EPA Water Quality Data
From the US EPA, data on water quality from surface and ground waters; some of the data is from occasional sampling and some is from regular monitors. Nitrogen and phosphorus are frequently included in the testing, so are often in the list of parameters for a site.
Provides annual summaries of air pollution data for the entire United States. Produces reports and maps of air pollution data based on criteria you specify. Data include:
Monitoring data (Carbon monoxide (CO), Nitrogen dioxide (NO 2), Ozone (O 3), Sulfur dioxide (SO 2), Particulate matter (PM 10 and PM 2.5), and Lead (Pb)
Emissions data (Carbon monoxide (CO), Sulfur dioxide (SO 2), Particulate matter (PM 10 and PM 2.5) and three precursors/promoters of criteria air pollutants: Volatile organic compounds (VOC), Nitrogen oxides (NOx) and Ammonia (NH 3)