New York’s Acid Deposition Monitoring Network

New York’s first acid deposition program was established in 1985 in response to the State Acid Deposition Control Act (SADCA). This program was designed to measure acid deposition to assess the effectiveness of sulfur control policies and other strategies aimed at reducing the effects of acid rain. The program has documented environmental improvements resulting from NO_x and SO_x control strategies. For example, the deposition of sulfate statewide has decreased by more than 75% since the monitoring program began. And these concentrations of acidic pollutants continue to decline. The SADCA established an environmental threshold value of 20 kg/ha/yr for wet sulfate deposition. Currently all monitoring sites in New York are well below that threshold.

At the end of 2012, the Department discontinued this program and transitioned six monitoring locations to the National Atmospheric Deposition Program (NADP). The transition to the NADP program has provided data for use in regulation development. The NADP has also allowed for the comparison of data from New York with other acid sensitive regions across the country. NADP sites within New York and in neighboring states can better understand acid deposition across the northeastern US.

The NADP program measures the concentrations of free acidity (H⁺ as pH), conductance, calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), potassium (K⁺), sulfate (SO₄^2-), nitrate (NO₃^– ), chloride (Cl^– ), and ammonium (NH₄⁺).

Data and reports from this program from across the United States can found on the NADP website.

Adirondack Long Term Monitoring Program

Over the years, many programs and policies, have reduced emissions of pollutants that acidified clouds, fog, snow, sleet, and rain. One such program is the Adirondack Long Term Monitoring Program. The ALTM has been documenting changes in the chemistry of lakes, streams, and clouds in the Adirondack Mountains since the 1980s.

More than 20 chemical parameters are measured in each ALTM water sample. These include sulfate (SO₄^2-) and nitrate (NO₃^–), acid neutralizing capacity (ANC), pH, and toxic inorganic monomeric aluminum (Al), all are important indicators of lake ecosystem health. Research has shown that fish and other aquatic life are less resilient when exposed to certain chemical conditions. An example of some of these conditions are an ANC below 20 microequivalents per liter (µeq/L), pH below 6, and inorganic monomeric Al above 2 micromoles per liter (µmol/L). These conditions are most likely to occur during the spring snowmelt, generally March through April.

Acid-forming air pollution has declined since the 1980s. As a result, Adirondack lakes and streams are beginning to recover. For example, the acidity level in Brooktrout Lake, thought to be fishless by the mid-1980s, has decreased about 90% since the Adirondack Lakes Survey Corporation began monitoring this lake in 1992. Brooktrout Lake is now able to support self-sustaining brook trout populations. The DEC and its ALTM partners will continue this important program to support key environmental policy efforts even as new stressors, such as climate change, emerge. More information about this can be found in the August 2014 Conservationist (PDF) article titled “Coming Full Circle”.

Monitoring SO₂ in the Adirondacks

DEC collects hourly SO₂ data in the Adirondacks as part of the monitoring network created for the NYS Acid Deposition Control Act. Over 30 years data have shown consistent declines in SO₂ connected with reductions in emissions both within and upwind of New York State. One recent result of this decrease is that the continuous monitoring method is now inadequate in rural areas. Continuous SO₂ instruments were designed to produce data that can be compared to the higher levels relevant for the NAAQS. Our review of 2008-2017 SO₂ data in the Adirondacks is available.