Bel Marin Keys Phase of the Hamilton Wetlands Restoration
|Sponsoring Agency||Coastal Conservancy|
|Watershed Tributary||Novato Creek|
|Public or private land?||('Public',)|
|Location (lat/lon)||38.07025760046315, -122.5198745727539|
|Location Description||Marin County. East of the City of Novato, betwixt the former Hamilton Airfield and Novato Creek.|
Restore tidal marsh and seasonal wetlands, provide flood protection and reuse treated wastewater.
The project will restore tidal marsh and seasonal wetlands on 1,785 acres of land owned by the Coastal Conservancy; as well as, provide flood protection to the local community. The project will also incorporate treated waste-water from the Novato Sanitary District to restore fresh and brackish marsh on the site.
Part 2 - Detail
The project will improve water quality in San Pablo Bay by removing a source of waste-water that is discharged offshore during the wet season. Instead, the waste-water would be used beneficially for marsh habitat along the newly constructed shoreline. The waste-water is currently applied to spray-fields located between Highway 37 and Novato Creek in the dry season. The project would change to a year-round diversion of which would have the added benefit of freeing the spray fields for other public uses (they are owned by Marin County). The ecosystem of San Pablo Bay would benefit from a major increase in the increase of new tidal marsh, mudflats and shallow [sub] tidal habitat - which would total over 1,400 acres. The Bel Marin Keys community, a 700- home residential development will benefit from a new flood protection levee that would be integrated into the wetland design.
Description of Qualitative Benefits : For water quality, it is assumed that a sizable increase in tidal marsh will lead to improved water quality and enhance the beneficial uses of San Pablo Bay, for example recreational fishing. The restored site would have full tidal action over 1500 acres of marsh which would have benefits for the aquatic ecosystem. In terms of restoration, the project will directly benefit dozens of fish and bird species, including several that are threatened and endangered. Though the site is open to the public, it is not managed as a park or open space and is a partially active hay farm. The restoration project would enhance recreation and public access by providing a higher quality environment (seasonal and tidal marsh) and will result in 0.7 miles of public trail along the margin of the site. Types of recreation anticipated include hiking and bird watching, non-motorized boating, fishing, waterfowl hunting. The project will include a new flood management levee which will separate tidal and non-tidal areas. The new levee would be built to a higher elevation than the existing perimeter levee and so is expected to provide a higher level of flood protection to the neighboring residential community.
The project will be constructed in phases. Each phase will comprise some 500 to 600 acres of tidal marsh. Some volume of dredged material will be placed in the [future] tidal portion of each phase and when the phase is complete, the outboard levee will be breached, thereby providing immediate benefits to that phase. Dredged material will be placed against the new flood management levee to create a low gradient fill or 'bench' which will lead to immediate growth of marsh vegetation.
General Information: www.hamiltonwetlands.scc.ca.gov
Project Documents can be found at: http://hamiltonwetlands.scc.ca.gov/issues/
San Pablo Bay
The State of California (Coastal Conservancy) will continue to incur expenses of levee upkeep and property management in order to protect the Bel Marin Keys community from flooding. The effluent from the Novato Sanitary District will continue to be discharged into San Pablo Bay with no added benefit to the environment. The State's investment in the Bel Marin Keys property (over $16 million) for fish and wildlife habitat enhancement and protection will not be realized.
Endangered and other listed bird and fish species in San Pablo Bay will continue to struggle to recover a viable population due to a lack of suitable habitat.
Novato's waste-water, which is treated to a high standard, will continue to be discharged into the Bay in the wet season with no added benefit to the environment.
i. Water Supply (conservation, recycled water, groundwater recharge, surface storage, etc.)
ii. Water Quality:
Project will restore over 1,500 acres of tidal wetlands which will improve the water quality of San Pablo Bay (Beneficial Uses). Also see Section iv below. The project would also beneficially use treated waste-water from the Novato Sanitary District, changing discharge from a wet-season bay discharge to a year-around recycling to restore fresh / brackish marsh on site.
iii. Flood and Stormwater Management
iv. Resource Stewardship (watershed management, habitat protection and restoration, recreation, open space, etc.)
