Unfavorable weather conditions last year worsened water quality in the West and Rhode rivers south of Annapolis, according to the environmental group working to restore them.

The two Chesapeake Bay tributaries earned a 'D' grade overall on the West & Rhode Riverkeeper's annual report card on their health, a drop from 2010 that the group attributed to a wet spring and hot summer worsening water quality conditions.

Although there were no major fish kills reported last year, the report card notes, weather conspired to make conditions worse for crabs and fish, increasing nutrient pollution and algae while lowering dissolved oxygen levels in the water.  Heavier spring rains wash more fertilizer and other nutrients off the land, while hot temperatures help drive down dissolved oxygen levels in the water, stressing fish.

Water clarity remained poor, earning a 'D' grade, and the report card noted that flyover surveys still did not find any robust underwater grass beds in either river.

"While this is not good news, we don’t want to get too discouraged about one particularly bad year," Chris Trumbauer, the West/Rhode Riverkeeper wrote on the report card. "What is discouraging is that extreme weather potentially may be more common, with years like 2011becoming the new “normal.”

The tributaries did earn an 'A' grade for being relatively safe for swimming.  Of 223 water samples taken last year, only 10 had bacteria levels high enough to make the water unfit for human contact, the report card said, the lowest number in five yeras. Still, the riverkeeper cautioned against going in the water within 48 hours of any rain, noting that relatively few of the samples taken last year were after a rainfall.  Rains tend to cause sewer overflows and wash bacteria-laden septic leakage, pet and wildlife waste into waters.