General tropic state index of PH, SD, TP, TN, BOD, COD and chla suggests that water body of Miyun Reservoir already belongs to middle nutrition and there is the tendency to eutrophicate.

• pH、透明度(SD)、总氮(TN)、总磷(TP)、生化需氧量(BOD)、化学需氧量(COD)、叶绿素a(chla)的营养状态指数综合评价表明，密云水库水体为中营养型，并且出现了向富营养发展的趋势。