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Home , Madison River

The Fate of Geothermal Mercury in the Madison and Missouri Rivers, and

David Nimick & Rodney Caldwell U.S. Geological Survey Helena, Montana

Old Faithful Don Skaar & Trevor Selch Montana Fish, Wildlife and Parks Helena, Montana U.S. Department of the Interior U.S. Geological Survey Previous Hg Studies

. Hg concentrations in water and gases emitted from YNP geothermal springs (~10 studies) . One 24-hr Hg data set for Madison River (Nimick et al., 2007) . Hg in four YNP trout (survey of western US streams, Peterson et al., 2007) . Hg in sediment and trout in Hebgen, Canyon Ferry, and Hauser Lakes (survey of Montana lakes, Phillips and Bahls, 1994)

Norris Geyser Basin Study Area

(Sonderegger and Bergantino, 1981)

Lower Madison River valley

Madison River in YNP Study Objectives

. Determine Hg concentrations in water, sediment, and fish . Evaluate potential health and ecological risk . Quantify the geothermal Hg load from YNP . Assess the overall fate and transport of Hg in this large river system . Be efficient considering the long study reach and limited budget Sample Collection -- Fish & Sediment Streamflow Unfiltered Total Mercury in Water Unfiltered Total Mercury in Water

USEPA standards Baseline Hg values for lakes in MCL = 2,000 ng/L Glacier National Park Acute = 1,400 ng/L 0.35 – 2.9 ng/L Chronic = 700 ng/L (Watras et al., 1995) Total Mercury in Sediment Total Mercury in Fish Hg Fate: Total Mercury Loads Mercury Fluxes for Madison River in YNP Output: . 7.0 kg/y—Annual load leaving YNP via the Madison River . based on mean total unfiltered Hg concentration (17 ng/L) and mean daily flow (456 ft3/s) for 2000-09 at Madison River near West Yellowstone. Inputs: . 4.6 kg/y—Annual wet deposition on watershed . based on measured deposition for 2005-09 at NADP site WY08 in YNP and drainage area of 1,090 km2 . ?? kg/y—Annual load from geothermal basin Hg Fate: Hg Budget for

Net unaccounted Atmospheric loss is 6.5 kg/y deposition Ungaged (volatilization and tributaries 0.4 sedimentation) 0.08 Hebgen Lake 7.0 0.95 Madison River Madison River near West below Hebgen Yellowstone Lake

Units for all values = kg/y Potential Unknown Hg Source?

Hg loads (g/s) do not add up: Madison + Jefferson + Gallatin ≠ Missouri 10.6 + 4.9 + 1.8 < 27.4

Possible Sources: 1. Warm springs near Toston (46 ft3/s) 2. Mobilization from Hg-rich(?) sediment in lower Madison valley 3. Sampling/analytical error Conclusions

. Geothermal springs in YNP are the primary Hg source to the upper Madison River . Hg concentrations are above human and ecological risk levels in and/or above Hebgen Lake . Hebgen Lake removes ~90% of the geothermal Hg load from the Madison River . Future study ideas: . Why are Hg levels slightly higher in the Gallatin & Jefferson Rivers than in the Madison River? . What is the source of the extra Hg load in the upper ? . What is the Hg flux from geothermal springs outside of YNP? Madison River, Montana Hg Fate: Tracers of Geothermal Water Relations among Sampled Media