An Organic Matter Budget for an Impacted Urban Stream

Previous studies have characterized source and transport dynamics of organic matter (OM) through streams in undisturbed watersheds (Fisher and Likens 1973; Fisher 1977); however, these dynamics in urban streams have not been explored. We present an OM budget for the Jordan River, UT, a mid-sized river that flows through an urban area home to roughly 2 million people. Downstream of a flood protection diversion the water quality of the river is impaired, with dissolved oxygen (DO) as the pollutant of concern. We measured the transport of dissolved (DOM), fine particulate (FPOM) and coarse particulate (CPOM) organic matter, the standing stock of benthic organic matter, and stream metabolism through six river segments (three above and three below the diversion) to generate an understanding of OM transport, processing and storage. The greatest increases of DOM and FPOM were in two specific segments upstream of the diversion, both of which receive wastewater effluent. CPOM transport was insignificant compared to DOC and FPOM. Preliminary budgeting suggests that autochthonous production; in addition to DOM and FPOM from effluent upstream of the diversion are important contributors of problematic OM to the Jordan River