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 IID’s operation and maintenance activities related to the conveyance of irrigation water and for potential avian reproduction impacts due to increased selenium concentrations through water volume reduction in drains caused by the water transfer conservation measures. 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 various 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. Project goals include creating habitat, minimizing irrigation water usage, evaluating design, construction and management techniques, and minimizing construction impacts. The Yuma Ridgeway’s rail and California black rail are target indicator species for the success of the marsh.
Phase I of the Managed Marsh is approximately 365 acres of emergent wetland, riparian and scrub-shrub habitat. 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.
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.
Phase II of the Managed Marsh is approximately 350 acres of emergent wetland and riparian habitat. 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.
The riparian woodland habitat is designed to provide willow trees a more stable growing area on raised islands with emergent wetland and open water in adjacent areas Emergent wetland cells will be flooded with 2-4 feet varied water depths of saturated soils. Emergent plants include: cattails, bulrush, rush, scattered woody vegetation and saltgrass are along the cell perimeters. Both riparian and emergent wetland cells feature a moat of deeper, open water on the north, west and south edges of cells. Native honey and screwbean mesquites are planted in the native tree buffer zones.
Phase III of the Managed Marsh will be located north of Phase I, between Pound and Hazard Roads, bounded by English Road on the west and Highway 111 on the east. This phase will be predominately riparian habitat with willow trees. Construction is expected to begin and be completed in 2019.
Cost of design, construction and operation (including irrigation water) 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:
- Park in designated parking locations
- Do not block access roads
- No overnight camping
- No fires or smoking
- Pick up all trash and empty hunting shells
- No permanent blinds
- Speed Limit: 10 mph
The marsh may be temporarily closed to the public due to maintenance or monitoring activities at any time.