M1 AM Delaware River/Bay
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 1

(LIM-1117-657294) Nutrients in the Lower Non-Tidal Delaware River, 2001-2004: Monitoring Results and Management Recommendations.

Limbeck, R¹, ¹ Delaware River Basin Commission, West Trenton, NJ, USA

ABSTRACT- From 2000 through 2004, the Delaware River Basin Commission's (DRBC) Lower Delaware Monitoring Program (LDMP) conducted a bi-weekly water-quality survey of the Delaware River and selected tributaries located between the Delaware Water Gap and Trenton, NJ. Study objectives included 1) documentation of water quality conditions for the period 2000-2004, and 2) presentation of evidence and advice to the Delaware River Basin Commission in its determination of the Lower Delaware River's suitability for designation as Special Protection Waters (SPW). Objectives of the LDMP are to define existing water quality (EWQ) for this segment of the Delaware River, and subsequently to link long-term water quality monitoring to integrated water management. Nutrient parameters included ammonia, chlorophyll A, nitrate, nitrite, TKN and total phosphorus. Daily dissolved oxygen and pH cycles are strongly affected by primary production at some locations, which may be linked to seasonal nutrient inputs to the river system. Delaware River water quality is generally as good or better than high-quality tributary waters, specifically those designated as High Quality (HQ) and Exceptional Value (EV) waters in Pennsylvania and Category One (C-1) waters in New Jersey. Longitudinal plots and watershed comparisons revealed significant geographic patterns in the nutrient data. Nitrogen and phosphorus concentrations were fairly high but did not render the Lower Delaware unsuitable for aquatic life use. However, the results indicate that the Lower Delaware may be at risk of eutrophication due to excess nutrient inputs. Unknown at this time is what effect increased nutrient levels produce in the Delaware River. Nutrient dynamics must be investigated in the river system, and nutrient criteria must be established. Meanwhile, protection of water quality at existing levels through Special Protection Waters antidegradation rules is recommended.

Key words: delaware river, nutrients, antidegradation, eutrophication