Water quality summary for the Lamar River, Yellowstone River, and Madison River in Yellowstone National Park: Preliminary analysis of 2016 data

Levandowski, Mary

he Greater Yellowstone Inventory and Monitoring (I&M) Network is a National Park Service (NPS) program charged with monitoring ecological vital signs in three 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 2016. 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 2016. Reese Creek, identified for impairment due to a fish-passage barrier, was monitored during 2016 and the monitoring report prepared by Yellowstone National Park is included as an appendix to this report. Results presented here for the Lamar, Yellowstone, and Madison rivers include annual and long-term 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. Results in this report 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 occur-ring in late summer and extending into fall. The hydrographs for the Lamar and Yellowstone rivers are indica-tive of snowmelt driven systems while the hydrograph for the Madison River suggests greater contributions from groundwater. In 2016, flows were below the historic mean at each station for a majority of calendar days. The total volume at all three stations was lower in 2016 than the historic mean. Peak flows at the Lamar River occurred earlier than the historic mean, while the Yellowstone was consistent with the historic mean. All three stations exhibited higher flows in October 2016 that corresponded with above-average precipitation totals for that month. Notably, the Madison River peak flow occurred in October with a comparable discharge to the early, snowmelt-generated peak flow. The daily flows at all three rivers were generally below the 25th percentile of long-term flows from summer to fall. 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 near West Yellowstone exceeded the state of Montana’s chronic life criteria during all sampling occasions. 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 contri-butions relative to the other monitored waters.

Water quality summary for the Lamar River, Yellowstone River, and Madison River in Yellowstone National Park: Preliminary analysis of 2016 data

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