Virgin River Research

The Virgin River is a dynamic hydrologic system that supports several unique and fragile ecosystems. There are two endangered species of fish, at least two endangered species of bird, and many sensitive species of both plants and animals inhabiting the Virgin River corridor. The introduction of non-native fish and plants, and a decrease in habitat quality have had detrimental impacts on the biological resources of the Virgin River.

Because it is important to the environment

The Water Authority is taking a proactive approach to resource management by funding and administering seven biological research projects in the lower Virgin River:

• Water consumption of native and non-native vegetation
  

• Riparian study from Littlefield, Nev., to the northern boundary of the Lake Mead National Recreation Area
  

• Studies of th Southwestern willow flycatcher as well as vegetation and plant studies
  

• Studies of the Virgin River chub and woundfin
  

• Small mammal studies
  

• Bat monitoring
  
  
• Vegetation and plant studies

These research projects help quantify water resources and set the stage for future environmental compliance. Information gathered and technologies developed by these projects could prove to be quite useful to resource management efforts in other areas where the same species exist such as the Colorado River.

That pesky, invasive tamarisk

One of the research projects funded by SNWA was conducted by the University of Nevada, Las Vegas to determine water consumption of native and non-native vegetation in the river corridor. Much of the riparian vegetation in the Southwest, including the Virgin River, has been replaced by a highly invasive, non-native tree called saltcedar (Tamarix ramosissima).

Riparian corridor study

The first research project is a study of the riparian corridor from Littlefield to the northern boundary of the Lake Mead National Recreation Area. This riparian study is being conducted to assess the structure of plant and animal communities in the corridor, and how these communities change seasonally and with fluctuations in environmental conditions.

Where the birds are

In addition, the Water Authority signed a Memorandum of Agreement with the Bureau of Reclamation to fund surveys for the federally-endangered southwestern willow flycatcher (Empidonax traillii extimus), yellow-billed cuckoo (Coccyzus americanus), the federally-endangered Yuma clapper rail (Rallus longirostris yumanensis) and other sensitive bird species along the lower Virgin and Muddy Rivers and Lake Mead.

A geographic information system (GIS) database is being used to manage information gathered by the study. The use of GIS will be instrumental in analyzing the relationship between community structure and the environment.

Virgin River chub and woundfin

The second research project is a population study of the two endangered species of fish: Virgin River chub (Gila seminuda) and woundfin (Plagopterus argentissimus).

This study involves sampling populations of these fish in three four-mile sections of river. Information gained from this research will help the Water Authority assess the seasonal distribution of these fish and the habitat requirements needed to preserve viable populations.

By understanding the relationship between the biological community and the physical environment of the river, SNWA will be able to better manage and help other local, state and federal agencies manage the environmental resources of the Virgin River.

Habitat mapping and sensitive plant surveys

SNWA is currently conducting habitat mapping and sensitive plant surveys along the Virgin River in order to better understand the habitats and plant species within and around the river. This study involves examining aerial photography and conducting subsequent field checks to verify the habitat types. Field surveys are also conducted to document plant species within the habitats, including any sensitive plant species.

Small mammal surveys

SNWA is conducting regular small mammal surveys along the Virgin River in order to document the small mammal species that use Virgin River habitat. The survey effort includes using mammal traps to capture the small mammals unharmed, document their species and condition, and then return them to the wild. Species documented to date include Merriam's kangaroo rat (Dipodomys merriami) and pocket mouse (Perognathus). This survey effort will help SNWA determine the diversity and range of small mammals along the Virgin River.

Bat monitoring

SNWA is conducting bat surveys and monitoring using a recording system called the AnaBat bat detector, which can record the signals of bats for computer analysis and species identification. This effort will help SNWA determine the diversity of bat species along the Virgin River and the habitat that the Virgin River provides for the species.

Virgin River Fishes Recovery Team

The Virgin River Fishes Recovery Team was formed in 1990 after the listing of Virgin River chub as an endangered species in 1989. SNWA is an active participant on this recovery team, which is responsible for initiating studies and project to aid in the recovery of Virgin River fish species.

Lower Virgin River Recovery Implementation Team

The Lower Virgin River Recovery Implementation Team has drafted a strategy to serve as an to assist in the recovery of a variety of species and habitats along the Virgin River. SNWA is an active participant on this recovery implementation team, which is chaired by the U.S. Fish and Wildlife Service.