SURFACE WATER AND RIPARIAN AREAS OF THE RARITAN RIVER BASIN A Technical Report for the Raritan Basin Watershed Management Project New Jersey Water Supply Authority Final Report: September 2002 II NJ Water Supply Authority SEPTEMBER 2002 SURFACE WATER AND RIPARIAN AREAS OF THE RARITAN RIVER BASIN TABLE OF CONTENTS Acknowledgements .........................................................................................................................................vi Summary .........................................................................................................................................................1 Hydrology ........................................................................................................................................................2 Surface Waters ....................................................................................................................................................... 2 Hydrology and Topography of the Raritan Basin.................................................................................................. 2 Hydrologic Cycle ..................................................................................................................................................... 4 Hierarchy of Streams in Watersheds..................................................................................................................... 4 Headwater Streams and Attributes........................................................................................................................ 5 Surface Flows of the Basin..................................................................................................................................... 6 Changes in Stream Hydrology............................................................................................................................... 11 Stream Channels .................................................................................................................................................... 13 Stream Channel Components ............................................................................................................................... 13 Stream Morphology Classification ......................................................................................................................... 14 High Flow Events.............................................................................................................................................14 Types of Floods ...................................................................................................................................................... 14 Flood Plains............................................................................................................................................................. 15 Definitions................................................................................................................................................................ 15 Benefits of Flood Plains.......................................................................................................................................... 16 Fluvial Versus Tidal Flood Plains........................................................................................................................... 16 Flood Damages ...................................................................................................................................................... 16 Areas of the Basin within 100-Year Flood Prone Areas ....................................................................................... 16 Preventive Measures.............................................................................................................................................. 17 Frequency of High Flows.................................................................................................................................18 Magnitude and Frequency ..................................................................................................................................... 18 History of Floods in the Basin................................................................................................................................. 18 Flooding Due to Hurricane Floyd ........................................................................................................................... 21 Watershed Based Changes in High Flows......................................................................................................22 Effects of Urbanization on Watershed Hydrology................................................................................................. 22 III NJ Water Supply Authority SEPTEMBER 2002 Effects of Sewage Treatment Plants ..................................................................................................................... 23 Imperviousness and Runoff ................................................................................................................................... 23 Increase in Contaminants....................................................................................................................................... 23 Population Projections and Shifts within the Raritan Basin.................................................................................. 24 Ecological Health.............................................................................................................................................24 Surface Waters ....................................................................................................................................................... 24 General Health........................................................................................................................................................ 24 Benthic Macroinvertebrates ................................................................................................................................... 25 Fisheries/Shellfisheries........................................................................................................................................... 34 Eutrophication ......................................................................................................................................................... 37 Wetlands..........................................................................................................................................................38 Functions and Values of Wetlands ........................................................................................................................ 38 Wetlands Within the Raritan Basin ........................................................................................................................ 38 Effects of Urbanization on Wetland Systems........................................................................................................ 40 Riparian Areas.................................................................................................................................................41 Functions and Values of Riparian Areas ............................................................................................................... 41 Extent of Existing Riparian Areas Within the Basin .............................................................................................. 43 Health of Existing Riparian Areas Within the Basin .............................................................................................. 44 Effects of Urbanization on Stream Corridors/Riparian Areas............................................................................... 45 Public Uses......................................................................................................................................................46 Designated Uses Determined by NJDEP Surface Water Classifications ........................................................... 46 Other Recreational Uses in the Basin ................................................................................................................... 54 Management Conclusions of Existing Plans ...................................................................................................55 Existing Laws and Regulations.............................................................................................................................. 55 Model Stream Corridor Ordinances....................................................................................................................... 57 State Development and Redevelopment Plan...................................................................................................... 57 Green Brook Flood Control Project........................................................................................................................ 58 South River Flood Control and Ecosystem Restoration Project .......................................................................... 58 Millstone River Watershed Protection and Flood Damage Reduction (PL-566) Project.................................... 59 United States Army Corps of Engineers Millstone River Watershed Flood Damage Reduction Project .......... 59 Stormwater Watershed Model ............................................................................................................................... 60 South Branch