Foster City Levee Improvement Project, O'Neill Slough Restoration

Status Planning County San Mateo
Project Type Compensatory mitigation Location 37.53416° N, -122.26909° W Map
Project Area (Acres) 4.60 Last Updated 20 May 2021
Project Abstract Restore O'Neill Slough from muted tidal to full tidal wetlands by replacing the levee on each side of O'Neill Slough with two free spanning bridges, and purchase 0.1 acre of mitigation bank credits. Purpose of this project is to offset temporary and permanent impacts associated with the levee maintenance project.
Administrative Region San Francisco Bay Regional Water Quality Control Board - Xavier Fernandez, SFBRWQCB

Project Identification

2018.005.00.00 BCDC - Permit Number
WCRO-2018-00327 NMFS - Biological Opinion/Take Permit
851477 SWRCB - 401 Certification Letter (e.g., Site Number or WDID)
2015-00391S USACE - Standard Individual Permit
08FBDT00-2019 USFWS - Biological Opinion/Take Permit

Habitat Plan

Site NamePhaseActivitySubActivitiesHabitatSubHabitatAcresActivity StatusWater Regime
FC Levee O'Neill Slough None Restoration/Re-establishment Unspecified Estuarine Wetland Mudflat 4.50 Construction planned Fully tidal
FC Levee SF Bay Mitigation Bank None Unknown/Unspecified Estuarine Wetland Marsh < 0.1 Completed Fully tidal
FC Levee SF Bay Mitigation Bank None Unknown/Unspecified Estuarine Wetland Mudflat < 0.1 Completed Fully tidal

Related Habitat Impacts

Impact Project NameHabitatAcres LostType of Loss
Foster City Levee Improvement Project (CIP-301-657) Depressional Wetland < 0.1 Lost Permanent
Foster City Levee Improvement Project (CIP-301-657) Estuarine Wetland < 0.1 Lost Permanent


FC Levee O'Neill Slough Construction planned 4.50


DateTypeDescriptionSite Name
2019-08-28 Project start date Estimated date


Contact Robert Perrera Huffman-Broadway Group, Inc. Environmental Consultant


None Unknown/Unspecified City of Foster City $170,000

Related CRAM Assessments

Visit DateVersionSite NameWetland TypeIndex Score
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How to Use the Habitat Development Curve

Habitat Development Curves (HDCs) are used to determine the developmental status and trajectory of on-the-ground projects to create, restore, or enhance California wetland and stream habitats. Each HDC is based on assessments of habitat condition for different age areas of one habitat type that in aggregate represent the full spectrum of habitat development. The assessments of condition are provided by expert applications of the California Rapid Assessment Method (CRAM). Visit the CRAM website for more information about CRAM.

For each HDC, reference condition is represented by areas of a habitat that consistently get very high CRAM scores, have not been subject to disruptive management practices, and exist within landscapes that are protected and managed for their natural conditions. The horizontal lines intersecting the top of an HDC represent the mean CRAM score and standard deviation of scores for 25 qualifying reference areas.

The age of a project is estimated as the elapsed time in years between the groundwork end date for the project and the date of the CRAM assessment. To add or update a groundwork end date, use the Project Events form in Project Tracker ( The minimum age in years of a non-project area, including any natural reference area, is estimated from all available local information, including historical maps and imagery, historical written accounts, and place-specific scientific studies of habitat development.

An HDC can be used to address the following questions:

  1. At what time in the future will the area of assessed habitat achieve the reference condition or other milestones in habitat development? The HDC can answer this question if the CRAM score for the assessed area is within the confidence interval of the HDC. The answer is the time in years along the HDC between the current age of the assessed area and the future date corresponding to the intersection of the HDC and the reference condition or other milestone.
  2. Is the area of assessed habitat likely to develop faster, slower, or at the same pace as most other areas of the same habitat type? The habitat area is likely to develop faster, slower, or at the same pace if the CRAM score for the area is above, below, or within the confidence interval of the HDC, respectively.
  3. What can be done to improve the condition of the habitat area or to increase its rate of development? HDCs by themselves cannot answer this question. Possible answers can be inferred by the following analysis that involves HDCs:
    1. Examine the HDC for each of the four CRAM Attributes;
    2. Identify the Attribute(s) scoring below the HDC;
    3. For any low-scoring Attribute, examine the component Metric Scores (note: the Metric Scores for any public CRAM assessment in the CRAM database can be obtained through EcoAtlas);
    4. Assume the low score of an Attribute is due to its low-scoring Metric(s);
    5. Consider modifying the design or management of the habitat area in ways that will sustainably increase its score(s) for the low-scoring Metric(s).

For more information about CRAM Attributes and Metrics, including their scientific rationale, see the CRAM Manual.

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CRAM Site Scores