The Headwaters IBI data is used in concert with available macroinvertebrate data to assess the status of aquatic life designated use in state waters as required by the CWA section 305(b) 106 (e) (1). These data are used to identify impaired waters under section 303(d) 106 (e) (1). The data help to measure water quality use attainment and the Department's success in attaining the Clean Water Act goal of "fishable" waters as elaborated in the New Jersey Integrated Water Quality Assessment Report.
In New Jersey, headwater streams account for approximately 80% of the total stream miles in northern part of the state; of which 38% of the total stream miles in northern NJ are protected by antidegradation designations policies (Outstanding National Resource Waters (ONRW) or Category One waters by the NJDEP Surface Water Quality Standards. In addition to their abundance, headwaters streams provide important ecological services in providing stream flow, transport of organic matter, storage of nutrients, regulation of sediments, and providing vital habitat that supports biodiversity (Lowe and Liken, 2005; Alexander et al. 2007; Meyer et al. 2007; Wipfli et al. 2007). Headwaters are essential to watershed health because they dictate the downstream water quality; however, due to their small size they are highly vulnerable to anthropogenic disturbances and changes in climate (Lowe and Liken 2005, Brooks 2009). The quality of headwater streams typically deteriorates with increasing anthropogenic stress (land development, altered flow regime, pollution, ect.) and results in measured changes in a stream’s biota. The health of these small streams is measured by the Headwaters Fish Index of Biotic Integrity (HIBI), a multimetric index that assesses the overall condition of a headwater stream based on the biological assemblage present within and along the stream corridor.
Headwaters monitoring began in 2014 to complement the existing northern fish IBI program to assess stream condition, water quality and habitat in high gradient headwater streams (typically Strahler stream orders 1-3) north of the geological fall-line with a drainage area less than 4mi2 (10.4 km2). The HIBI utilizes the assemblage of fish, crayfish, and amphibians present within and along a stream to assess the overall condition of the headwater stream. Taxa other than fish (crayfish, frogs and salamanders) are included in the HIBI because small order streams often have naturally low fish species richness and cannot be accurately assessed with a solely fish based IBI. Fixed sites are sampled on a five year rotating basis, with monitoring focused on one of the State’s five major Water Regions each year.