CAMBRIDGE, Md. (AP) — The Chesapeake Bay’s health dropped for the first time in four years, according to a new report card.

The University of Maryland Center for Environmental Science gave the bay’s health a score of 42 out of 100 possible points in 2010, down from 46 the year before. The upper bay had the highest score at 57 and the lower western shore the lowest at 13.

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The center says two winter storms last year are believed to have led to increased sediments and nutrients entering the bay.

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Nutrients such as nitrogen and phosphorus from sewage, lawns and farms cause algae blooms that rob bay waters of oxygen. Sediments cloud the water and bury bay grasses that provide habitat and help water quality.

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