Number of manatees that have died over the past year in Florida's Indian River estuary due to a massive algae bloom caused by sewage, manure and fertilizer runoff known as "nutrient pollution" because it contains high levels of nitrogen and phosphorus: about 280

Number of pelicans that have died there: at least 300

Number of dolphins found dead: at least 51

Years in which the estuary's dolphins suffered similar die-offs related to algae: 2001, 2008

Month in which Florida officials announced that estuary algae samples tested positive for toxins that can be harmful to wildlife, people and pets: 8/2013

According to scientific surveys conducted in 2011 and 2012, factor by which nitrogen levels in the estuary's southern waters exceed acceptable levels: 3

Estimated annual cost to Floridians of the pollution-caused algae outbreaks: $1.3 billion to $10.5 billion

Amount by which an algae outbreak that occurred several years ago in the Florida coastal communities of Stuart, Hobe Sound, Port Salerno and Jensen Beach permanently lowered waterfront property values: $500,000

Year in which the Environmental Protection Agency entered a binding legal agreement with environmental advocates under the Clean Water Act to limit the pollution that leads to the algae overload: 2009

Number of people who wrote to the White House last year urging the Obama administration to stand firm on imposing federal standards to limit the pollution of Florida waters: 40,000

Date on which the EPA and the Florida Department of Environmental Protection announced plans to back away from the pollution controls specified in the 2009 settlement: 3/15/2013

Number of people -- some of whom have suffered health problems from the pollution -- who showed up at a protest last weekend in Stuart, Fla. calling on the government to take action against polluters: more than 2,500

Date for which the next protest is planned: 8/11/2013

(Click on figure to go to source. To see more photos of Florida's toxic algae crisis, click here.)