flood control and erosion control in contra costa county streams

Flood Control and Erosion Control in Contra Costa County Streams StormCon WorkshopMay 12, 2006San Ramon, CaliforniaMitch AvalonContra Costa County Flood Control District

I Live in a Watershed

Flood Control District Role/Responsibility/Opportunity

Manage 72 miles of stream channelManage regional detention basinsWatershed-wide planningC-3/HMP regional facilities

The Flood Protection System

Contra Costa County Creek Conditions

Flood Control District Role/Responsibility/Opportunity

Manage 72 miles of stream channelManage regional detention basinsWatershed-wide planningC-3/HMP regional facilities

Changing Strategies

Stormwater connectivity or stormwater retentionArmored channels or natural systemsFloodplain functionLand use changes and re-engineered creeksMaintenance activities

1800Historical Coyote Creek Drainage Network

2005Modern Coyote Creek Drainage Network

Unconfined Groundwater Recharge Basin2005

Las Trampas Creek - 1966

Pinole Creek Flood Control Channel

Pinole Creek Greenway Project Upper Reach

Pinole Creek Greenway Project Lower Reach

Recent and Planned Restoration Projects

Pacheco Marsh Restoration Marsh Creek Reservoir ExpansionStrentzel Creek Meadow RestorationKnightsen BiofilterCanada del Cierbo RestorationSan Ramon Creek Bioengineering Repair

Pacheco Marsh 120 acre Tidal Wetland Restoration

Marsh Creek Reservoir

Marsh Creek Reservoir 218 Acre Expansion

Strentzel Creek Meadow Grading Plan

Strenzel Creek Planting

Downtown Knightsen

Canada del Cierbo Mitigation

Canada del Cierbo Mitigation

Collaboration Collaboration - Collaboration

Watershed Councils/Creek GroupsCities/Municipal Advisory CouncilsNeighborhood groups/property ownersContra Costa Watershed ForumWatershed Atlas

Stormwater Program Role

Coordinated development of HMPStormwater C-3 GuidebookCase Studies/ResearchEducation/Adaptive TrainingStream and Wetlands System Protection Policy

Downtown Walnut Creek - 1958

A New Approach

Historic Design Concept- Protect structures and convey stormwater off as fast as possibleNew Design Concept- Protect structures and retain stormwater as long as possible

Grayson Creek Channel - 1957

A New Approach

Historic Design Concept- Protect structures and convey stormwater off as fast as possibleNew Design Concept- Protect structures and retain stormwater as long as possible

Hydrograph Modification Management

Increase retention timeIncrease stream stabilityHealthy sustainable watershedCumulative improvement

The Impact of Impervious Surfaces

Stream Stability Approach

Historical SystemPresent SystemCompare Past and PresentUnderstand ChangesRecommendations and Restoration Templates

Sustainable WatershedCommunityWater Quality/Quantity(Hydrology)Habitat(Ecology)Creek Stability/Function(Geomorphology)

The Future

At the parcel levelLIDHomeowner educationLandscape contractors

The Future

At the Watershed level2nd generation facilitiesSystem preservation/ replacementClean Water Regional TreatmentRegional retention facilitiesThe 50 year planMarsh Creek Reservoir

Remember you live in a Watershed too..

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