A fish tale: a small fish, the ESA, and our shared future.

AuthorGoble, Dale D.

I.

The Borax Lake chub (Gila boraxobius) is a small fish (typically 1.3 to two inches in length) that is dark olive-green above and mostly silver below with a hint of purple iridescence. (1) It is an opportunistic omnivore, feeding on whatever comes its way: aquatic and terrestrial insects, spiders, mollusks and their eggs, aquatic worms, algae, and seeds. (2) The species reaches reproductive maturity within a single year. (3) Although it spawns primarily in the spring, breeding can occur throughout the year. (4)

The chub takes its name from the environment that created it: Borax Lake, a small (10.2-acre), shallow (less than three feet), highly mineralized, alkaline lake in the Alvord Basin of eastern Oregon's high desert. (5) Borax Lake, which is fed by subterranean hot springs, is an unusual ecosystem, in part because it is a "perched" lake: Precipitation of minerals from the water over the millennia has raised the lake's shoreline approximately thirty feet above the salt crust that covers the adjacent desert playa. (6) Water overflowing the lake's southwest rim has created an extensive marsh that ends in the small, intermittent Lower Borax Lake. (7)

The springs flowing into the lake have temperatures between 95 and 104 degrees Fahrenheit ([degrees]F). (8) The chub prefers water of 84[degrees]F to 86[degrees]F, and temperatures above 93[degrees]F are potentially lethal. (9) The chubs therefore live around the shallow perimeter of the lake and in the wetlands at the lake's outflow where the temperature is within their preferred range. (10) This further reduces the available habitat to only a fraction of the lake's area and makes the species particularly vulnerable to decreases in water level. (11)

During the Pleistocene, the floor of the A1vord Basin was covered by Lake Alvord, a large pluvial lake that was the ancestral home of the chub. (12) The level of Lake A1vord has fluctuated greatly over at least the past 40,000 years. (13) Within the last 10,000 years it largely dried up, leaving only two intermittent remnants: Alvord Lake in Oregon and Continental Lake in Nevada. (14) The retreat of Lake A1vord restricted the lake's fish to scattered populations in the few permanent springs and creeks that remained. (15)

Prior to 1980, the Borax Lake chub had been considered a dwarfed population of the Alvord chub (Gila alvordensis), the species found elsewhere in the Alvord Basin. (16) Isolation from other populations of the Alvord chub, plus a combination of extreme environmental conditions, short generation times in the warm water, and the small number of founding individuals, led to a rapid differentiation of the population into what is now acknowledged to be a distinct, endemic species--the Borax Lake chub. (17)

II.

The purpose of the Endangered Species Act (ESA) (18) is to "conserve" species at risk of extinction and the ecosystems upon which these species depend. (19) This is more than a requirement simply to prevent extinction. "Conserve" is defined as the affirmative mandate to "use ... all methods and procedures which are necessary to bring any [listed] species ... to the point at which the measures provided pursuant to this [Act] are no longer necessary." (20) Conservation, in other words, requires the recovery of listed species. To achieve this goal, the Act's drafters crafted what they envisioned to be an orderly progression that moves from assessing the threats facing a species, through the elimination of those threats, to recovery and delisting. (21)

The threshold to this progression is a risk assessment. The federal agencies responsible for implementing the Act are required to determine whether a species is either endangered or threatened based on a set of enumerated threats. (22) The Act defines "endangered species" as "any species which is in danger of extinction throughout all or a significant portion of its range." (23) The definition of "threatened species" differs only through the addition of an explicit temporal component: a threatened species is "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." (24) These standards are none too precise: The statutory definitions require the decision maker to determine whether a species is to be listed given its risk of extinction (i.e., "in danger of extinction, or likely to become so" (25)) over a temporal scale (i.e., now or "within the foreseeable future" (26)).

