From the buried lede department: In the Wall Street Journal's account on Thursday of the increasingly loud complaints among dairy farmers that Dean Foods (DF) is responsible for historically low milk prices, we learn only in the closing paragraphs that "many" economists think simple economics are to blame.

In 2001, the two largest dairy producers, Dean Foods and Suiza Foods, merged to create a dairy behemoth, with a market capitalization of $2.84 billion and annual sales of more than $12 billion.

If you inspect the carton of milk in your fridge, the chances are fairly good that, no matter what brand it's sold under, it came from Dean Foods. You might want to check your butter and your ice cream, too.

In a letter to the Justice Department last month, two Democratic sentors, New York's Charles Schumer and Wisconsin's Russ Feingold, asserted that the company controls about 80 percent of the milk market in Michigan, Massachusetts and Tennessee, and about 70 percent of the market in New England. "Something is rotten in the state of Denmark," Schumer said.

But does that mean that Dean Foods has monopoly pricing power? After all, fully six years after the Dean-Suiza merger, milk prices soared. If Dean has power over the market, the company didn't exercise it in 2007 and 2008. Or maybe it did. Maybe prices would have soared even more if the dairy industry looked more like it did 20 years ago, with lots of smaller, regional dairy producers in the market.

Still, underlying the recent price movements has been simple supply and demand. In response to swiftly rising prices, U.S. farmers expanded their herds, adding, according to the Journal, 190,000 cows. But then came the recession, and slackening demand, leading to a massive oversupply and much lower prices. In the past year, prices paid to dairy farmers have fallen by more than a third.

The question of monopoly will come before the Senate Judiciary Committee during a hearing to be held tomorrow in Vermont.

The timing might be slightly off. As mainstream media outlets continue to report on falling milk prices, trade publications are beginning to report that prices are actually ticking back up again, thanks in part to the recovering economy, as well as farmers—again, responding to market conditions—thinning their herds. Further, in August the USDA  raised the levels of price supports, removing "millions of pounds of product from the market," according to the California Farm Bureau Federation. (Doing so runs the risk of actually depressing prices further in the long run, the Federation's article notes, because it gives farmers an incentive to keep up production.)

Few expect a big spike in prices, but Ag Weekly reports that USDA’s Economic Research Service has forecasted that prices should "recover from 2009’s lows next year," though they will likely "remain well below the highs of 2007 and 2008."

Farmers are angry in Europe, too. In Belgium this week, farmers sprayed millions of gallons of milk onto fields. Farmers in the European Union, the world's largest producer of milk, have also blocked deliveries, and dumped milk in front of government buildings in protest of what they call a failed attempt by the EU to liberalize the dairy market.

Such is the complexity of government intervention into dairy markets—price supports, quotas, import and export regulations, and incentives—that it seems unlikely that tomorrow's hearing will truly reveal how much market power Dean Foods really has.