There may be possibilities of creating new or enlarged flood bypasses on portions of the Sacramento system. Any comprehensive study of the system should investigate such possibilities. However, because the present system of bypasses already takes advantage of most of the preexisting natural overflow basins along the Sacramento River, enlarging existing bypasses, rather than creating new ones, is more likely to be economically, financially, and politically feasible. There are probably a number of selected areas along the Sacramento River and tributaries where levee setbacks would be feasible to increase the flow area. These need to be examined in a systematic way.
Levee setbacks have other advantages too.
They increase the meander zone available for the low-flow channel of the river, reducing the need for bank protection to protect the levees from being undermined by erosion. Through both planting activities and natural processes, this wider meander zone provides opportunities for improving riparian habitat along river corridors. Finally, the setbacks provide opportunity to construct new levees according to modern day standards of design and construction. Many existing levees were constructed more than a hundred years ago, over a period of decades, using poorly compacted dredge fill and little, if any, foundation improvement. In spite of the advantages of setback levees, they are not a panacea.