ARRA-Muddy Hollow Trail Improvements Project

Status Planning County Marin
Project Type Repair/Maintenance Location Not Mapped
Project Area (Acres) 0.69 Last Updated 13 April 2022
Project Abstract The ARRA-Muddy Hollow Trail Improvements Project is actually part of an effort to improve habitat conditions in the lower Muddy Hollow Creek watershed by rerouting 2,500 feet of the existing trail out of the floodplain/riparian area up the adjacent hillslope, which is mostly upland.
Administrative Region San Francisco Bay Regional Water Quality Control Board - Xavier Fernandez, SFBRWQCB

Project Identification

02-21-C0751 SWRCB - 401 Certification Letter (e.g., Site Number or WDID)
743050 SWRCB - CIWQS Place Number
2009-00297N USACE - DA File Number

Habitat Plan

Site NamePhaseActivitySubActivitiesHabitatSubHabitatAcresActivity StatusWater Regime
ARRA-Muddy Hollow Trail Improvements Project None Enhancement Unspecified Unknown/unspecified wetland habitat None 0.69 Construction planned

Related Habitat Impacts

Impact Project NameHabitatAcres LostType of Loss
ARRA-Muddy Hollow Trail Improvements Project-impact Unknown/unspecified wetland habitat < 0.1 Lost Permanent


ARRA-Muddy Hollow Trail Improvements Project Construction planned 0.69


DateTypeDescriptionSite Name
2010-09-10 Groundwork end Estimated date
2010-08-30 Project entered Project entered into database
2009-12-07 Project submitted Project submitted
2009-10-21 Groundwork start Estimated date
2009-10-15 Permit USACE permit issued
2009-08-18 Permit RWQCB permit issued
2009-08-18 Project start date Estimated date


Contact Lorraine Parsons USNPS U.S. National Park Service Not applicable/Unknown
Contact Amelia Ryan USNPS U.S. National Park Service Not applicable/Unknown
Contact Marla Lafer San Francisco Bay Regional Water Quality Control Board San Francisco Bay


No Data

Related CRAM Assessments

Visit DateVersionSite NameWetland TypeIndex Score
No Data

Performance Criteria

StatusDetailsEvaluation Date
Original criteria None Indicated 2009-12-07
Name File Type Submitted On Submitted By
Map of Planned Changes Photo 2010-09-02 Mariko Conner, SFEI
Wetland Tracker Form Other 2010-09-02 Mariko Conner, SFEI

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