The Lamar River basin of northeastern Yellowstone National Park (YNP) contains some of the most unique and natural benchmark vegetation conditions and important wildlife habitat in the Greater Yellowstone region, including the Northern Range of YNP.  Broad glacial valley floors provide grassland winter range forage for ungulates.  Alluvial channels are critical habitat for native fish populations.  The Lamar River is a tributary of the larger Upper Yellowstone River basin.  The Lamar River main channel flows predominantly to the northwest.  It is joined by many tributary streams, including Soda Butte Creek and Slough Creek, and then joins the Yellowstone River near Tower Junction, just below the Grand Canyon of the Yellowstone.  USGS gage station 06188000 is on the Lamar River near the Tower Ranger Station.  The elevation at this station location is 1828 m (6000 ft).  The highest point in the Lamar basin is 3429 m (11,250 ft) and the total area coverage is 1709 km² (660 mi²).

Protection of water resources and the catchments from which it is derived remains critical to the environmental integrity of YNP and downstream areas.  Large-scale hydrologic processes that could be impacted in the Lamar Basin (and YNP generally) by climate warming include: later onset of and reduced snowpacks, earlier snowmelt, more frequent flood events, receding glaciers, higher evapotranspiration rates, more frequent and longer droughts, more frequent and more intense wildfires, reduced summer and fall stream flows, and the loss of riparian vegetation leading to further increase in stream temperature and soil loss.

Simulation modeling is one way to begin to address these climate change issues in YNP.  The Snowmelt Runoff Model (SRM) is designed to simulate and forecast daily stream flow in mountain basins where snowmelt is a major runoff factor.  SRM was originally developed by Martinec (1975) for small European basins.  Since then, the model has been applied in at least 80 basins situated in 25 different countries and in basins as large as 122,000 km².  The SRM is a simple degree-day model that requires daily input for temperature, precipitation and snow cover extent.  Additionally, the model has 8 parameters which can either be derived from measurements or estimated by hydrological judgment, taking into account the basin characteristics, physical laws, and theoretical or empirical relationships.  Because the SRM is a semi-distributed model, the Lamar watershed must be split up into altitudinal zones that encompass between 500-750 m of elevation.  Consequently, the entire 2601 m elevation range was divided into three zones, which are delineated by the black lines in the Study Area map.  Thus far, we have run the SRM on the Lamar basin for the 2003 snow melt season (March - June).  NASA satellite data in the form of MODIS snow cover products have been used to develop daily snow cover depletion maps for the Lamar elevation zones.