Water quality summary for the Lamar River, Yellowstone River, and Madison River in Yellowstone National Park: Preliminary analysis of 2015 data

Levandowski, Mary; Ray, Andrew

The Greater Yellowstone Inventory and Monitoring Network (GRYN I&M) is a National Park Service (NPS) program charged with monitoring ecological vital signs in four national park units in Wyoming, Montana, and Idaho. This report focuses on discharge and water quality monitoring efforts in the Lamar, Yellowstone, and Madison rivers in and surrounding Yellowstone National Park for calendar year 2015. Monitoring activities for Soda Butte Creek, a 303(d)-listed stream that is a tributary to the Lamar River, will be included in a separate report for calendar year 2015. Reese Creek, identified for impairment due to a fish-passage barrier, was monitored during 2015 and the monitoring report prepared by Yellowstone National Park is included as Appendix C. Results for the Lamar, Yellowstone, and Madison rivers that are presented in this report include annual and longterm discharge summaries and an evaluation of chemical and suspended sediment conditions relative to state and federal water quality standards. Sampling locations on the Lamar and Yellowstone rivers are co-located with USGS streamflow gages. The Madison River sampling location is located at the Montana Hwy 191 bridge crossing downstream of the USGS streamflow gage. These results are considered provisional, and therefore, may be subject to change. River Discharge Hydrographs for the Lamar River near Tower Ranger Station, Yellowstone River at Corwin Springs, and Madison River near West Yellowstone exhibit a general pattern of high early summer flows and lower baseflows occurring in late summer and extending into fall. The hydrographs for the Lamar and Yellowstone rivers are indicative of snow-melt driven systems while the hydrograph for the Madison River suggests greater contributions from groundwater. In 2015, flows were below the historic mean at each station for a majority of days. The daily flows at the Lamar and Yellowstone rivers were above the historic mean at peak flows and generally below historic average flows the remainder of the year. Daily flows at the Lamar River were above the historic average flows until early May but flows, including peak flows, for the remainder of the year were near or below the 25th percentile of long-term flows. Water Quality Monitoring Water quality at sampling locations exhibited seasonal variability over the sampling period. Across all sites, total arsenic, calcium, chloride, and sodium concentrations were generally at minimum levels during high flows. Total arsenic levels in the Madison River at West Yellowstone exceeded the state of Montana’s chronic life criteria during all but one sampling occasion. Arsenic in the Madison River is likely naturally occurring from geothermal geology in the watershed. Other water quality results also suggest Madison River is receiving greater groundwater contributions relative to the other monitoring waters.

Water quality summary for the Lamar River, Yellowstone River, and Madison River in Yellowstone National Park: Preliminary analysis of 2015 data

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