Water Quality Trends (1970 to 2005) Along Delaware Streams in the Delaware and Chesapeake Bay Watersheds, USA

摘要: Water quality trends from 1970 to 2005 were defined along 30 Delaware streams in the and Chesapeake Bay watersheds USA. improved or was constant at 69% of stations since 1990 80% 1970/1980. Dissolved oxygen (DO) 73% 32% Total suspended sediment 75% 100% Enterococcus bacteria remained 93% Kjeldahl nitrogen 48% phosphorus 66% 85% During 2001–2005, median levels good fair for DO, 78% sediment, 50% bacteria, 59% nitrogen, 56% phosphorus. Good water correlates with high amounts forest area (>25%) watersheds. Since Federal Clean Act Amendments 1970s, improving (50) outnumbered degrading (23) by a 2:1 margin. 1990, (46) exceeded (38) mostly due deteriorating half streams, reversal early gains achieved 1970s. Over last three decades, watershed strategies have preserved streams; however, greater emphasis is needed curb recently resurging increases levels.