The species's status as endangered, threatened, or insufficiently at risk to warrant listing is determined by assessing five threat factors: 1) habitat destruction or range curtailment, 2) overutilization, 3) disease or predation, 4) inadequate regulatory mechanisms, and 5) any "other natural or manmade factors." (27) If the agency concludes that a species is either threatened or endangered, it is required to list the species. (28)

Listing triggers the ESA's risk-management provisions. (29) These can be divided in to two functional groups. The first is extinction prevention, a group of tools--primarily restrictions on actions such as the prohibition on taking an endangered species--intended to protect a listed species from activities that threaten its continued existence. (30) The second group of risk-management provisions are recovery actions. These are a far more varied group of affirmative statutory tools intended to address the threats facing a species; they include mechanisms such as the authority to transplant populations or restore habitat. (31)

The drafters of the ESA appear to have assumed that recovery actions would eliminate the threats facing the species and that its population would rebound. When this occurred, the listing agency would initiate delisting, employing the same risk-assessment standards and procedures used in the decision to list the species. (32) The Act's drafters also appear to have assumed that after delisting the species would thrive with only existing management, such as state fish and game laws.

Implementing the Act has proved more complex--as the tale of the Borax Lake chub demonstrates.

III.

In 1980, as the paper characterizing the chub as a new species was in the editorial process, (33) two activities around Borax Lake were imperiling the species's continued existence. First, the rancher who owned the lake and the surrounding 160 acres cut channels into its perimeter to irrigate forage on his land. (34) In addition to lowering the lake level, the channels redirected the flow of water from the lake's natural outflow, drying up the wetlands and Lower Borax Lake. (35) Second, the agency that managed the federal land adjacent to the lake, the Bureau of Land Management (BLM), began the process of issuing leases to permit the geothermal development of the Alvord Basin. (36)

In response to BLM's proposal to lease 6789 acres surrounding Borax Lake for geothermal exploration and testing, the United States Fish and Wildlife Service (FWS) promulgated an emergency regulation listing the chub as an endangered species on May 28, 1980. (37) The agency's rationale for listing the species focused on the threats to its habitat. The lake's "position above the valley floor," FWS noted, made it vulnerable to the irrigation diversions that both lowered the level of the lake and diverted water away from the natural outflow. (38) Geothermal exploration also threatened the species given the potential changes to the subsurface flow of water in the aquifer that fed the lake. (39) The listing was necessary, the agency concluded, to ensure that BLM considered "the welfare of this species during its deliberations" on both the leasing decision and the stipulations that would be included in any leases that it might eventually issue. (40)

With the listing of the species, the Act's extinction prevention and recovery action provisions became applicable. The extinction prevention requirements came into play first given their prohibitory orientation. (41) The Act requires any federal agency whose actions are likely to affect a listed species to consult with the appropriate federal wildlife agency--in the case of the chub, FWS--to "insure" that the action "is not likely to jeopardize the continued existence of [the species] ... or result in the destruction or adverse modification" of the species's critical habitat. (42) Because the exploration activities permitted by proposed geothermal exploration leases could affect the chub, BLM requested formal consultation with FWS on July 3, 1980. (43) Following several exchanges of documents and a meeting in September that was attended by FWS, the United States Geological Survey, BLM, Anadarko Production Company, Getty Oil, several state agencies, two private utilities, "and various environmental and engineering consulting firms," (44) FWS issued a biological opinion (BiOp) evaluating the risk the leasing action posed to the chub. (45) The BiOp concluded that granting "geothermal exploration leases, with present stipulations, for BLM Leasing Units 28, 33 and 34 is likely to jeopardize the continued existence of the Borax Lake chub and/or adversely modify its critical habitat." (46) "[T]he key issue of concern," the BiOp noted, "is the likelihood that drilling activity might impact th[e] fault system" beneath the basin floor that is the source of both the thermal springs that feed the lake and the cold water aquifer that reduces the temperature of the springs to a range that the chub can withstand. (47)

When FWS issues a "jeopardy" opinion, the ESA requires the agency to provide "reasonable and prudent alternatives" to the action that would permit it to proceed without jeopardizing the species. (48) At the September meeting, the participants agreed that a half-mile buffer around the lake and the associated hot springs "would probably provide adequate protection to the aquifers." (49) FWS therefore recommended that any leases include a half-mile...

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