A section of the Managed Marsh Complex will be temporarily closed over the next few weeks so an assessment can be conducted to gauge the success of the habitat. While Phase I will remain open, the section consisting of Phase II, which is located between the south side of McDonald Road and Schrimpf Road, will be closed intermittently between November 8 and 21; however, the section will remain open during the weekends.
- Closed Thursday and Friday, 9-10
- Open for the weekend, 11-12
- Closed Monday through Friday, Nov 13-17
- Open for the weekend, 18-19
- Closed for Monday and Tuesday, 20-21
- Open for Thanksgiving holiday
The Managed Marsh Complex is located adjacent to Highway 111, about two miles south of Niland, CA and is part of the mitigation required under the Quantification Settlement Agreement Water Transfer. It provides mitigation for both the reduction in water volume in the drains, caused by the transfer and provides mitigation for IID’s operation and maintenance activities related to the conveyance of irrigation water. The size of the marsh complex was determined based on a vegetation assessment, conducted in 2005 that quantified and classified the vegetation communities within the IID drain infrastructure.
The marsh is a three phase complex to total approximately 959 acres of habitat for IID’s HCP Drain Covered Species. Drain species include: raptors, wading and shore birds, waterfowl and passerines. Phase I was completed in 2009, Phases II was completed in 2014 and Phase III will be completed in 2019.Phase I of the Managed Marsh is approximately 365 acres of emergent wetland, riparian and scrub-shrub habitat. Information gathered from this phase was used to improve the design for Phase II. Both Phases I and II will be used to improve the design for Phase III. Project goals include creating habitat, minimizing irrigation water usage, evaluating design, construction and management techniques, and minimizing construction impacts. The ridgeway rail and California black rail are target indicator species for the success of both phases.
Construction began in March 2009 with watering of the site prior to earth moving to minimize dust emissions. Construction was completed in August 2009 with vegetation planting and seeding in September and October. Approximately 60 thousand plants were transplanted by the Southwest Conservation Corps, California Conservation Corps and local farmers led by AMEC Earth & Environmental. Additionally channels were cut into two of the P3 cells and planted with willows and cottonwood in June of 2010. Mesquite trees were also planted in the Buffer Zones at this time.Managed Marsh Birds
Two cell designs were constructed for Phase I: 15 acre rectangular cells and varying size cells built on topographic contours. Rectangular cells include an L-shaped dispersion channel in the northeast corner. Varying size cells have a 2 to 3 foot deep moat around the perimeter to allow for varying water depths. The cells are designed for flow through, and methods for circulating water include: direct flow through each cell to the discharge drain and cascading water from one cell to the next. Buffer Zones on the east and west edge of the marsh provide a buffered area from roads and agriculture fields. Buffer Zones are designated as native tree habitat mitigation and provide habitat for small mammals.
Construction began in September 2014 and was completed by Granite Construction and IID. Approximately 17 thousand trees were planted in December 2014 by American Conservation Experience led by AMEC Earth & Environmental. The design of Phase II was similar to Phase I, but includes larger cells on the topographic contour and wider berm roads. Three of the cells were designed with islands where trees were planted, and the water level can be managed more efficiently. All other cells were seeded with a mix of emergent vegetation or left to have natural vegetation volunteer into the site. Half of each Buffer Zone was planted with native tree habitat.
Vegetation habitats within the cells include: riparian woodland, emergent wetlands and scrub-shrub. The riparian woodland habitat is designed to mimic desert riparian corridor habitat with meandering channels. Areas adjacent to channels are lined with willows and cottonwoods and upland areas will be mostly dry. Emergent wetlands will be flooded with 2-4 feet varied water depths of saturated soils. Emergent plants include: cattails, bulrush, rush, scattered woody vegetation and saltgrass in dryer areas. Scrub-shrub habitat mimics mesic bosque and willow/cottonwood flood plains and is periodically flooded to mimic the floodplain area of a river. Scrub-shrub vegetation includes: willows, cottonwoods and mesquites. Native tree habitats in the buffer zones include mesquites.
Cost of design, construction and operation is funded through the QSA Joint Powers Authority. Members include: Imperial Irrigation District, San Diego County Water Authority, Coachella Valley Water District and California Department of Fish and Wildlife.
The Managed Marsh is open to the public. Please following the Managed Marsh Rules:
- Do not block access roads
- Do not drive on roads when wet
- No overnight camping
- No fires
- Remember to clean up after yourself
- No motorized boats
- Wading is permitted
- The marsh may be temporarily closed to the public due to maintenance or monitoring activities at any time.