District of Columbia Open Data vs EPA

Open Data DC is the District of Columbia government's catalogue of public datasets, spanning crime incidents, GIS/mapping layers, and financial and demographic data, published on an Esri ArcGIS Hub site. Datasets are queryable keyless through the Hub's search and DCAT feed APIs and through individual ArcGIS Feature/Map Services, returning JSON, GeoJSON, CSV, or shapefile depending on the layer. No account or API key is required to read data.

EPA's Envirofacts platform exposes the agency's environmental compliance and monitoring databases — air quality, drinking water systems, the Toxics Release Inventory, hazardous waste, and Superfund sites — through a keyless REST API at `data.epa.gov/efservice`. Any of the underlying tables can be queried by building a URL from the table name, filter columns, and an output format, with results returned as JSON, XML, CSV, or Excel. EPA's Developer Central site separately documents smaller topic widgets built on the same data.