These two photo's are looking down stream from the dam at low and high tides
These two photo's are also a good example of why Rainbow Smelt and Tom Cod spawn above the head of tide.
Smelt and Tomcod do not distinguish between high and low tides when spawning. Therefore when they come upstream to spawn at high tide they cast their spawn in areas that become exposed during low tides. Therefore in places like this many of their eggs never have a chance to develop and hatch.
Under natural circumstances these two fish would time their spawning runs to the highest tides in order to get as far above the tide as possible to insure maximum spawning success. Here they cannot do this due to the dam.
Links to Rainbow Smelt and Tom Cod life histories