Your WaterFlood and Stream ManagementWatershed and Environment

A More Eco-Friendly Approach to Flood Protection

For the past 40 years, the Valley has relied primarily on channelized arroyos, many of them concrete, to convey stormwaters through the area and out to the Bay as quickly as possible.

 

But the new, more environmentally friendly Stream Management Master Plan's vision over the next three decades is to create a flood-protection program that relies largely on using the future Chain of Lakes, a series of mined-out gravel pits between Livermore and Pleasanton, to detain stormwater in the Valley. The stored water would be released downstream only after storms pass through the area, meaning arroyos can be kept in a more natural state than under the channelization method.

 

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Not only significantly less expensive when it comes to flood control, this technical approach also affords opportunities to:

 

  • improve our water supply through groundwater recharge
  • enhance arroyo water quality and habitat
  • increase the connectivity of trails and recreational opportunities in the Valley
  • promote public understanding of our watershed through educational programs

Of the 45 conceptual projects identified in the SMMP, 10 would remove or modify fish-passage barriers in Arroyo Mocho, Arroyo del Valle and Arroyo de la Laguna. Others would restore natural stream flows, replace plants with native types, stabilize stream banks, create wetlands and other habitat for sensitive species, and install trails and educational kiosks near Valley arroyos. 

SMMP Funding

 

For the flood-protection portion of the SMMP, a development impact fee apportions to new development -- not to existing residents and businesses -- the share of costs of those improvements needed specifically to manage the additional stormwater runoff generated by new development so that development pays its fair share. The share of costs for flood protection unrelated to new development will come from existing users or grants.

For a copy of a adopted Development Impact Fee Ordinance (DIF), which took effect in 2009, click here.

More About the SMMP

In 2011, Zone 7 laid the groundwork for updating its Stream Management Master Plan. The update will address new California Environmental Quality Act (CEQA) requirements for climate change analysis and incorprorate recent watershed-wide changes, including potential steelhead access to the northern part of the Alameda Creek Watershed. This update will also help facilitate any future revisions to the DIF. As part of the SMMP update, Zone 7 staff focused in 2011 on creating, calibrating and running new service area hydrologic and hydraulic models; investigating innovative techniques for stormwater management, including enhancing natural floodplains and vegetated stormwater channels; and applying for grants.

In addition, Zone 7, in partnership with the Urban Creeks Council, was awarded a $190,000 grant in Novemer 2011 from the California State Coastal Conservancy for environmental studies in the watershed to assist in the update of the SMMP and subsequent update of the DIF. The grant provides money to conduct studies of existing bird and fish populations, help guide stream corridor design decisions, and provide Zone 7 with some of the information needed to address climate change in upcoming CEQA analysis, as is now required under state law.

Zone 7 and the City of Livermore have collaborated to integrate the SMMP and the El Charro Specific Plan. In 2011, Zone 7 finalized a $10 million partnership agreement with the City for flood protection improvements within the El Charro Specific Plan Area, and the city completed a majority of the improvements. These improvements are intended to function in conjunction with the regional flood control system. 

To view Zone 7's main page for Flood Protection & Stream Management, click here.

  • To view Zone 7's main page for Flood Protection & Stream Management, click here.
  • For Reports & Planning Documents, click here.
  • In 2014, the addition of new stream gauges to Zone 7's stream gauging network also facilitated real-time flow reporting for the public via the Storm Central website: (https://stormcentral.waterlog.com/public/Zone7).

streamflow-mapZone 7 owns and maintains 37 miles of local flood-protection channels, about a third of all the Valley's channels and creeks. The remaining channels are owned either privately or by other public agencies, which are responsible for repairs and maintenance.  Maps of Zone 7’s flood protection channels are available at the front counter of our administration building, located at 100 North Canyons Parkway in Livermore.

The Valley's flood-protection system begins at city-owned storm drains on local streets. Storm water flows through underground pipelines into creeks or man-made channels feeding into Arroyo Mocho, Arroyo las Positas and Arroyo del Valle. These larger channels converge with Arroyo de la Laguna, which ultimately drains into San Francisco Bay through Alameda Creek. In addition to flood protection, the channels also have recreational benefits and protect natural habitat.

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Channel maintenance: To ensure that its flood-protection channels are ready for the next big storm event, Zone 7 conducts routine maintenance such as inspections, embankment and drain structure repairs, vegetation management, silt removal and pest control.

