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Monitoring Surface Water Chemistry

TIME/LTM | Current TIME/LTM Regions | Map of Sites | Regional Trends

Surface water chemistry is a direct indicator of the potential effects of acidic deposition and the overall health of aquatic ecosystems. Two EPA administered monitoring programs provide information to assess the response of acid-sensitive watersheds most impacted by acidic deposition: the Temporally Integrated Monitoring of Ecosystems (TIME) project and the Long-Term Monitoring (LTM) project. Both programs are operated cooperatively with numerous collaborators in state agencies, academic institutions and other federal agencies. The total annual cost of operating these programs is approximately $1 million dollars. Augmenting these core programs are periodic sampling surveys of lake sub-populations especially sensitive to acidification or recovery. The goal of these projects is to track whether the Clean Air Act Amendments (CAAA) (Plain English Guide to the Clean Air Act) have been effective in reducing the acidity of surface waters in New England, the Adirondack Mountains, the Northern Appalachian Plateau, the Ridge and Blue Ridge provinces, and the Upper Midwest (sampling has been discontinued).

Chemical Variables monitored in TIME/LTM

Acid Base Variables Major Ions Trace Metals Other
acid neutralizing capacity (ANC), pH anions: sulfate (SO42-), nitrate(NO3-), chloride(Cl-) total and inorganic monomeric Aluminum dissolved organic carbon (DOC), conductivity, color
cations: calcium, magnesium, sodium

*dissolved inorganic carbon (DIC), fluoride (F-), ammonium (NH4) and silica (SiO2) are also collected at some sites

Data and Information:


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