Provisional Real-time Stream-flow Data
http://volcanoes.usgs.gov/yvo/hydro_data.html

U.S. Geological Survey


This USGS website provides real-time and historical stream-flow data from the major rivers draining Yellowstone National Park. Data from thirteen gaging stations within and around the Park can be selected from a list or map. Data and graphs are available for gage height, stream discharge, and in some cases, temperature. Water quality sampling results and a link to EPA information on the watershed are also available for all stations.

This resource is referenced here:
Subject: Geoscience:Hydrology
Resource Type: Datasets and Tools:Datasets
Topics: Hydrosphere/Cryosphere
Focus on Yellowstone: Surficial geology and hydrology