys Fork near Ashton ID, 13046000;
Lewis River at Lewis Lake outlet;
Nez Perce Creek;
and Sheffield Creek.

First posted - January 28, 2019 (available from author)
Revised - May 6, 2020 (version 2.0; available from author)
Revised - November 25, 2025 (version 3.0)

NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 3.0.