 

Emergency repairs

Zone 7 also administers an emergency response program that prepares us to act quickly and minimize the loss of life and property should a flood occur. For federally declared storm disasters, Zone 7 may apply for reimbursement from the Federal Emergency Management Agency or the U.S. Army Corps of Engineers.

Our Reliability "Bank Account"

Unlike most other Bay Area communities, the Valley benefits from local water-storage capacity in an underground basin that provides us with increased water-supply reliability.

Operating the basin as a bank account, Zone 7 during wet years uses a portion of its State Water Project water coming through the Bay-Delta, along with local surface runoff water stored in Del Valle Reservoir, to recharge the groundwater basin. This is done via release of water into local streams that then percolates into the underground aquifer. We draw stored water to augment imported water supplies, especially during the summer when seasonal water demands are the highest, and in times of drought. Recharge also helps dilute the natural hardness of groundwater.

50-yrteeshirtback_final3Zone 7 had been in its infancy when the first State Water Project deliveries were made in 1962, and it marked the beginning of sustainable groundwater management locally. Zone 7 initially used all of its early State Water Project deliveries to replenish the groundwater basin that had been over-pumped over the previous decades. Groundwater recharge using imported surface water supplies continued even after Zone 7's treatment plants opened, and has been a critical component of Zone 7's water resources management ever since.

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Regularly monitoring groundwater levels helps Zone 7 protect against overdraft of the Valley's underground storage basin, and ensure its long-term reliabilty as a drinking-water supply. Shown here is monitoring at a Pleasanton wellfield.

Protecting the Groundwater Basin's levels

The Valley's main groundwater basin has an estimated storage capacity of 250,000 acre-feet (an acre-foot is about 326,000 gallons, enough to supply two households per year). To prevent overpumping, the basin is cooperatively managed by Zone 7 and its retailers so that, even during multiyear droughts, groundwater levels do not drop below historic low levels of 130,000 acre-feet.

Protecting the Quality/Reliability of Groundwater Basin Supplies

  • To learn about Zone 7's Salt Management Plan update, click here.
  • For information on our Mocho Groundwater Demineralization Plant, which will reduce the buildup of salts and minerals in our groundwater basin and improve delivered water quality, click here.
  • To view the annual Groundwater Management Program Annual Report, click here.

A Long-Term Asset

wdc_rig.jpgZone 7 is working to boost its surface-water treatment capacity so it can rely less on groundwater to meet demand in normal rainfaill years. Nevertheless, the basin remains a critical component of reliability planning:

  • Through our future Chain of Lakes, created from a series of abandoned gravel quarries between Livermore and Pleasanton, Zone 7 plans to increase groundwater recharge during wet years with imported water supplies.
  • As part of its Well Master Plan, the agency is planning new wells -- two that came on line in the Chain of Lakes area in 2010 -- to ensure sufficient production during surface-water shortages.

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Offsite Groundwater Banking Programs

Zone 7 also has groundwater-banking rights in Kern County, allowing us to store surplus state water supplies during wet years to draw upon when needed during a drought. We have obtained 65,000 acre-feet of groundwater storage capacity in the Semitropic Water Storage District and another 120,000 acre-feet of capacity from the Cawelo Water District.

lake_del_valle.jpgDel Valle Reservoir is used by the State Water Project to store imported water for Zone 7, the Alameda County Water District (serving the Fremont area) and the Santa Clara Valley Water District. In addition, Zone 7 uses a small portion of Del Valle Reservoir capacity to store rain runoff from our local watershed. As with imported water, some of this water is treated and delivered for municipal use and some is used to recharge the local groundwater basin.

The reservoir was completed in 1968, along with Bethany Reservoir, as part of the State Water Project. It was built as a storage facility for the South Bay Aqueduct, but also for flood protection and for recreation. For information on the multiple uses of the reservoir, follow the links below.

The Dam:

  • Structural Height: 235 feet
  • Crest Elevation: 773 feet
  • Crest Length: 880 feet
  • Volume: 4.15 million cubic yards of earth fill

The Reservoir:

  • Storage Capacity: 77,100 acre-feet
  • Normal Storage: 25,000 to 40,000 acre-feet
  • Surface area: 708 acres
  • Shore Line: 16 miles
  • Length: 5 miles
  • Maximum Depth: 153 feet
  • Surrounding Land: Del Valle Regional Park