EPA oversees the Long Term Monitoring (LTM) and Temporally Integrated Monitoring of Ecosystems (TIME) programs to track the status of acidified and acid-sensitive waters. These programs measure critical chemical variables which provide insights into many measures of ecosystem health. The LTM and TIME programs are complementary monitoring networks used to better understand long-term trends in acidification and recovery in the Northeastern and Mid-Atlantic United States. Both programs are operated with numerous collaborators in state agencies, academic institutions and other federal agencies.

View Monitoring Surface Water Chemistry for more detailed information about the LTM and TIME monitoring programs.

View a list of publications that have drawn on LTM and/or TIME data below.

• Publications Drawing on TIME/LTM Data, 1985-2007 (PDF)(8 pp, 136 K, 05/2009)