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

Water Science and Technology
By: , and 

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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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Investigation of river eutrophication as part of a low dissolved oxygen total maximum daily load implementation
Series title Water Science and Technology
DOI 10.2166/wst.2009.739
Volume 59
Issue 1
Year Published 2009
Language English
Publisher IWA
Contributing office(s) Toxic Substances Hydrology Program
Description 6 p.
First page 9
Last page 14