Last December, you probably remember hearing news of the massive environmental disaster in Tennessee?the major coal ash spill? What you probably don't remember is that the ash spill wasn't reported in major news outlets until a full two days after it occurred.

Why exactly this was the case remains somewhat murky: maybe national news outlets didn't deem it sexy enough, maybe local news stations were afraid of political repercussions—who knows? But one unlikely source had the goods on the story without even knowing it did: Twitter. Yes, Twitter, the mini-blog/social media website that traffics solely in "tweets," or messages that are 140 characters or less.

And Twitter is what broke the ash spill story.

Mother Earth News explains how Twitter was the go-to source for the story long before it was even Google-able:

With a 140-character limit on individual posts, Twitter looks like a poor conduit for in-depth information. But you can fit just about any URL in 140 characters. Twitter also has a simple, unique feature called a hashtag. Type in a key word preceded by the "#" in Twitter?s search function, and you'll be taken to every Tweet that includes the phrase — in this case, "#coalash."

Ahhh—so there is a use for Twitter beyond my lame-brained messages to buddies like: "just had lo mein. chinatown. so bomb." Using the hashtag, you can poke around the inner recesses of Twitter to find news that isn't even news yet—which means getting the inside scoop on green goings on long before they break on the New York Times. In this case, the coalash hashtag lead to some genuine action:

Amy Gahran is a Boulder, CO media consultant who specializes in both online and environmental journalism. "I saw a big story that I thought was interesting, and found almost nothing in the national media," she told me. Within a day or two, Gahran had spearheaded a hashtag effort to bring all available info on the spill to a national audience of Twitterers. Other contributors included RoaneViews, a news and info website for the community near the Kingston power plant; the Knoxville News-Sentinel and Nashville Tennessean, two state dailies that have covered the story aggressively; and Jeffrey Levy, an EPA Web Information Officer, volunteered Agency maps and stats on the facility.

And from there, the story grew into a force that couldn't be ignored by larger news outlets—in essence, Twitter was the vehicle for bringing the Tennessee ash spill to national attention.

So if you're not on Twitter yet, log on. You might help break the next big green story.

Once you get started, don't forget to follow us @PlanetGreen and these other great-green twitterers.