GLACIER MASS BALANCE MONITORING AT NORTH CASCADES AND MOUNT RAINIER NATIONAL PARKS

The hundreds of glaciers in the Cascade Range are a vital component of Pacific Northwest aquatic and terrestrial ecosystems and hydrologic systems. They influence stream flows, flooding, soil development, vegetation distribution, water quality, and are unique indicators of climate change. The National Park Service (NPS) monitors mass balance of four glaciers in North Cascades National Park (NOCA) and two glaciers in Mount Rainier National Park (MORA). Monitoring includes direct field measurements three times a year of accumulation and ablation using the stratigraphic system and decadal photogrammetric re-mapping. At NOCA, Noisy Creek, Silver Creek, and North Klawatti Glaciers have been monitored since 1993 and a fourth, Sandalee, since 1995. Direct measurements show net loss for Noisy Creek and North Klawatti during the last ten years while Silver Creek and Sandalee show net growth. Differing aspects, altitude ranges, and east to west proximity to the Pacific Crest explain these differences. At NOCA the geodetic cumulative balance for a 6 to 9 year period has been determined from photogrammetric re-mapping. Comparison of the results between direct and geodetic cumulative balances will be discussed. Annual variations are similar for the four glaciers and nearby South Cascade Glacier. Glacier summer balance data are used to estimate glacial contribution to summer (May 1-September 30) streamflow for Baker River (watershed area: 831 km2), Thunder Creek (272 km2), and Stehekin River (769 km2) watersheds. Depending on the year and the watershed, glaciers contribute between 6 - 45 % of total summer runoff. Relative importance of glacier contribution to stream flow varies from 8.8 % in the maritime climate of Baker River to 9.7 % in the continental climate of the Stehekin Valley. The Stehekin watershed has ~1/2 the area of glaciers as the Baker. At MORA, we are in the second year of mass balance monitoring of Nisqually and Emmons glaciers. This spring we identified the maximum winter accumulation altitude at ~ 2250 m on Nisqually Glacier and at ~ 2000 m on Emmons Glacier. Summer balance near the terminus of the Nisqually Glacier in 2002 was 8.2 m water equivalent, nearly twice that of the summer balance at an equivalent altitude on Noisy Glacier! Final results from the 2003 balance year will be presented.