A plane with a banner is flying over the Crisler Center on Saturday ahead of the Michigan-Michigan State game, but it's not about basketball.

UltraViolet, a national women's advocacy organization, commissioned a plane to fly with a banner bearing the message "Snyder poisoned kids in Flint @UltraViolet."

The plane is flying over Ann Arbor from noon to 3 p.m. Feb. 6. The men's basketball game tip-off is 2 p.m.

The organization wants to draw attention to the lead crisis in Flint and urges Gov. Rick Snyder to resign.

Shauna Thomas, co-founder of UltraViolet, said she believes Snyder knew about the lead in the water for at least a year.

"His actions have resulted in more than 10,000 children and pregnant women being exposed to dangerously toxic levels of lead that will cause severe brain, nervous system and liver damage that will haunt them for the rest of their lives," she said in a statement. "It is time that all Michigan residents--Spartans and Wolverines alike--stand up and demand that Governor Snyder resign immediately."

Snyder's Press Secretary Dave Murray disputed the claim, saying the governor didn't know about the elevated lead levels until Oct. 1, 2015.

MLive reported on data showing elevated lead levels in the water on Sept. 2, 2015.

The governor "responded aggressively and immediately with a 10-point plan focusing on addressing immediate and long-term efforts to protect the health and safety of Flint residents," Murray said in an email to MLive.

"Those efforts include proposing $70 million in assistance, mobilizing the National Guard and pushing to expand vital health programs for the city's children. Governor has requested the federal government expand the Women, Infants & Children program and extend Medicaid to everyone in Flint under age 21," Murray continued.

In April 2014, a Snyder-appointed emergency manager made the decision to change Flint's drinking water source from Lake Huron to the Flint River. The city didn't treat the water to make it less corrosive, causing lead to leach into the water.

A Hurley Medical Center physician found the number of children in the city with elevated blood levels of lead nearly doubled once the city switched to Flint River water.

Snyder has faced criticism for the state's role in the water crisis, with politicians and celebrities calling for him to resign.

The governor has said he intends to fix the problem and has no plans to resign.

Editor's note: The quotation mark was moved in the headline to more accurately reflect what the banner read.

Lindsay Knake is a cops and courts reporter for The Ann Arbor News. Follow her on twitter or contact her at 989-372-2498 or lknake@mlive.com.