Restoring the BMKV Expansion site would result in approximately 1,785 acres of tidal wetlands, seasonal, and upland habitat for fish and wildlife. Special status species that may benefit from the restoration of BMK include salmonids, salt marsh harvest mouse, California clapper rail, double-crested cormorant, California brown pelican, white-tailed kite, northern harrier, golden eagle, Cooper’s hawk, sharp-shined shooter, peregrine falcon, California black rail, short-eared owl, burrowing owl, salt marsh common yellow throat, and San Pablo song sparrow. Juvenile green sturgeon, and longfin smelt, now listed as an endangered species in the San Francisco Bay Estuary, may also benefit from the restoration project.
Special status species that may benefit from the restoration of BMK include salmonids, salt marsh harvest mouse, California clapper rail, double-crested cormorant, California brown pelican, white-tailed kite, northern harrier, golden eagle, Cooper’s hawk, sharp-shined shooter, peregrine falcon, California black rail, short-eared owl, burrowing owl, salt marsh common yellow throat, and San Pablo song sparrow. Juvenile green sturgeon, and longfin smelt, now listed as an endangered species in the San Francisco Bay Estuary, may also benefit from the restoration project.
Tidal marshes are among the most productive ecosystems in the world. They flourish when the rate of sediment accumulation is equal to or greater than the rate of land subsidence and where there is adequate protection from large waves and storms. Wetlands are areas of high nutrient and biological productivity that provide the detrital products that constitute the base of the food chain. Sediment and epiphytic algae are often important components of the autotrophic community. Heterotrophic communities are often dominated by the detrital food chain of tidal wetlands, providing foraging habitat for several threatened and endangered species. In addition, tidal marshes are out-welling systems that export organic matter to adjacent estuaries.
Tidal marshes provide direct prey resources to several aquatic and terrestrial organisms, including listed juvenile salmonids. Because they are generally rich in invertebrate organisms, tidal wetlands and mudflats that would be created as part of the BMKV restoration project could provide high-value foraging habitat for juvenile salmonids, Shallow tidal wetlands and salt-tolerant vegetation (grasses and rushes) can provide refugia from predators.
Some studies suggest that juvenile salmonids that rear in wetland areas grow
larger and, therefore, may be less prone to predation when they enter the marine
environment. Restored tidal wetlands may also directly benefit other species including starry flounder and English sole, which are known to use tidal wetlands for rearing, and Sacramento splittail, which may use wetland habitat for spawning and rearing.
Tidal wetlands may also indirectly benefit several protected species that do not directly use tidal wetland habitat (e.g., EFH-managed species that inhabit San Pablo Bay). Export of organic detritus from tidal wetlands can increase primary productivity in adjacent estuaries. Detritus that flows to the estuarine waters can sustain prey species for several aquatic organisms and help support secondary production, especially in estuaries where plankton primary production is depressed. Studies suggest that organic detritus, either filtered from the water or ingested from the sediment, is an important alternate source of energy for aquatic organisms, especially when plankton concentrations are low.
Tidal wetlands can act as a buffer against the effects of sea level rise by stabilizing shorelines and creating a buffer against erosion. Tidal wetlands can also sequester carbon and thereby help offset the emission of green house gases. Creation of wetland habitat through implementation of the project would have direct benefits to fisheries and the ecological health of through implementation of the project would have direct benefits to fisheries and the ecological health of SF Bay and adjoining ocean by significantly reducing, if not completely eliminating, dredged material placement in the ocean and bay while BMK is being filled. There will also be benefits to benthic communities located at and near Alcatraz, the other two in-bay sites, and the deep-ocean water column that result from the diversion of dredged material to the ATF and, hence, to the BMK. Once the BMK is returned to tidal action, bay fishes will benefit from the newly-restored wetland habitats by reducing, if not completely eliminating, dredged material placement in the ocean and bay while BMK is being filled. There will also be benefits to benthic communities located at and near Alcatraz, the other two in-bay sites, and the deep-ocean water column that result from the diversion of dredged material to the ATF and, hence, to the BMK. Once the BMK is returned to tidal action, bay fish will benefit from the newly-restored wetland habitats.
