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Annual Report 2023

Annual Report 2023

Flood Protection

Administration

Flood Protection

Achievements

Return of Flood Waters

This year brought the return of rain and floods after several years of drought, with massive storm events in January and March of 2023. Atmospheric rivers drenched the Tri-Valley bringing debris into flood channels, creating blockages in culverts, damaging roads, and making some impassable. The flood events required emergency response from Zone 7 teams to keep our flood channels flowing and our community safe. All roads damaged by the storm events have now been repaired.

11,000 cubic yards

of debris removed from channels

5,385 linear feet

of access roads repaired in response to floods

8,368 cubic yards

of sediment removed

$2,139,809

in clean up and debris removal costs submitted to FEMA for reimbursement

The sediment catch basin in Livermore had exceeded the capacity and was blocking drainage to surrounding neighborhoods. The Flood Maintenance team was able to coordinate with DWR and the city of Livermore to shut off the groundwater recharge for 21 days to complete work in the Arroyo Mocho. The Flood Maintenance team submitted all records to the Federal Emergency Management Agency for a potential 75% cost reimbursement, as part of our responsible fiscal management strategy.

Proactive Flood Maintenance

The department also managed regular proactive maintenance including repairing access road cracking to help prevent future bank failures, removing hazardous encampment debris, and addressing fence damages primarily caused by unauthorized entry.

  • Trash capture devices installed in Dublin in an effort to capture trash before it enters the flood channel.
  • The first annual flood system condition assessment report was completed to evaluate the overall condition of the flood channels and identify any deficiencies affecting flood water conveyance.

2,000 linear feet

of access road cracking repaired proactively

110 cubic yards

of encampment debris removed

47,472 linear feet

of vegetation removed

80

fence repairs

Here we
goat again…

The Zone 7 goats were back for a third season as part of our comprehensive mowing efforts to maintain local flood channels and reduce the risk of fire. The goats eat away overgrown vegetation adjacent to the flood channels with their 6 ft reach, as well as along the ground to control brush and create an effective fire break. The goats naturally clear low lying brush and fallen branches, all without disturbing the soil or using pesticides.

Goats eating away overgrown vegetation adjacent to the flood channels.

The goats hungrily chew away overgrowth of:

Trees

Trees

Bushes

Grasses

Weeds

Shrubs

Ragweed

Poison Oak

Thistles

Thorny Vines

Blackberry

These goats are part of our integrated vegetation management plan with diverse methods of controlling growth alongside flood protection channels, which may double as recreational trails through local partnerships. While these trails provide community benefits, they also pose a high risk for fire, making vegetation management critical – and why we appreciate our goat helpers so much!

Zone 7 collaborates with fire officials, environmental regulators, and wildlife experts to balance fire mitigation with habitat creation in the channels. Mowers are used in the channels from the top of the banks to approximately 8-10 ft into the channel to minimize fire hazards. Then the goats, who are agile climbers, come in and finish up the job as they easily make their way up and down the slopes of the channels, getting to places where the mowers or staff can’t safely access.

Flood Protection Capital
Project Updates

Arroyo Mocho Medeiros Reach Floodplain Reconnection Project

The original project aimed to reconnect the Arroyo Mocho with its natural floodplain in the Oak Grove Nature Reserve. The plan was to excavate the reserve to allow flooding during storms, however, due to public concerns, the plan was revised to minimize disturbances.

  • Project Highlights
  • The project received a $500,000 grant through the California River Parkways Program to improve the trail along the reach of Arroyo Mocho
  • A portion of the asphalt trail was lowered to allow flooding during large storms
  • The Oak Grove Nature Reserve was graded to define trail paths
  • Primary trail work was completed in October 2022
  • Tree planting and invasive species removal continued through October 2023
  • The area is designed to accommodate a 10-year or greater storm event flow

Overall, the project successfully reconnected the Arroyo Mocho River with its floodplain, reducing flood risk and improving the trail.

Zone 7 Water Agency – Annual Report 2023

Zone 7 Water Agency – Annual Report 2023