Rural Nevada Water Tour, May 21-23, 2004
A Brief Overview of the White River Ecosystem
Once a tributary to the Colorado River, the White River is now a disrupted series of intermittent creeks, seeps and springs throughout it entire course, from its northern beginning in the White Pine Range west of Preston, to its southern terminus near present day Moapa. Where surface waters flow freely, the White River ecosystem supports freshwater wetland plant communities consisting largely of emergent wetland vegetation associated with standing water pools. Dominant plant species include bulrush (Scirpus spp.), cattail (Typha spp.), sedge (Carex spp.), spikerush (Eleocharis spp.), and various species of grasses (Poaceae). Surrounding these emergent marsh areas are alkaline meadows characterized by the presence of tolerant species such as saltgrass (Distichlis spicata) and alkali sacaton (Sporobolus airoides). The outlying areas also include alkaline substrate habitats hosting suites of endemic plants and butterflies.
The aquatic environments of the White River Valley contain a rich assemblage of isolated endemic fishes and springsnails. The White River fish fauna in particular is highly distinctive. Along the entire length of the pluvial White River and its interrupted waters, six different genera of fishes – springfish (Crenichthys), spinedace (Lepidomeda), chub (Gila), speckled dace (Rhinichthys), desert sucker (Catostomus), and sculpin (Cottus) – remain extant today with various species and subspecies isolated from one another. The Genus Crenichthys, along with Empetrichthys (poolfish native to Pahrump Valley) are surviving representatives of the family Empetrichthyidae, an unusual taxonomic group of fishes found only in Nevada. This genus of fish is represented in the White River ecosystem by two full species: the White River springfish (C. baileyi, of which there are 5 different subspecies), and the Railroad Valley springfish (C. nevadae). Perhaps with the exception of the sculpin, all of these native fishes are endemic to the White River system.
The following narrative summarizes the diversity and richness of biological resources found within the White River ecosystem, moving from south to north. Day 1 of the tour will take us into, or by, many of these areas. On Day 2, we will visit Spring and Lake valleys, located north and east of the White River Valley proper. The biological resources of these valleys, while representative of the basic character of the Great Basin, also offer several opportunities to visit unique ecological communities and species of plants and animals found in very few other places in the world.
Pahranagat Creek, at the lower end of the pluvial White River system is 25 miles in length, and originates from two warm water springs, Ash and Crystal. The Creek and its spring sources provide habitat for three endangered fishes found nowhere else in the world. The Pahranagat roundtail chub (Gila robusta jordani), the most critically endangered species in the State of Nevada, is restricted to the river mainstem. At last count, the Pahranagat roundtail chub population was down to only 14 individuals. The spring pools and outflows of Ash, Crystal, and Hiko springs are the only native habitats of two listed subspecies of the White River springfish (Crenichthys baileyi baileyi and C. b. grandis).
Pahranagat Creek ultimately discharges into a series of reservoirs on the Pahranagat National Wildlife Refuge, a regionally significant waterfowl and riparian breeding bird habitat. The Refuge supports healthy populations of the endangered Southwestern Willow Flycatcher, Yellow-billed Cuckoo (a candidate for Endangered Species Act listing), and many other species of riparian breeding birds. The Pahranagat Valley also supports a population of the Pahranagat Valley montane vole. Interestingly, most voles are found on mountain tops. The Pahranagat Valley montane vole, and the related Ash Meadows vole (if extant) in Nye County, Nevada, are adapted to low elevation wet valleys and are clearly Pleistocene faunal remnants. Near the town of Alamo, the desert tortoise (Gopherus agassizii) has its most northerly known occurrence in Nevada. Another rare reptile, the banded Gila monster (Heloderma suspectum cinctum) attains its northernmost Nevada occurrence just south of the Sunnyside area of the White River Valley.
