Didn't Take 'em Long...

[John Sv]

Question:
With all of the water exported south, don't we kinda keep the delta artificially fresh now? Specifically speaking to salmonids, does a saltier delta hurt smolts or can they still use it before heading out?
Thanks

[Darian]

"Question:
With all of the water exported south, don't we kinda keep the delta artificially fresh now? Specifically speaking to salmonids, does a saltier delta hurt smolts or can they still use it before heading out?"

John,.... I'm not sure what keeping the Delta fresh means(??) I guess you could say that fresh water outflow or salt water intrusion freshens the Delta?? At times, when in-river flows are high and tidal activity is low, fresh water pushes the salt water back and when tidal activity is high and in-river flows are low, salt water intrusion occurs. This is overly simplified.

Now comes the artificial part. Add into the equation dams on the San Joaquin River and all of it's tributaries (save one) reducing in-river flows to the point where sections of the San Joaquin run dry during parts of the year and dams on the Sacramento River and it's tributaries each controlling releases into the system, you get artificially median flows over the course of a year (unless drought conditions impact that flow regime as they have recently). All of this creates un-natural in-river flows.

Now add in the CVP/SWP pumps at Tracy. These pumps are so powerful that when they are in operation at capacity, can reverse in-Delta outflows from their natural route. This impacts/confuses the route that migrating Salmon choose to follow into their natal rivers/streams. In the case of the San Joaquin flows are non-existent at critical times blocking migration altogether or polluted with AG insecticides/pesticides when water is available. The current hearings by the State Water Resources Control Board is about increasing flows to address this problem. For other fish species this artificial changing/mixing impacts the spawning habitat of fish like the Delta Smelt and other Delta species. Then there's the problem of predation (big fish eating little fish, etc.) and pelagic organism decline. I'm not even going to try to address the anticipated impact of the proposed Waterfix (tunnels) Project....

This really doesn't answer your question about whether smolts being impacted by a saltier Delta but it's not entirely about whether Salmonids are impacted, to me. It's about whether any/all species (communities, farmers, fish or animal) who live in the Delta are impacted negatively.

All of this stuff should be discussed by someone/organization with more knowledge on the subject than me.

[John Sv]

Thanks for the clarification. I just figured that with the water deliveries occurring for at interest in the late summer, the area around the pumps and the San Joaquin side in general might actually be less salty in summer and fall than was historic. Sounds like that speculation is incorrect.

[Darian]

Well,.... Seems like you're correct about the water around the pumps. Before the dams, flows were very low in the late summer/fall. High flows in winter/spring. After the dams were built, water was diverted, stored and released (managed) for uniform distribution. Ideally, pumping should be carried out when flows are high (in winter) and decrease in volume when flows are low but if allocations are honored, is done year round. Regardless of the time of year, when water is being pumped at CVP/SWP, water near the pumps is less likely to contain saltwater.

IMO, the problem is that pumping alters flow patterns for the entire Delta, bringing in pollution from municipalities, AG activities and saltwater in to areas that don't normally see high levels of contaminants. If tides are high when the pumps are running, it probably requires increased releases from dams to offset the tidal surge. So, it seems that the Delta is a complex system....