Promotion of economic, social, and environmental sustainability
Avoiding, minimizing, and mitigating net impacts to environment: The project will recycle dredged sediment which will otherwise be disposed of into the aquatic environment, either at a Bay disposal site or at the deep ocean disposal site. Disposal of dredged material has negative impacts to the aquatic environment. Transportation of dredged sediment to the ocean disposal site (which is located 50 miles west of the Golden Gate, also results in significant negative impacts to air quality in terms of emitting both diesel exhaust and Carbon Dioxide. Because tidal marshes sequester carbon, the project not only reduces water and air impacts as compared to bay and ocean disposal) but it can partially mitigate for carbon impacts from the dredging and transport of the sediment.
Maintaining and promoting economic and environmental sustainability through sound water resources management practices: The project will result in a long-term solution to dredged sediment disposal which will have a positive impact on the Bay Area maritime economy. Uncertainties related to dredging have hampered ports and marinas for decades. The project will provide a multi-year solution to dredge material disposal. And once filling of the site is complete (5-10 years) the same model can be applied to other sites in the Bay Area and Delta. Restoration of tidal marsh is sustainable because there are tens of thousands of acres available for restoration, because the benefits outweigh the negative impacts and the approach has been proven to be feasible and successful. Reuse of treated waste-water from the Novato Sanitary District will assist the District in managing its operations by providing an essentially indefinite end-use for its waste-water, which in turn helps the District plan for future work.
Providing trails and recreation opportunities: The project will construct an extension to the 2.67-mile Hamilton Bay Trail an approximate length of 0.7 miles. The trail will meet ADA guidelines and will provide a connection between two communities that otherwise are not directly linked.
Creation, protection, enhancement, and maintenance of environmental resources and habitat:
The project will construct a new flood management levee which will help protect the Bel Marin Keys community from flooding and will provide a flood storage volume within the newly established seasonal wetland portion of the project which could improve localized flood risk.
Creation, protection, enhancement, and maintenance of environmental resources and habitats. Providing net benefits to environment: The project will restore wetlands using
dredged sediment will be recycled to be used as fill in order to restore grade
to subsided land. With this project, the
disposal of dredged sediment in San Francisco Bay and the ocean could be
brought down from an annual volume of about 2 million cubic yards to nearly
less than fifty thousand for a decade or more.
This will in turn have a benefit for benthic environment at or near the
designated disposal sites (primarily Alcatraz Island and the Deep Ocean
Disposal Site). Concomitant with a
reduction in ocean disposal, there will be a reduction in air pollution and C02
emissions (from tug traffic), as the ocean disposal site is located some 50 miles
offshore of the Golden Gate and the subject restoration site is less than 10
miles from dredging sites.
Conserving and restoring habitat for species protection; acquiring, protecting and/or restoring wetlands, streams, and riparian areas; Enhancing wildlife populations and biodiversity (species richness) Providing lifecycle support (shelter, reproduction, feeding); protecting and recovering fisheries (natural habitat and harvesting); Protecting wildlife movement/wildlife corridors; Recovering at-risk native and special status species; Securing funds to implement solutions:
The project will convert 1,785 acres of baylands that has been farmed since the late 1800s back into marsh and seasonal wetlands. The end result will be newly created habitat that will benefit migratory waterfowl and resident shore birds. The site is expected to support the endangered California Clapper Rail and state-listed Black Rail, as well as the endangered the salt marsh harvest mouse. The channels and shallow subtidal areas will support numerous bay fish species including the endangered green sturgeon and juvenile salmon. The seasonal wetland and perimeter levees and transition zones will continue to support resident deer, coyote and small mammal populations. The tidal wetland will feature fill placed at varying elevations in order to create “micro- topography” which will, when vegetated, provide high-tide refugia for the SMH mouse and other species. A significant (but yet to be determined) portion of the site will allow fishing and the eastern most portions of the site may allow duck hunting, as regulated by the State Department of Fish and Game. The seasonal wetlands and western extent of the site will provide a wildlife corridor that will allow north-south transit of wildlife between the newly restored Hamilton Airfield and the marshes and diked baylands north of Novato Creek.
The Conservancy purchased the subject property in 2001 for $16,000,000 with a mixture of general fund challenge grant, non-profit contributions, SWRCB Revolving Loan and state bond funding. In addition, at the adjacent Hamilton Airfield, the Conservancy has expended over $20 million to implement the restoration of that property.