Don't say the WatchDog did not tip you off on this. The January 16, 2013, release of EPA's Toxics Release Inventory (TRI) National Analysis slices and dices the data in ways you can use to come up with stories that have unusual impact.
Many news outlets content themselves with stories that go: "Our state ranks 13th dirtiest but is 9% cleaner this year." Those stories were mostly written within a few days of EPA's release. Some other good stories are still waiting to be written.
The TRI, established by a 1986 law, is probably the oldest and biggest public pollutant database program, and the foundation for scores of other federal environmental data projects. One premise was that if Congress forced industries merely to disclose the toxic chemicals they were handling and putting into the environment, then regulation would not be necessary.
EPA had already released preliminary TRI data for the latest available year (2011), but its National Analysis makes for easier reporting, if only because data is collated by state.
But the National Analysis offers other goodies — for example, an analysis of toxics handling by collating the parent companies of each facility nationwide. Many of the predictable chemical companies show up on the list, but one surprise is to see Koch Industries Inc. (sponsor of many anti-regulatory campaigns) showing up fourth in nationwide rankings. Look further: Who is Teck American Inc., holder of first place on the list? (Hint: it's Canadian.)
Also useful is an analysis by industry sector. This allows you to separately filter releases by the mining industry (high in poundage but not necessarily in relative toxicity) from releases by the chemical industry.
One fact that may commend the TRI National Analysis to gumshoe journalists is that industry and EPA tried hard to kill it during the Bush years — and almost succeeded.
The best place to start looking at the National Analysis is the TRI homepage,  which leads to the most recent National Analysis and pretty much everything else. There is a boatload of state and regional takes on the TRI on the EPA press page dated January 16, 2013.