• Red Rocks with water in front of them in the desert.
  • Clouds behind Joshua Tree and bushes.
  • Desert flowers blooming in bushes in front of mountains in the desert.
  • Setting sun reflecting of clouds of orange and blue behind a joshua tree.
  • Hoover Dam intake towers with water behind the dam showing that it is not full.


Defining ecosystem water needs and assessing impacts of climate change and water diversion on riparian and aquatic species and ecosystems of the upper Gila River in New Mexico

Science Need(s)

Projecting the resiliency and vulnerability of natural resources that are affected by water resources management in a changing climate; Interactions between ecosystems and hydrology, Climate change impact to surface water and ground water dependent habitats and species; Climate change impact to the interaction between surface water and ground water resources; Climate change impact to future water supply and resource availability for humans and ecosystems

Grantee: The Nature Conservancy in New Mexico
Principle Investigator: David Gori
Cooperative Agreement:  $132,871 in non-Federal funds and $129,887 in Federal funds provided by BOR
Project Duration: 2012-2014

Project Goal(s)

The goal of this project is to define the ecosystem water needs of the upper Gila River in New Mexico and to assess the probable ecosystem impact of the proposed diversion, considering current and projected future climate. We will identify potential impacts of change on hydrological processes, riparian vegetation, and aquatic habitat and associated wildlife species. To achieve this goal, we will synthesize existing scientific literature specific to the Gila River and southwestern rivers on hydrology; fluvial geomorphology and flood history; stream flow regimes and riparian vegetation ecology; and wildlife and flow relationships (Task A). New analyses of hydrologic, geomorphic, riparian vegetation and fish data will be used to evaluate the probable ecosystem impact of diversions under changing climate conditions (Task B). Partners will develop three flow scenarios: 1) climate change projections for streamflow for the Gila River, including timing and volume of peak flows and base flows; 2) a diversion scenario that compares diversion altered hydro graph (daily flows) to the historical hydrograph to quantify changes in magnitude, frequency, timing, and duration of flows; and 3) the combined effects of climate change and diversion on the flow regime (Task C). Upon completion of a background report that incorporates the literature synthesis, data analysis, and modeling, we will convene a flow-ecology workshop that gathers additional information about river function to develop flow-ecology response relationships for selected riparian and aquatic species (Task D). Workshop results will be summarized in a final report (Task E).

Brief Project Description

The substantially natural hydro graph of the upper Gila River supports one of the highest levels of aquatic and riparian biodiversity in the region, including the largest complement of native fishes and some of the best remaining riparian habitat in the lower Colorado River Basin. Native vegetation dominates the broad and structurally diverse floodplain, creating habitat for hundreds of birds and other wildlife. Two of the Gila's fish species, spikedace and loach minnow, and a neotropical migratory bird, the southwestern willow flycatcher, are federally listed as endangered. The yellow-billed cuckoo, a candidate species for listing, nests in the Cliff-Gila Valley. Changes to the river's hydrology, including peak flows, base flows and groundwater levels, may significantly degrade the aquatic and riparian ecosystem. The Arizona Water Settlements Act (AWSA) authorizes the expenditure of up to $128 million in federal funds to build a New Mexico Unit that could divert up to 14,000 acre-feet annually.

Project Location

Upper Gila River in New Mexico

Project Tasks

  • Review and compilation of published and unpublished literature and data on hydrology, geomorphology, flood history, riparian vegetation, and wildlife
  • Complete data analyses for the Gila River on river function: groundwater & surface water interactions, riparian vegetation, and wildlife
  • Complete climate change modeling; develop flow projections/scenarios for Gila River
  • Develop flow scenarios for New Mexico and climate change
  • Convene experts' workshop to further develop response relationships and flow recommendations
  • Complete final report
  • Develop outreach materials for distribution to local, state and regional stakeholders; implement communications plan

Project Deliverables

  • Report including information/literature synthesis chapters, summary of workshop outcomes, environmental flow recommendations, flow-ecology response functions and anticipated impacts of AWSA diversions and climate change on riparian/aquatic species.
  • Outreach materials.
  • Peer-reviewed journal articles.

Documents Available for Download