A Rare Plant Assemblage – The Sunnyside area harbors several globally rare plant species that are restricted to eastern Nevada and endemic to the Great Basin Ecoregion, as defined by The Nature Conservancy. The Sunnyside green gentian (Frasera gypsicola), White River catseye, (Cryptantha welshii), southwestern peppergrass (Lepidium nanum), Tiehm blazingstar (Mentzelia tiehmii), Parish phacelia (Phacelia parishii), Charleston grounddaisy (Townsendia jonesii), one-leaf Torrey milkvetch (Astragalus calycosus var. monophyllidius), and starveling milkvetch (A. jejunus var. jejunus) all have viable occurrences here. The predominant plant community in which most of these plant populations occur is itself unusual. Pygmy sagebrush (Artemisia pygmaea) dwarf shrublands are restricted to the Great Basin and adjacent ecoregions. This plant community, typically occurring in small patches, is usually tied to peculiar edaphic situations forming badlands, with sparse vegetation and supporting a variety of rare plant species.
Kirch Wildlife Management Area, located in the Sunnyside area of the White River Valley, encompasses the Flag Springs complex. In 1995 and 1996, the last remaining population of the endangered White River spinedace (Lepidomeda albivalis), located at North Flag, had dwindled to less than 20 individuals. More recently, the collaborative efforts of State and Federal resource management agency personnel successfully increased fish numbers and addressed habitat improvement needs. Today, there are more than 3,000 spinedace in Flag Springs. This is a great example of an endangered species management success story.
The towns of Lund and Preston have a diversity of springs that contain a number of endemic fishes, including White River spinedace (Lepidomeda albivallis), White River speckled dace (Rhinchthys osculus spp.), White River desert sucker (Catostomus clarki intermedius), Preston White River springfish (C. b. albivalis), and Moormon White River springfish (C. b. thermophilus). Since the early 1900s, many of the springs have been developed for irrigation, recreational, and domestic water needs. Consequently many of these springs have lost much of their fish fauna through introductions of exotic species, impounding or diverting of surface waters, and habitat loss.
A Continuing Success Story – The Endangered White River spinedace was one such species that had previously been lost in this area. Endemic to the upper White River system, the spinedace was extirpated from the Preston and Lund town spring systems. During the past few years, a multi-agency and local landowner effort restored habitat at Indian springs in Preston. This action allowed the reintroduction of the White River spinedace as well as the White River desert sucker to Indian Springs in March and April of this year. Prior to this reintroduction, only a single population of the White River spinedace existed in the wild, at Flag Springs near Sunnyside. Now for the first time since the 1980s a second population of White River spinedace exists in its native habitat.
Duckwater (Railroad Valley) area
There are two species of fishes native to this area, the Duckwater Creek tui chub and the Railroad Valley springfish. The tui chub inhabits many of the cold water springs, seeps, and creeks in this system. The Railroad Valley springfish is a thermal obligate that resides in the many thermal springs and pools of Railroad Valley and in warm springs on the Duckwater Reservation. The relict fish fauna in this area is exceptional in that the tui chub is of Lahontan Basin origin while the springfish is of Colorado River basin origin, indicating that there was a Pleistocene connection between each of the basins. This is the only known valley in Nevada in which fishes from each of these historic drainage basins co-occur.
Spring Valley and Lake Valley area
Spring Valley, Lake Valley and adjacent areas provide classic examples of Basins and Desert Scrub and Sagebrush Semidesert ecological system groups, as defined by The Nature Conservancy through its Great Basin Ecoregion planning efforts. The basins and desert scrub systems characterize the lowermost elevations of the ecoregion, occupying alluvial flats and playas on the basin floors, and alluvial fans and mountain-valley fans on the surrounding piedmont slopes, and covering about 37 percent of the Great Basin ecoregion. Big greasewood and shadscale shrublands are typical plant communities here.
The sagebrush semidesert is, simply put, the “Sagebrush Ocean” that covers about 33 percent of the ecoregion. The lowest elevation communities of the sagebrush semidesert occur on dry, non-saline valley floors, toeslopes and lower slopes. Sagebrush steppe, comprised of dense sagebrush shrublands with a significant grass understory occur at moderate elevation above 5,200 feet on flat or gentle bajada slopes. Sagebrush ecosystems provide habitat for the Greater Sage Grouse (Centrocercus urophasianus) and other sagebrush associated species such as the pygmy rabbit (Brachylagus idahoensis). Sage grouse may be found in valley bottoms associated with alfalfa, wet meadows, and riparian areas, but are commonly observed in higher elevation shrub communities.
