Application of an Estuary Model to Quantify Factors Contributing to Low Dissolved Oxygen Conditions in the San Joaquin River Deep Water Ship Channel
Bay-Delta Science Conference
October 28-30, 2014
Date of Presentation
The Stockton Deep Water Ship Channel (DWSC), located in the San Joaquin River estuary, has had seasonal and episodic low dissolved oxygen (DO) concentrations for decades. The occurrence of low DO causes the assimilative capacity of the river to be exceeded, impacting ecosystem health and the quality of water supplies that are designated for various uses. To address this impairment, a DO total maximum daily load project was initiated to quantitatively identify the causes of low DO and develop restoration strategies. Here, a one‐dimensional link‐node model was used to simulate water quality conditions in the DWSC. The model was calibrated and validated using six years of data that reflects both wet and dry conditions in the San Joaquin River Basin. Model simulations were run to determine the effect of four factors influencing low DO conditions in the DWSC: elimination of the deepened ship channel, elimination of import of oxygen‐consuming substances (ODS) from the San Joaquin River watershed, elimination of import of ODS from the urban tributaries, and elimination of discharge of ODS from the regional wastewater treatment plant. The model results suggest that the deepening of the ship channel has had the largest impact on low DO conditions, followed by ODS from the agricultural watershed. Since the Stockton wastewater treatment plant was upgraded in the 2007, the impact of ODS from this facility has been significantly reduced. The estimated impact of stormwater from the City of Stockton appears much smaller than the other factors. The study results are useful for assigning responsibility for low DO conditions in the DWSC and for formulating effective restoration strategies. The study results also suggest that removal or elimination of any single variable would not result in a complete resolution of low DO events.
Camarillo, M. K.,
Stringfellow, W. T.
Application of an Estuary Model to Quantify Factors Contributing to Low Dissolved Oxygen Conditions in the San Joaquin River Deep Water Ship Channel.
Paper presented at Bay-Delta Science Conference in Sacramento, CA.