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Water Science & Technology—WST Vol 59 No 1 pp 9–14 © IWA Publishing 2009 doi:10.2166/wst.2009.739

Investigation of river eutrophication as part of a low dissolved oxygen total maximum daily load implementation

William Stringfellow, Joel Herr, Gary Litton, Mark Brunell, Sharon Borglin, Jeremy Hanlon, Carl Chen, Justin Graham, Remie Burks, Randy Dahlgren, Carol Kendall, Russ Brown and Nigel Quinn

Environmental Engineering Research Program, University of the Pacific, School of Engineering & Computer Sciences, Sears Hall, 3601 Pacific Ave, Stockton, CA, 95211, USA E-mail: wstringfellow@lbl.gov
Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Systech Engineering, Inc., 3180 Crow Canyon Place, San Ramon, CA, 94583, USA
Department of Land, Air and Water Resources, University of California, Davis, CA, 95616, USA
U.S. Geological Survey, MS 434, Menlo Park, CA, 94025, USA
Jones & Stokes, 2600 V Street, Sacramento, CA, 95818, USA


ABSTRACT

In the United States, environmentally impaired rivers are subject to regulation under total maximum daily load (TMDL) regulations that specify watershed wide water quality standards. In California, the setting of TMDL standards is accompanied by the development of scientific and management plans directed at achieving specific water quality objectives. The San Joaquin River (SJR) in the Central Valley of California now has a TMDL for dissolved oxygen (DO). Low DO conditions in the SJR are caused in part by excessive phytoplankton growth (eutrophication) in the shallow, upstream portion of the river that create oxygen demand in the deeper estuary. This paper reports on scientific studies that were conducted to develop a mass balance on nutrients and phytoplankton in the SJR. A mass balance model was developed using WARMF, a model specifically designed for use in TMDL management applications. It was demonstrated that phytoplankton biomass accumulates rapidly in a 88 km reach where plankton from small, slow moving tributaries are diluted and combined with fresh nutrient inputs in faster moving water. The SJR-WARMF model was demonstrated to accurately predict phytoplankton growth in the SJR. Model results suggest that modest reductions in nutrients alone will not limit algal biomass accumulation, but that combined strategies of nutrient reduction and algal control in tributaries may have benefit. The SJR-WARMF model provides stakeholders a practical, scientific tool for setting remediation priorities on a watershed scale.

Keywords: algae; central valley; dissolved oxygen; eutrophication; lowland river; phytoplankton; TMDL


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