The pygmy rabbit is the smallest rabbit in North America. Although it can be confused with cottontail rabbits, pygmy rabbits have shorter ears and have a uniformly brown tail. Pygmy rabbits are highly associated with dense, tall stands of sagebrush. This rabbit is the only known North American rabbit to dig their own burrows, requiring deep, loose soil that is associated with taller stands of sagebrush. Their secretive nature and nocturnal activity make these small rabbits easy to overlook.
There are various unique ecological communities and rare species present in this general vicinity. A few of these are highlighted below:
Baking Powder Flat: Located in Spring Valley, Baking Powder Flat is one of four currently known locations for the Baking Powder Flat blue (Euphilotes bernardino minuta), a rare butterfly endemic to the Central Mountains section of the Great Basin ecoregion, as defined by The Nature Conservancy in its Great Basin Ecoregion plan. Its host plant, Shockley buckwheat (Eriogonum shockleyi var. shockleyi), is a common, mound-forming plant often found on fine-textured substrates, but it reaches exceptional diameters at this location and is the predominant plant in the valley bottomland. Baking Powder Flat is the largest contiguous habitat for the Baking Powder Flat blue.
Spring Valley Swamp Cedars: Central Spring Valley contains the largest of three known occurrences of a valley bottom ecotype of Rocky Mountain juniper woodlands. This rare plant community is endemic to Central Mountains section of the Great Basin ecoregion. All three known locations occur within the BLM’s Ely District. As the largest stand, the Spring Valley Swamp Cedars is an exemplary occurrence of this rare plant community.
Shoshone Ponds: Located within another exemplary stand of “swamp cedars”, Shoshone Ponds is specially designated by BLM as a rare desert fishes refugium and has, at various times, supported up to five rare fishes – Pahrump poolfish, bonytail chub, Moapa dace, Big Springs spinedace, and relict dace. Currently, only the endangered Pahrump poolfish (Empetrichthys latos) and relict dace (Relictus solitarius) occur in the ponds. The surrounding swamp cedars provide habitat for a rare butterfly, the dark sandhill skipper (Polites sabuleti nigrescens), that is endemic to the Central Mountains section of the Great Basin ecoregion.
Other Species of Concern in Eastern Nevada
Bats – Of the 23 species of bats occurring in Nevada, 13 species occur within the tour area, including one species, the spotted bat (Euderma maculatum), that is listed by the State of Nevada as an Endangered species. Bats occupy specialized niches in the landscape, as they are the only nocturnal predators of night flying insects, typically eating more that 50 percent of their body weight in insects each night. For their size, bats live relatively long lives and reproduce slowly, with most species only having one young per year. Most species of bats are highly sensitive to disturbance, particularly during the maternity and hibernating seasons. Despite what is commonly thought to be true, bats are not vicious, rabid animals, but are beneficial mammals that are key to healthy, fully functioning ecosystems.
Amphibians -- The northern leopard frog (Rana pipiens) was once regarded as the most abundant amphibian species in Nevada. While the species has declined in geographic distribution and numbers, viable populations remain in Spring Valley. A few individuals also have been found in Pahranagat Valley. While research is currently underway on the taxonomy of the Western toad (Bufo boreas) assemblage, scientists may have found a full new species that is endemic to Railroad Valley Wildlife Management Area in Nye County. The only Nevada populations of southwestern toad (B. microscaphus) occur in the upper reaches of Meadow Valley Wash in Lincoln County. The Great Plains toad (B. cognatus) is found rarely in Nevada, and it also exists in upper Meadow Valley Wash.
For more information on the flora, fauna, and ecological systems of Nevada contact:
Nevada Natural Heritage Program
Department of Conservation and Natural Resources
1550 East College Parkway, Suite 137
Carson City, Nevada 89706-7921
Voice: (775) 687-4245 fax: (775) 687-1288 web: www.heritage.nv.gov/
The Nature Conservancy of Nevada
One East First Street, Suite 1007
Reno, Nevada 89501
Voice: (775) 322-4990 fax (775) 322-5132 web: www.nature.org