The Paradise Cut Expansion Project seeks to decrease peak flows during potential flood events and improve and enhance habitat. Paradise Cut was constructed as a bypass for high flows on the San Joaquin River. At the head of the Cut a rock weir allows San Joaquin flows to enter the Cut when the River is flowing at about 17,000 cfs. Although the channel capacity of the Cut has degraded slightly over the years, it still functions to bypass a portion of high flows. However, as we saw during the 1997 floods, Paradise Cut is not capable of preventing flooding under extreme condition such as occurred in 1997.
The proposed Project is investigating how lands along the San Joaquin River (above the Paradise Cut Weir) can be used as an overflow area to siphon off the peak flows and then safely and more slowly releases those flows back into Paradise Cut. Initial modeling indicates that under a 1997 event, stage is reduced on the San Joaquin River from Vernalis down to Stockton, with the greatest reduction near Mossdale of over 2 feet. Such a decrease would inure substantial benefit to areas which were flooded or at risk of flooding during 1997.
The habitat portion of the Project will increase riverine habitat, especially for endangered species as well as provide protected habitat on the land for terrestrial species such as Swainson’s Hawk and the riparian brush rabbit. The habitat would not be at the expense of existing agricultural uses as the overflow lands would be under an easement to allow most kinds of farming. There is no proposal to condemn land as the currently identified overflow land’s owners are agreeable to negotiating the easement.
So far the studies have been funded by grants from the California Delta Conservancy and funds from RD 2062. Currently the effort is being led by the San Joaquin County Resource Conservation District, American Rivers, and the South Delta Water Agency.
Of course, rerouting high flows from the San Joaquin into Paradise Cut (and downstream thereof) raise the issue of transferring risk from one area to another and mitigation is required. Public outreach efforts (which is ongoing and will continue) include comments such as these and also reveal that downstream support for the project would be conditioned on substantial dredging of the degraded southern Delta channels. As a result of these comments, the involved parties anticipate expanding the current project to include a Delta dredging program to reestablish channel capacities and provide maintenance thereof. Any such dredging component would of course include additional habitat projects and be done in close coordination with the local Reclamation Districts and be consistent with their various levee improvement plans and projects.
For more information on the dredging project proposal see the section on this SDWA website.
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