The Bronx River Alliance has been organizing and assisting volunteer groups to conduct weekly water quality monitoring for the past several years. Water quality monitoring data for the Bronx River is also available dating back to the early 1990s, collected under the direction of the Alliance’s predecessors, Bronx River Restoration. Combined, over 1,000 water quality samples have been collected on the Bronx River since 1990. Analysis of this large data set was undertaken to summarize the data, identify water quality trends and data gaps, and make recommendations for the water quality monitoring program to improve the quality, usefulness, and educational value of future monitoring data for the Bronx River.