The Decline of Ash Meadows, a Unique Desert Ecosystem^[1]

Cynthia D. Williams^[2]

Abstract.—Ash Meadows is a unique hydric ecosystem of the Amargosa Desert located in southwestern Nye County, Nevada, and southeastern Inyo County, California. The approximately 162-km² area is dominated by over 30 springs and seeps that support a wide variety of plant and animal life, including nearly 30 endemics. Ash Meadows was apparently heavily used by several Indian cultures and later mined for peat and clay around 1910 to 1930. Since the late 1960s, the area has been subjected to a variety of agricultural, industrial, residential, and mineral development schemes, the most recent of which threatens to cause the demise of the ecosystem.

Introduction

Ash Meadow is a unique and biologically rich ecosystem, consisting of approximately 16,200 ha. in southwestern Nevada and southeastern California. It is located in the Amargosa Desert about 64 km. east of Death Valley and 145 km. northwest of Las Vegas (fig. 1). More than 30 springs and seeps discharge a total of 17,000–20,000 acrefeet of water annually in the Ash Meadows area, creating an oasis in the otherwise arid Amargosa Desert. Many of the springs are large, with headwater pools 6–10 m. in diameter (fig. 2). Water temperatures range from 26°C. to 38°C. The large spring discharge creates significant marsh areas for waterfowl and other migrating birds. At least 20 of the springs contain native fish, and most, if not all, contain endemic species of molluscs or insects. Additionally, several rare plants depend on the moist areas surrounding the springs for their survival.

As with much of the Great Basin, the Ash Meadows area was considerably wetter during the late Pleistocene, supporting Lake Ash Meadows as an ephemeral feature (Snyder etal . 1964). Because of elevational differences, the springs of Ash Meadows were isolated in three stages by the post-pluvial desiccation of Lake Ash Meadows. Devil's Hole, at approximately 732 m., was the first aquatic habitat to become isolated as the waters of Lake Ash Meadows receded. The period of isolation has been estimated at upwards of 30,000 years.^[3] The mid-level springs, including Scruggs, Indian, Marsh, School, and Mexican springs, became isolated 4,000–10,000 years before present (YBP). Isolation of the lower elevation springs, including Big, Point-of-Rocks, Jack Rabbit, Forest, Bradford 1, Bradford 2, Bradford 3, Crystal, Longstreet, Rogers, and Fairbanks springs, occurred more recently and is still somewhat tenuous.

Figure l.
Location of Ash Meadows, Nye County,Nevada, and Inyo
County, California (modified from Soltz and Naiman 1978).

[1] Paper presented at the California Riparian Systems Conference. [University of California, Davis, September 17–19, 1981].

[2] Cynthia D. Williams is Graduate Teaching Assistant, Department of Biological Sciences, California State University, Sacramento.

[3] Deacon, J.E. Professor of Biology, University of Nevada, Las Vegas. Personal communication.

Figure 2.
Crystal Spring is one of the largest springs in the Ash Meadows area, with a discharge rate
of 10,741 LPM (Mifflin 1968). Note the extensive riparian zone surrounding the spring.

Species Accounts

Ash Meadows has the highest amount of biological endemism of any area in the United States. More than 25 organisms—including eight plants, two insects, 10 or more molluscs, five fishes, and one mammal—are endemic to Ash Meadows (table 1). Only one other arid region of North America, the Cuatro Cienegas Basin of northeastern Mexico, supports a greater diversity of endemic organisms (Minckley 1969).

Three of the endemic plants, Astragalusphoenix , Mentzelialeucophila , and Nitrophila mohavensis , are official candidates for inclusion on the federal list of threatened and endangered species. An additional two species and several varieties of plants are also endemic to the Ash Meadows area.

There are more than 10 snail species, including four species of an undescribed "Nevada Spring Snail" genus and approximately six species of Tryonia , endemic to springs in Ash Meadows. These snails are all candidates for federal listing. Ambrysusamargosus , a naucorid restricted to Ash Meadows, is also a candidate species.

Five fishes are endemic to Ash Meadows. The Ash Meadows killifish, Empetrichthysmerriami , was last seen in 1948 (Soltz and Naiman 1978). Apparently, E . merriami was a casualty of competition and predation by exotic organisms. Historically, this species occupied most of the large, lower-elevation springs. Three pupfish are endemic to Ash Meadows. The Devil's Hole pupfish, Cyprinodondiabolis , is restricted to Devil's Hole, a disjunct part of Death Valley National Monument, which encompasses 1.6 ha. (4 ac.) of the Ash Meadows system. This species of pupfish has undergone significant evolutionary changes (e.g., loss of pelvic fins) during its long period of isolation and is very distinct from its closest relative. In recognition of the precarious existence of C . diabolis , it is listed as endangered by the USDI Fish and Wildlife Service (FWS). The two Ash Meadows subspecies of Amargosa pupfish, Cyprinodonnevadensispectoralis and C . n . mionectes , inhabit the mid-level and lower springs, respectively. Cyprinodon n . pectoralis is listed as endangered by the FWS, and C . n . mionectes is an official candidate. A form of speckled dace, Rhinichthysosculusnevadensis , which inhabits many of the lower-

elevation springs is also a candidate to the list of federally protected species.^[4]

The flora and fauna of Ash Meadows represent a unique and threatened biota, including two extinct and over 25 extant endemics. Many of the extant endemics have received official recognition of their precarious status, and such recognition is pending for many more.

