The City Hall press corps got a big laugh earlier this week when Mayor Daley colorfully lashed out at the Environmental Protection Agency -- and by extension, the Obama administration -- for urging regional officials to implement tougher water quality standards in the Chicago River. But local government consultant Todd Connor says that reporters directed their question at the wrong person. "Why do we go to the mayor for a comment?" he says, noting that Daley doesn't have any control over "the elected body who makes the relevant policy decisions."

In this case, that government entity is the Metropolitan Water Reclamation District (MWRD).  The new federal EPA letter, delivered on April 15, is the latest development in a ongoing legal fight over river decontamination between the MWRD, the Illinois EPA, the city of Chicago, and a bevy of environmental organizations.  Here's an quick history lesson of the controversy:

Like another prominent water dispute -- the Asian carp debate -- the story begins over a century ago with the reversal of the Chicago River. For decades, residents of Chicago dumped their personal and industrial sewage into the river, which naturally flowed into Lake Michigan, the city's primary source of drinking water. To improve public health, the agency that is now the MWRD built the Chicago Sanitary and Ship Canal and reversed the flow of the wastewater using a series of navigation locks. Folks still polluted the waterway, but now it flowed out to the Mississippi River instead.

Fast forward to 1972. That's the year the federal government passed the Clean Water Act, which mandated that most surface waters would need to meet certain baseline water quality standards. It's also when MWRD and local environmentalists ratcheted up their stewardship of the Chicago River. Local environmental groups like Friends of the Chicago River focused on habitat restoration. MWRD launched the Tunnel and Reservoir Plan, known more frequently as "Deep Tunnel," an ongoing multibillion-dollar project to drudge a network of tunnels and reservoirs that capture and redirect contaminated storm runoff. And officials across the region began to see both the environmental and economic benefits of a healthy river. In just 30 years, for example, MWRD says the number of fish species present has jumped to 60 from just five. And in 2005, the Daley administration produced a "Chicago River Agenda" including changes intended to transform the river into "Chicago’s second shoreline.”

Despite the enormous progress, the Illinois Environmental Protection Agency saw room for more improvement. In the fall of 2007, it released a comprehensive report calling for new quality standards to protect people and wildlife that use and live in the river's water. Along with issues of temperature control and dissolved oxygen levels, the body submitted what's called a "rulemaking proposal" recommending that the region could do more to reach the river's "highest attainable use" value -- meaning disease-causing bacteria would have to be eliminated. Doing so would require the MWRD to invest in new technologies to disinfect effluent that flows from three of its Chicago-area sewage treatment plants.

Last month's letter from the federal EPA ups the ante even further, recommending that portions of the river be made safe for human recreational use.

Environmentalists thinks a comprehensive detox is long overdue. Chicago is the only major city in America that doesn't disinfect its wastewater before sending it back into the surrounding system. And as Tribune environmental reporter Michael Hawthorn noted, during heavy rains the city's sewers spill billions of gallons of waste into the river every year. "We're an outlier," says National Resources Defense Council Midwest program director Henry Henderson.

The issue of whether to set higher quality standards is currently in the hands of the Illinois Pollution Control Board, which must first accept any EPA recommendations before they can be enforced. Not surprisingly, it's hotly contested.

Essentially, MWRD contends that there is no scientific basis backing up the claim that exposure to the levels of waste currently in the river represents a risk to humans. (They are still waiting for final results of a study conducted by the University of Illinois-Chicago testing the relationship between water contamination and public health.) More importantly, the district is concerned with cost. MWRD estimates updating the treatment centers to comply with the latest federal recommendations would cost local taxpayers $623 million, money that could otherwise be used to finish the Deep Tunnel. The Illinois EPA puts the price at a more modest $242 million.

Henderson considers MWRD's response "a bit of a head-scratcher." On the one hand, the body promotes all of the ecological improvements its made over the past three decades. But when it's suggested that more could be done, the agency falls back on old habits, characterizing the river as nothing more than a waste conveyor belt -- and blocking further reforms in the process. "These waterways serve the need for urban drainage and commercial navigation," MWRD general superintendent Richard Lanyon told reporters yesterday. "Which is it?" asks Henderson in response, adding that the body's intransigence is "incomprehensibly inane."

Meanwhile, while Daley has done a great deal to improve water quality and has no real control over the next steps being proposed, his derisive comments about the feds' letter only give MWRD cover.

Both the Illinois EPA and MWRD expect the disinfection debate to continue for several more months. Connor, however, thinks the Obama administration's involvement is noteworthy, calling the letter "both meaningful and relevant." And Debra Shore, a MWRD commissioner and clean water champion, calls the debate healthy. "It's good to see that people care a lot about the quality of our waterways," she says.