Author: Kurt Johnson, National Climate Change Scientist, U.S. Fish and Wildlife Service
Raccoon in Hagerman National Wildlife Refuge. U.S. Fish and Wildlife Service.
Water is the lifeblood of western wildlife. Almost always in short supply, wildlife usually exists where surface water is available—springs, seeps, vernal pools, streams, wetlands. Water shortages are a part of the natural cycle, and western wildlife species are often well adapted to dry conditions, whether through physiological mechanisms or behavior. Even extended droughts are a part of the natural cycle.
The West is certainly no stranger to drought. While the 1930s Dust Bowl could be described as the “poster child” for drought in this country, devastating droughts have occurred before and since, notably in the 1950s and late 1980s. The recent droughts in Texas and the Great Plains and the ongoing drought in California highlight an increasing trend of more frequent and more intense droughts in the West. This is due in part to ongoing climate change and increasing climate variability. All signs are that this trend will continue in coming decades in response to increasing air temperatures and changing precipitation patterns. One recent paper modeled potential future drought conditions in the Southwest and Central Plains of western North America and obtained results that pointed to “a remarkably drier future that falls far outside the contemporary experience of natural and human systems in Western North America, conditions that may present a substantial challenge to adaptation” (Cook et al. 2015).
U.S. Fish and Wildlife Service biologists and managers are rightly concerned about the impact that these extended droughts are having—or will have in the future—on fish, wildlife, plants and habitats for which the agency is responsible. To assess recent drought impacts on resources under their jurisdiction, this past summer (2015), all eight service regions prepared an initial qualitative assessment of impacts to national wildlife refuges, threatened and endangered species, migratory birds, certain migratory fish species, and national fish hatcheries (collectively termed trust resources). Each region’s assessment included a description and evaluation of recent impacts of drought on trust resources and the Service’s management responses to those impacts.
Sandhill cranes in flight at the Bosque del Apache National Wildlife Refuge.
U.S. Fish and Wildlife Service.
Drought Impacts on Western National Wildlife Refuges
For this blog I have focused on one trust resource—national wildlife refuges (refuge or NWR)—as an example of drought impacts and service responses. Although drought conditions have not been confined to the West, refuges in the West have been particularly hard hit.
Central Valley refuges in California are reeling from water shortages. Since the passage of the Central Valley Project Improvement Act in 1992, some water allocations were cut back and other allocations not available at all for the first time in 2014 and 2015. Water allocations have been, on average, only half of full water deliveries. This is limiting the refuges’ ability to divert water for habitat use, resulting in fewer flooded wetland acres, earlier loss of wetlands that do get flooded, and reduced wetland food production (by over 80% in some refuges).
In southern Oregon, water deliveries to Lower Klamath NWR from the Klamath Project have significantly declined in recent years (even before the drought) and nearly ceased in the past two drought years.
In eastern Idaho, Camas Creek, the main surface water supply for Camas NWR, only flowed for two days this year. It was the lowest recorded flow since measurements began 90 years ago. The low flow is the cumulative impact of this year’s low snowpack as well as increases in surface water withdrawals and upstream groundwater pumping that have occurred over the past few decades.
Refuges in the Southwest are also suffering mightily. In New Mexico, the drought of 2000-2013 significantly impacted the spring system at Bitter Lake NWR, which is habitat for a suite of endangered and unique species, and also impacted Bosque del Apache NWR’s ability to manage water for both endangered species and managed wetland needs, resulting in recurrent water management challenges. From 2010 until May 2015, significant and persistent drought impacted Hagerman NWR in northern Texas, resulting in mortality of trees and mid-story vegetation along creeks, streams and ponds.
In the Great Plains, refuges in Kansas have been particularly hard hit by drought. Wetlands on Quivira NWR have frequently been dry in the fall in recent years, reducing habitat for migrating waterfowl and whooping cranes.
Bitter Lake National Wildlife Refuge. U.S. Fish and Wildlife Service.
Responding to the Challenge
To address the near-term impacts of drought on western refuges, managers have undertaken a wide range of actions related to water management, including:
- Prioritizing habitat areas receiving water in managed wetlands
- Receiving water allocations later in the season to ensure water for migrating birds
- Increasing groundwater pumping to supplement surface water for managed wetlands
- Allowing lower-priority wetlands to dry
- Reducing grazing on wetlands
- Taking advantage of low water levels to treat invasive plants
- Working with water management agencies on water rights/allocations
- Identifying gaps and needs in water management infrastructure
- Monitoring water flows at refuges
To prepare for the long term, service biologists and managers are working with other agencies and academic researchers to address drought impacts and water management needs on a landscape scale, employing new and creative planning and management approaches. In California’s Central Valley, Dan Frisk, Project Leader at the 68,000-acre Sacramento NWR Complex, is looking for tools to prepare the refuge for the future by expanding the refuge’s traditional partners to include the California Landscape Conservation Cooperative (LCC) and its Central Valley Landscape Conservation Design (CVLCD) Project. The CVLCD project engages managers and scientists who have been working for decades on conservation in the Central Valley, including state, federal and local agencies, non-profits and existing partnerships.
The CVLCD process began with a scenario exercise that produced a set of four plausible but very different futures for the region. The resulting “Central Valley Future Scenarios” provide a basis for selecting useful management options in spite of uncertainty over which future will play out over the next 50 years. The partnership next identified a list of priority natural resources—a list of habitats, groups of species and individual species whose health would scale up to a functioning network of ecosystems for the Central Valley. Experts then came together to assess the vulnerability of the priority habitats and species to changes described in the future scenarios. The next step for the partnership is to develop adaptation strategies and a set of maps to guide climate-smart actions in the future.
By working creatively with partners through LCCs, Service biologists and managers are increasingly developing and implementing landscape conservation designs that will enhance the resilience of trust resources to drought and other stressors for the foreseeable future.
Dr. Johnson presented on drought and natural resources management at RNRF’s Congress on Sustaining Western Water in December 2015. Visit the congress website for more information, including speaker presentations and videos.
Cook, B.I., Ault, T.R., & Smerdon, J.E. (2015). Unprecedented 21st century drought risk in the American Southwest and Central Plains. Science Advances, 1(1). http://advances.sciencemag.org/content/1/1/e1400082