Chumash Freshwater Marsh
Weed Eradiction, and Creek Restoration
Project
– San Luis Obispo County
Service Provided: Environmental Constraints Analysis, Draft and Final EIR, Section 404, 1603, 401 Delineation and Permitting, Wetland Restoration Plan and Implementation, Water Quality Monitoring Plan, Construction Monitoring and Reporting, and Rare Plant Restoration Plan and Implementation.
Freshwater Marsh Habitat Restoration Planning, Implementation, Weed Removal, Five-Year Monitoring and Reporting: Envicom Corporation developed specifications for the restoration of 2.0 acres of seasonal freshwater marsh and 1.0 acres of willow wetland habitat. The project objectives included:
- Control and eradication of noxious weedy plant species;
- Provision of outdoor education and nature experiences for school children;
- Replacement of weedy plant species with ecologically beneficial wetland marsh;
- Establishment of seasonal ponds with dry periods in the late spring, summer, and early fall months;
- Improvement of wildlife habitat through enhancement of foraging and breeding habitat.
In association with the permitting agencies, it was determined that in-kind habitat replacement (freshwater marsh) would be most beneficial to wildlife given the rarity of this type of plant community in the region. To determine the most appropriate mix of plant species that would “mirror” the plant community to be lost, our biologists conducted quantitative and qualitative analysis of the existing freshwater seasonal marsh habitat in both the wet and dry seasons. We prepared a comprehensive plant species list, including both dominant and less common species that comprised the community. Prior to removal of the existing marsh habitat, our staff supervised and assisted with the collection of cutting, seeding, and plugs of spike-rush, umbrella sedge, dark-headed rush, bent grass, blue wild rye, giant ryegrass, and other species. The plants were grown and/or held at Native Sons Nursery and monitored by Envicom Corporation for health and vigor. We conducted a watershed search using aerial photographs and field reviews to locate an appropriate restoration site. Finding a site at the lower portion of Chumash Creek, belonging to the County Outdoor School Education Program, we presented the concept of developing walkways, viewing platforms, a diversity of habitats, and nature education programs themes around the restoration project to the School Board. The School Board approved of the concept and allowed the mitigation to take place on their property in a joint-use cooperative manner. However, the restoration site was covered 100% with Italian Thistle, Fuller’s Teasel, Bristly Ox-Tongue, and Prickly Sow-Thistle. This presented a major challenge. Working with a licensed contractor, eradication was accomplished over a one-year period by manual methods (cutting and bagging seed heads, removal of flowering stalks and roots) and with use of herbicides. We timed the removal efforts to avoid nesting season, as birds still used these dense thickets of weeds. Further, we experimented with several herbicides, as the effectiveness on one weed with one type would not ensure success with another type. For example, Garlon was required in the upland areas to remove the heartier teasel.
Upon clearing the site, Envicom Corporation coordinated with John Wallace and Associates, Engineers. The firm had developed the site grading plan, including establishing the floodway for determining the transition zones between wetland and upland plants and for implementing our concept for the ponds that would fill with rain water to create the marshes. Wallace and Associates monitored site grading and we approved the final grade. Our staff coordinated with the contractor to install the plants and instructed the contractor on the use of wire cages to protect the plants from herbivores. We were retained to conduct the required 5-year monitoring program, which we had developed. Quantitative assessment included measurements of relative cover of native plants and weed species and plant health and vigor using transects and quadrants. Qualitative observations included photographic documentation, general notes, comparisons, directions to crews for remediation, and wildlife observations. The project has successfully met all its restoration and mitigation objectives and is an integral part of the Outdoor School Education Program.