addressing climate change adaptation in regional transportation plans

Bay-Delta RegionCounties: Contra Costa, Sacramento, San Joaquin, Solano, and YoloFive Largest Cities (CDOF, 2011): Sacramento (469,566); Stockton(293,515); Elk Grove (154,594); Vallejo (116,508); Fairfield (104, 815)Total 2010 PopulationBay-DeltaRegion3,638,618Contra Costa 1,049,025Sacramento 1,418,788San Joaquin 685,306Solano 413,344Yolo 72,155[U.S. Census Bureau, 2010]Among the APG regions, the Bay-Delta region is unique in that it overlaps withtwo other regions: Bay Area and Northern Central Valley. The Bay-Delta isincluded as a distinct region because of the distinct challenges faced by the areaand the critical importance it plays in statewide water supply. While the Bay-Delta region contains diverse and vulnerable aquatic ecosystems, the discussionof this region focuses specifically on water management..While the Bay-Delta region contains diverse and vulnerable aquatic ecosystems,the content of this region focuses specifically on water management. The statewater system (Central Valley Project and State Water Project) relies on the Deltafor water export from the North to the South. In its entirety, the Delta is hometo over a half a million people, yet more than 23 million people rely on waterthat travels through the Delta, and one sixth of all irrigable land in the UnitedStates is in the Delta watershed (PPI, 2007). Any community reliant on waterthat travels through the Delta must understand how climate change alters thevulnerability of this supply. This section is intended to provide an overview of thelevee system that protects residents, Bay-Delta agriculture, and the water supplyof much of the state.Prior to the 1850s, the Delta was a vast wetland of channels and islandsnourished by semi-annual flooding and sediment deposits. With flood controland land conversion to agriculture, the elevation of large portions of the Deltadropped below sea level. Levees were constructed to protect the agricultural andresidential areas, which are now below-sea-level islands. The lower Delta islandsare continuously dropping in elevation, below sea level, because of topsoil lossfrom agricultural activities, increase in temperatures causing organic soils to dryout, and potential wind storm severity. These factors could result in lower islandPAGE 47APG: UNDERSTANDING REGIONAL CHARACTERISTICS