General Description

Imperial Ponds Conservation Area is located on Imperial National Wildlife within a portion of the refuge known as the Intensive Management Area.  This management area is closed to the general public and consists of fields, marshes, and ponds that are managed for waterfowl, marsh birds, native fish, riparian obligate bird species, and other wildlife.

The conservation area has three primary features:  (1) ponds dedicated to native fish, (2) fields which were filled with dredged material from the pond excavation that will be planted with cottonwood-willow, and (3) field 18, which has been restored and is being managed as a marsh.

Fish Ponds

Six ponds were constructed to provide approximately 80 acres of habitat for endangered razorback sucker and bonytail fish species. The ponds are independently managed to provide a diversity of depths and habitat features, including rip-rap for cover, hummocks on which to place native wetlands plants, and an area where gravel was placed as spawning beds.  The Imperial Ponds are a major LCR MSCP focus area for restoration research as well as native fish life history research due to the size of the site and the built-in management tools (wells, pumps, independent water management, easy site access and onsite power). In addition, native plants are being established along selected pond shorelines to demonstrate suppression techniques for undesirable non-native vegetation, as well as bankline stabilization, maintaining wind-driven circulation in the ponds, and creating shade to lessen the impact of extreme summer heat in the ponds.

Cottonwood-Willow Forest

An existing 4-acre cottonwood-willow nursery on the refuge will be expanded by 34 acres on soils excavated from the ponds. The excavated material raised the fields 3 to 4 feet making them suitable for planting with cottonwood and willow. The additional forested area, interspersed with the ponds and others fields managed for waterfowl, is expected to create a vegetation mix that makes this an ideal site for attracting LCR MSCP covered species. Field leveling and irrigation system installation for the new area was completed in 2008. The fields are currently being managed with grass cover crops. Tree planting is scheduled for 2014 or 2015.

Field 18 Marsh Unit

A 12-acre marsh unit was created on the southeast corner of the intensive management area in 2008, and already has attracted California black rail, Yuma clapper rail, and western least bittern -- three LCR MSCP covered marsh bird species.

A fact sheet for this Conservation Area can be found here. Technical Reports for this Conservation Area can be found here.

Updated December 30, 2016

Imperial National Wildlife Refuge is located approximately 40 miles northeast of Yuma, California and includes lands managed by the U.S. Fish and Wildlife Service in both the states of California and Arizona.  Imperial Ponds Conservation Area is located in Yuma County, Arizona, and is bounded by the Colorado River to the west at River Mile 59 and the Refuge headquarters to the east.

The Conservation Area is located on a portion of Imperial National Wildlife Refuge that remains closed to the general public to minimize disruption to wildlife.  Information on Imperial National Wildlife Refuge, including location, purpose, and regulations, can be found on their website at this link.

For specific information on the Conservation Area, please contact Terry Murphy, Restoration Group Manager, at tmurphy@usbr.gov.

The image below shows a close up of the conservation area.

Each Conservation Area targets certain LCR MSCP covered and evaluation species habitats. Below, on the left, is a list of the LCR MSCP species in which habitat will be targeted for creation for in this particular conservation area. To the right is a list of LCR MSCP species that, through monitoring, have been found utilizing the conservation area.

Fisheries

Water quality monitoring is conducted throughout the ponds both daily and monthly.  Daily monitoring occurs at three locations throughout each pond using Troll 9500s.  Daily parameters measured include temperature, conductivity, turbidity, dissolved oxygen (DO), and pH.  Monthly data is collected using a multi-parameter water quality instrument.  Vertical profiles will be taken at three pre-determined points throughout each pond.  Monthly parameters to be measured include temperature, conductivity, total dissolved solids, DO, and pH.  Monthly sampling will also be conducted at three preset water quality stations within each pond.  Samples will be sent to the Reclamation laboratory for processing.  Sample analysis includes physical properties (conductivity, pH, total disolved solids (TDS), total suspended solids (TSS)), major and minor ions, metals, selenium, and nutrients (nitrate, nitrite, total nitrogen, ortho-phosphate, and total phosphate). 

Fishery management and research within the ponds consist of conducting monthly population estimates for razorback sucker and bonytail with 134.2 kHz passive integrated transponder (PIT) tag for individual identification, evaluating survivorship, health, growth, and recruitment, evaluating the use of available habitat types, and assessing biomass on non-native species.

Bird Monitoring

Surveys for covered birds are conducted annually. Marsh bird surveys are conducted in March, April, and May at established points for California black rail, western least bittern, and Yuma clapper rail.

Mammal Monitoring

Small mammal live trapping is conducted annually to monitor presence of Yuma hispid cotton rats and desert pocket mice at the conservation area.

Riparian Management

Acreage Map

This map shows the acreage for this area. You can click on the map for a larger view.

This gallery includes photos of this conservation area. If you require larger photos, please contact our webmaster Michelle Reilly at mreilly@usbr.gov.