CRB’s New Water Infrastructure Tool
By Britnee Pannell
The new California Water Infrastructure and Hazards dashboard shows the status of dams, levees, canals, and aqueducts throughout California as well as by each county and Assembly and Senate district and shows the estimated risk of sea level rise to coastal communities as a result of climate change. The California Research Bureau at the California State Library developed the dashboard in response to a legislative request and it is shared with permission from the office. For questions, please email crb@library.ca.gov.
We have included several observations made while using this tool and invite California policymakers and their staff to seek more in-depth answers on the questions raised, or to find inspiration for new applications for these tools that will support the Governor and the Legislature in developing better public policy for the people of California.
Dams
Perhaps surprisingly, Los Angeles County has the most dams (91) of any county in state. Sonoma (63), Napa (57), San Diego (53,) and El Dorado (50) round out the Top five. Despite what the county numbers might suggest, most dams are in the Sierra Nevada range in north-east California, but are dispersed among its numerous, smaller counties.
The legislative district data reflects this. Assembly District 1, the state’s north-east corner, spanning all or part of nine mountainous counties, has the most of any legislative district (303). Despite its larger area and substantial overlap with AD 1, SD 1 (271) ranks second, just ahead of SD 4 (239), which includes dam-dense Amador and El Dorado counties.
Policymakers can use the tool to identify the dams in their districts, including information on the condition of dams and the downstream risk they pose.
Sea Level Rise Exposure
If sea levels rise 6 feet, the entire state of California stands to lose most of its coastal beaches. The low-lying lagoon areas of Humbolt County (AD 2 & SD 2) are also particularly at risk to ocean rise, as are communities near Watsonville and Castroville in the Monterey Bay (AD 29 and 30, and SD 17). Naval bases Port Hueneme and Point Mugu in Ventura County will also have to contend with sea level rise as will the Port of Los Angeles and the Port of San Diego.
Solano County (15.4%) and the regions of AD 21 (39.4%) and SD 10 (22.4%) stand to lose the most land area if sea level rises by 6 feet.
Coastal policymakers can use this information to identify areas that are most at risk to changes in sea level and prepare for the future.
Canals, Aqueducts and Levees
To provide water to its citizens, agriculture and businesses, California has 293 canals and aqueducts covering 4,191 miles. These structures serve to bring water from the wetter northern regions of the state to the more arid climates of the south. In one case, such as with the Colorado River Aqueduct, water is brought in from out of state to provide water to large southern cities such as Los Angeles and San Diego.
Most of these canals travel through the 16 counties that make up the Central Valley: Tehama, Glenn, Butte, Colusa, Sutter, Yolo, Sacramento, Solano, San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and Bakersfield.
In addition, most of the levees in the state are in the Sacramento-San Joaquin Delta region of Sacramento, Solano, Yolo, San Joaquin, and Contra Costa counties. This region is historically prone to flooding, as reflected in the numerous levee breaks recorded in the region.
Background
The Department of Water Resources (DWR) keeps extensive records on the status of the various hydrological infrastructures, as well as documentation on what they look for during their inspections of such devices. As required by California Water Code section 6103, the responsibility for the evaluation of dams falls under the authority of DWR’s Department of Safety of Dams (DSOD). DSOD provides information on its inspection and reevaluation protocols online. According to DSOD’s protocols, the division performs annual maintenance inspections on all jurisdictional dams, and reevaluates dams based on risk.
From page 3 of DSOD’s inspection and reevaluation protocols: “DSOD uses a qualitative approach to risk to prioritize its 1,250 jurisdictional dams and their appurtenances as part of the reevaluation process. Risk is used to guide the decision-making process regarding the safe and continued operation of those dams inspected and evaluated with respect to dam safety. Using risk, as employed by DSOD, is based on detailed reviews and results of geological and engineering evaluations, which are then used for an informed assessment of the probability and likelihood of an event and failure in conjunction with the downstream hazard potential.” The current status of each of California’s dams, as well as the downstream hazard potential should the dam fail, is presented in the dashboard as well as available in report form from DSOD.
In 2006, Proposition 84 established the Local Levee Assistance Program. This program was allocated over $83 million to provide financial assistance to local flood management agencies to repair or maintain their levee accreditation by the Federal Emergency Management Agency (FEMA).
Sea level rise predictions are provided by NOAA in its report “Global and Regional Sea Level Rise Scenarios for the United States: Updated Mean Projections and Extreme Water Level Probabilities Along U.S. Coastlines.” For the California coast and San Francisco Bay Area, the sea level is expected to rise about 1.5 feet by the year 2060. In addition, it is expected that high tide related flooding will add another 1–2 feet of water to this depth. Adding wind and wave driven storm surges results in a flood risk for regions susceptible to the 6-foot rise in sea level portrayed on the dashboard. If the global temperature exceeds an increase in 2℃, the flood risk increases and thus the 10-foot sea level rise effect zone was added to the dashboard.