2010 Progress Report - International Joint Commission

Declines in sulphate deposition levels are the likely
result for many of the improving trends in ANC, but
ANC levels still lag declining sulphate concentrations
in many of the monitoring sites. From 1990 to 2007,
monitoring sites that showed increasing ANC levels
(statistically signifi cant improving trend) were in the
Figure 34. Trends in Lake and Stream Water
Chemistry at LTM Sites, 1990–2007 –
Sulphate Ion Concentrations
Adirondacks and Catskills (50% of sites). Only a few
sites (12% of sites) in New England had statistically
signifi cant increasing trends in ANC. Streams in the
Appalachian Plateau and Blue Ridge showed few
statistically signifi cant trends in ANC (Figure 36).
Figure 35. Trends in Lake and Stream Water
Chemistry at LTM Sites, 1990–2007 –
Nitrate Ion Concentrations
Scientific and Technical Cooperation and Research
Source: US EPA 2010
Source: US EPA 2010
Figure 36. Trends in Lake and Stream Water
Chemistry at LTM Sites, 1990–2007 –
ANC Levels
Source: US EPA 2010
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