Heavy rains and a hot summer harmed the Chesapeake Bay's health last year, earning it the second worst grade on a yearly report card issued Tuesday by the University of Maryland's Center for Environmental Science.

The center gave the bay a D+ in 2011, scoring only slightly better than in 2003, the worst year for bay health since the assessments began in 1986. Heavy spring and fall rains washed pollutants and sediments into the bay, and a hot, dry summer spurred algae blooms that lower oxygen levels.