on abundance and diversity of aquatic organisms such as algae, aquatic plants, benthic macroinvertebrates and fish.  For example, elevated algal concentrations (blooms) are often indicative of excessive nutrient inputs (usually phosphorus and nitrogen) to a water body that result in a eutrophic state.  Also, the occurrence of nuisance algal blooms and excessive aquatic plant growth may be related to environmental stress associated with deteriorated water quality conditions.  Likewise, reduced benthic macroinvertebrate abundance (such as crayfish) and diversity may indicate degraded water quality conditions since these organisms are generally localised and display varying degrees of sensitivity to pollution. The New Jersey Department of Environmental Protection monitors freshwater streams via the Ambient Biomonitoring Network {AMNET}(NJDEP, 2000).  Each stream is rated as non-impaired, moderately impaired, or severely impaired. NJDEP samples over 800 stream sites statewide once every five years.  There are a number of factors that impact streams that have been identified by this program.  Environmental factors that may adversely affect stream biology, including both chemical and physical parameters, are: Lack of dissolved oxygen Higher than normal temperature Excessive turbidity Presence of toxicants Eutrophication Degraded habitat Lack of bank vegetation/canopy Excessive sedimentation Lack of streamflow Other NJDEP reports indicate that aquatic life impairments can generally be attributed to water quality, sediment quality, habitat alterations (for example, erosion, sedimentation), flow alterations (for example flashiness, low or high flows, drought), and natural population shifts.  Habitat degradation can often result when waterways have been modified for flood control, drainage improvement, navigation, and urbanisation.  Some human activities,