Threats to the Ecosystem

Prior to the coming of the white man, Ash Meadows was apparently heavily utilized by several Indian cultures. This unobtrusive use of Ash Meadows came to an abrupt end at the beginning of the twentieth century. The first detrimental use of the area by man occurred from 1910 to 1930 when Carson Slough, an extensive marsh system in the western part of Ash Meadows, was drained for mining peat and clay. The mid-1940s saw man's continuing impact on the Ash Meadows ecosystem in the introduction of bullfrogs and crayfish to springs in Ash Meadows. Several shifts in abundance of native fishes at that time have been attributed to those introductions (Miller 1948). Since the 1940s a variety of tropical fish and a snail, Melanoidestuberculatum , have been added to the growing list of exotic species in the area (Hardy 1980).

During the late 1960s, Spring Meadows Ranch began extensive groundwater pumping for irrigation, and the water level in Devil's Hole began to decline, reaching an all-time low in 1972. The USDI National Park Service (NPS) began formal court proceedings in 1971 in an effort to protect both the Devil's Hole pupfish and the special geologic character of the limestone cavern in

[4] By emerging rule, the FWS declared Ash Meadows pupfish and the Ash Meadows speckled dace to be endangered species on 10 May 1982. This temporary ruling is in force for 240 days.

which the species resides. A preliminary injunction in 1973 established a minimum level below which water in Devil's Hole could not fall. The case was finally heard in the US Supreme Court, which, on 7 June 1976, established a minimum water level that is considered consistant with the continued survival of the pupfish (Deacon and Deacon 1979).

Subsequent to the Supreme Court decision the Spring Meadows Ranch was put up for sale, and was purchased by Preferred Equities Corporation. Preferred Equities currently owns about 5,665 ha. in the heart of Ash Meadows and most of the water rights. Plans have been completed for three major developments that include parcels for high density trailer lots, single family residences, and commercial areas.

In addition to the current threat from Preferred Equities Corporation, Ash Meadows is now facing pressure from mineral development. In 1980, Anaconda Copper Company purchased property near Big Spring with plans to expand a zeolite mining operation. The zeolite deposit extends northward from the currently worked area toward the center of Ash Meadows. Further to the northwest, Tenneco is mining and processing borax.

Management

Without a doubt, the recent industrial, residential, and mineral development schemes threaten to bring about the demise of the Ash Meadows ecosystem. The planned developments would greatly increase the number of people living and working in the area. In 1980, approximately 15 people lived in Ash Meadows. Preferred Equities' plans for 33,000 homes, and a high density trailer court would dramatically increase that number.

Increased population would result in a variety of direct and indirect impacts. A large amount of land would have to be cleared and leveled to provide homesites and many new roads would have to be built. Several springs would be physically altered for recreational purposes. Plans exist to build a health spa around Crystal Spring and a reservoir over Point-of-Rocks Springs. The incidence of exotic species introduction can be expected to increase with the growing human population. Similarly it can be expected that the native aquatic organisms will be transferred from spring to spring without regard to their historical ranges. Groundwater depletion could once again become a critical problem. Development of the magnitude envisioned by Preferred Equities Corporation would require vast amounts of water for which an adequate supply is questionable.

Ash Meadows presents the opportunity for one of the very few "all or nothing" management decisions. We must make the philosophical decision of whether or not Ash Meadows and its inhabitants are worth saving. If we decide that the Ash Meadows ecosystem should be preserved in perpetuity, federal or state acquisition and subsequent incorporation into a federal or state refuge becomes the only alternative. A vehicle for this action exists in the form of Senate Bill 41, introduced in the ninety-seventh Congress by Senator Alan Cranston. If passed this bill would authorize the establishment of a Desert Pupfish National Wildlife Refuge in Ash Meadows. Sound management of a refuge thus established could allow for protection of the ecosystem with leeway for some mineral development. Regardless of the outcome of S.B. 41, the protections, inherent in the National Monument System, which are now being applied to Devil's Hole should continue to be fully applied.

Acknowledgments

The manuscript was reviewed by Jack E. Williams of the FWS, who is thanked for his most helpful comments. James E. Deacon of the University of Nevada, Las Vegas, provided information on paleohydrology, but perhaps more importantly instilled in me an appreciation of the Ash Meadows ecosystem.

Literature Cited

Deacon, J.E., and M.S. Deacon. 1979. Research on endemic fishes in the National Parks with special emphasis on the Devils Hole pupfish. USDI National Park Service Trans. and Proc. Ser. 5:9–19.

Hardy, T. 1980. The Inter-basin area report—1979. Proc. Desert Fishes Council 11:5–21.

Mifflin, M.D. 1968. Delineation of ground-water flow systems in Nevada. Desert Res. Inst., Center for Water Resources Research Tech. Rep. H-W, No. 4. University of Nevada, Reno. 110 p.

Miller, R.R. 1948. The cyprinodont fishes of the Death Valley system of eastern California and southwestern Nevada. University of Michigan, Mus. Zool. Misc. Publ. 68:1–155.

Minckley, W.L. 1969. Environments of the bolson of Cuatro Cienegas, Coahuila, Mexico. University of Texas, El Paso Sci. Ser. 2:1–65.

Snyder, C.T., G. Hardman, and F.F. Zdenek. 1964. Pleistocene lakes in the Great Basin. USDI Geological Survey, Misc. Geol. Investigations, Map I-416.

Soltz, D.L., and R.J. Naiman. 1978. The natural history of native fishes in the Death Valley system. Nat. Hist. Mus. of Los Angeles Co., Sci. Ser. 30:1–76.