Anglers on their way into the north woods of Wisconsin this Labor Day weekend won't be seeing one important message: Mercury-with-fins could be tugging on the other end of their lines.

This month Environment 2004, a political group aimed at exposing the Bush administration's anti-environmental record, tried to place this advertisement on two billboards along a highway used by vacationers from Madison and Milwaukee. But the group found that Lamar Advertising of Central Wisconsin wasn't so keen on its message.

The ad, which reads "Mercury. It's what's for dinner. Served up by the Bush Administration," carries a photo of a rather sick looking white bass. "We believe the ad making Bush responsible for mercury poisoning is not appropriate for our market in central Wisconsin," an employee of Lamar wrote to Environment 2004 in an email rejecting the ad this earlier this week.

Wisconsin was one of the 48 out of 50 states listed by the Environmental Protection Agency in a report Tuesday detailing warning advisories about levels of mercury and other toxins in the rivers and lakes of America.

"The single largest source of mercury are power plants," Aimee Christensen, executive director of Environment 2004, told Salon. "At the end of the Clinton Administration, the E.P.A. was moving forward on rule-making to regulate mercury from coal-fired power plants. The Bush administration stopped that process. Instead it has proposed that mercury not be considered a hazardous pollutant under the Clean Air Act, and has delayed court-ordered regulation of mercury from power plants."

Even very low concentrations of methyl mercury in the blood of a pregnant woman can lead to permanent learning and other cognitive problems for her future child, according to Christensen. The E.P.A. cautions women who want to become pregnant, are pregnant or are nursing to limit their consumption of certain types of fish.

Environment 2004 isn't the only liberal political group that's had trouble buying public ad space. This summer Project Billboard had to sue to bring their Cost of War ticker billboard to Times Square, which will now run during the Republican convention. And in March 2003, Working Assets couldn't find a billboard company near the President's ranch in Crawford, TX, willing to carry their ads declaring "Support our troops. Bring them home now."