Humboldt Bay National Wildlife Refuge - White Slough

Status In-progress County Humboldt
Project Type Non-mitigation Location 40.70372° N, -124.21135° W Map
Project Area (Acres) 37.50 Last Updated 5 April 2022
Project Abstract Not provided
Administrative Region North Coast Regional Water Quality Control Board - Gil Falcone, Kaete King, NCRWQCB

Project Identification

1B15030WNHU SWRCB - 401 Certification Letter (e.g., Site Number or WDID)
813925 SWRCB - CIWQS Place Number

Habitat Plan

Site NamePhaseActivitySubActivitiesHabitatSubHabitatAcresActivity StatusWater Regime
White Slough West Unit None Restoration (unspecified) Vegetation Management Estuarine Wetland Emergent Saline to Brackish Marsh 37.50 Construction in-progress Fully tidal
White Slough West Unit None Restoration (unspecified) Vegetation Management Riverine Wetland Channel No Data Construction in-progress Riparian

Related Habitat Impacts

Impact Project NameHabitatAcres LostType of Loss
No Data


White Slough West Unit Construction in-progress 37.50


DateTypeDescriptionSite Name
2015-01-01 Project start date


Contact Gil Falcone North Coast Regional Water Quality Control Board 401 Unit


No Data

Related CRAM Assessments

Visit DateVersionSite NameWetland TypeIndex Score
2022-07-14 6.1 WhiteSlough-AA4-2022 estuarine perennial saline 73
2022-07-14 6.1 White Slough- AA5-2022 estuarine perennial saline 78
2022-07-14 6.1 WhiteSlough-AA1-2022 estuarine perennial saline 76
2022-07-14 6.1 WhiteSlough-AA2-2022 estuarine perennial saline 71
2022-07-14 6.1 WhiteSlough-AA3-2022 estuarine perennial saline 63
2017-07-09 6.1 WhtSlgh-AA5 estuarine perennial saline 62
2017-07-09 6.1 WhtSlgh-AA1 estuarine perennial saline 65
2017-07-09 6.1 WhtSlgh-AA2 estuarine perennial saline 49
2017-07-09 6.1 WhtSlgh-AA3 estuarine perennial saline 52
2017-07-09 6.1 WhtSlgh-AA4 estuarine perennial saline 48
2007-10-22 5.0.1 Remnant White Slough Marsh-HBNWR estuarine perennial saline 87

Performance Criteria

StatusDetailsEvaluation Date
Original criteria See Restoration and Monitoring Reporting Plan 2015-01-01

No files found.

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.

Display Habitat Development Curves For Wetland Type:

CRAM Site Scores