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Mudflat Augmentation

Mudflat Illustration

Type of Development





Long Term


Natural Habitat




Dependent on scale and availability of fill.


Mudflat augmentation is the intentional placement of fine silts and clays to elevate mudflats relative to rising tides, and can include indirect placement of silts (through reestablishing the watershed connectivity) or direct placement (physical placement of dredged sediment from Bay). Mudflat augmentation decreases sea level rise impacts, reduces storm surges, and restores endangered habitats. Indirect mudflat augmentation requires reconnecting mudflats to tidal marshes and the baylands to the greater watershed. This generates natural sediment flows and a natural increase in elevation over time. Directly placing pre-dredged material from the Bay, which is already nutrient rich, into the mudflat would slowly raise the elevation, over an extended period of time. Restoration of the watershed leads to greater overall health of the mudflats and Bay.

Illustration of shoreline ecosystem that supports biodiversity, groundwater recharge and cooling impacts.


Mudflat augmentation elevates land which decreases sea level rise and storm surge impacts, encouraging sediment and nutrient flow to restore habitats.


Increasing mudflat elevation in relation to tides will protect adjacent infrastructure and habitats by dissipating wave energy and limiting the wave volume that is reaching shores. Therefore, tidal marsh erosion is limited, further protecting the adjacent habitat and infrastructure. Reintroducing natural sediment supply will encourage healthier ecosystems by creating a nutrient rich environmental refuge for burrowing organisms, microalgae, and biofilm. Additionally, healthy ecosystems are more resistant to erosion. The build up of silt and sediment after floods can be channeled to the mudflats when connected to other hydrological systems. Furthermore, mudflats offer a vital habitat for shorebirds, wading birds, and ducks.


Hydrologic System connection, fill availability

Development Considerations

Hydraulic connections will determine the sediment and water supply. Land ownership is important to keep in mind when finding sites.

Environmental Considerations

Aquatic organisms and shallow water habitats should be considered in the filling process. Understanding the kind of silt and clay that is naturally captured in mudflats is important to the restoration.

Maintenance Consideration

Without reconnection to the greater watershed, there is a need to continue a sediment supply until the ecosystem can sustain itself. While other maintenance is not required, tracking the progress of restored mudflats is valuable for future projects. Little to no maintenance is expected after 2 years.

Cost Considerations

Dependent on scale and availability of fill.

Case Studies

Cover of the Moffett Park Specific Plan Urban Ecology Report

Moffett Park Specific Plan Urban Ecology

The Moffett Park Technical Plan lays out a city wide redevelopment of green infrastructure and Nature-Based Strategies that create habitats and natural corridors in order to reduce climate impacts and positively impact the community.

Image of wetland area looking out towards water.

Bel Marin Key Wetlands Restoration

The Bel Marin Key Restoration Project is designed to enhance and create seasonal wetlands, reestablish healthy ecosystems while protecting endangered species, and mitigate effects from the changing climate.

Ground level image of mudflat areas and marshy bank.

Seal Beach Sediment Augmentation Project

Seal Beach, in Southern California, is a pilot project that consists of the addition of a thin-layer (8-10 inches) of clean dredged sediments to 10 acres of a low elevation salt marsh within the Seal Beach National Wildlife Refuge in Orange County, CA in order to increase habitat health and address sea level rise.

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