San Joaquin River DOTMDL -- Technical Working Group

Stockton Deep Water Ship Channel Tracer Injection Study - Final Report

Authors: Randy Bowersox, Bill Fleenor, Greg Schladow
Publication Date: January 10, 2001
Summary: In an attempt to better understand the water situation in and around Lake
McLeod, it was determined that a tracer injection study would help to highlight some of
the movement and transport properties of the channel. During the course of this study,
two tracer injections were performed. The first injection took place on 7/27/00 and
involved adding less than 1.5 L of 20% rhodamine-WT into Lake McLeod. This amount
was selected to assure that EPA guidelines of 100 ppb would not be exceeded. The
rhodamine was followed throughout the day, but was below detection levels within 24
hours. From the data collected it was learned that water enters Lake McCleod from the
bottom of the channel and leaves from the surface.

A second injection took place on 9/14/00. Based on the findings from the
previous injection, approximately 15 times as much rhodamine was added to the
channel. Due to the amount of mixing and transport that had been observed during the
first injection, it was concluded that this concentrated quantity of rhodamine would drop
to levels under the EPA recommended level of 100 ppb within 4 hours of the injection,
but still leave a large enough mass of tracer to be able to follow and detect the
movements for a considerable period of time.
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