Endangered Species Habitat Expanded in Marin

The "inverted T" area had 250 cubic yards of gravel removed and replaced with marsh soils. Sprinklers will ensure that plants don't get too dry during periods of neap tides this summer.

The “inverted T” area had 250 cubic yards of gravel removed and replaced with marsh soils. Sprinklers will ensure that plants don’t get too dry during periods of neap tides this summer.

The Creekside Marsh near Hal Brown Park is home to the endangered salt marsh harvest mouse, California Ridgway’s rail, and many other tidal marsh species.  The U.S. Army Corps of Engineers filled this marsh and many other tidal wetlands in the watershed with dredge spoils in the late 1960’s when the earthen channel for the Corte Madera Creek flood control project was constructed. In the mid-1970’s, Creekside Park, recently renamed Hal Brown Park, was developed and the marsh restored. This history of filling and excavation left behind bare areas that have not revegetated on their own for nearly five decades.  During the planning process, WRA discovered one of these bare soil areas was a remnant gravel road in the shape of a large “T”.  Other areas had soils that were too compacted for vegetation to grow or have been used as an un-authorized trail and wood deck.

The Transportation Authority of Marin (TAM) and Marin County Parks received permits to restore these bare areas of the marsh as compensation for a small area of impacts from the construction of the Central Marin Ferry Connection Multi-Use Pathway – a major improvement for non-motorized travel to and from the Larkspur Ferry Terminal over Sir Francis Drake Boulevard in Larkspur.

This site plan shows areas that were restored during Winter 2017.

This site plan shows areas that were restored during Winter 2017.

Construction to restore 1.42 acres of tidal marsh was recently completed prior to the beginning of Ridgway’s rail nesting season.  These areas previously did not support marsh vegetation because of the underlying gravel or soil compaction.  Construction replaced or amended and de-compacted the soils to better support tidal marsh plants like pickleweed, salt grass, and marsh gum plant.  Some topographic variability was also introduced to give salt marsh harvest mouse more areas of refuge during extreme high tides.  WRA’s principal ecologist Phil Greer and landscape architect Megan Stromberg led the permitting support, design, construction document preparation, and construction oversite over three years.  The project replaced more than 250 cubic yards of gravel with natural bay mud soil and installed nearly 11,000 native tidal marsh plants.

Congratulations to Marin County Parks and TAM for this great accomplishment and contribution to expanding endangered species habitat in Marin County.

Read more about the Central Marin Ferry Connection Multi-Use Pathway project here.