Rare, Threatened or Endangered Species

White Bluffs Bladderpod

The Portland Oregonian newspaper once called the Hanford Site "a nuclear Yellowstone, patrolled by park rangers armed with submachine guns and night vision goggles." For the most part, the armed guards are gone, at least from the areas within the Monument, but the legacy of war-time secrecy and almost seven decades of unintended preservation has left Hanford as a stronghold for several rare, threatened, or endangered plants and animals.

The Endangered Species Act (ESA) provides protection and recovery efforts for plant and animal species listed as threatened or endangered. The species listed under the ESA known to exist on the Monument include the upper Columbia River steelhead (endangered) and spring-run Chinook salmon (endangered). The Columbia Basin pygmy rabbit was emergency listed as federally endangered in November 2001; however, they are likely extirpated from the Monument.

Other federally listed species have been reported in very rare instances on or near the Hanford Site. The bull trout, a state candidate species and federal threatened species, has been reported in the Hanford Reach, but its natural habitat is mountain streams; anecdotal accounts of bull trout in the Hanford Reach are likely individuals moved downstream during the spring freshet. The Washington ground squirrel, listed as a candidate species by both the state and federal governments, has been documented just north of the crest of the Saddle Mountains.

The Monument is also home, at least at times, to a couple of species no longer considered threatened or endangered at the federal level. Peregrine falcons are occasionally seen in the Hanford Site during migration, but are no longer listed as a state or federal endangered species. The bald eagle was considered a federally threatened species in the state of Washington; it is considered ‘recovered’ and has been removed from the endangered species list. The bald eagle is a regular winter resident and forages primarily on waterfowl and spawned salmon along the Columbia River; an average of forty eagles use the Hanford Reach each winter. Bald eagles have not nested along the Hanford Reach, although for the last several years unsuccessful nesting attempts have been documented. Access controls are in place along the river while eagles are present to prevent their disturbance.

There are three plants on the Monument that are very rare. These include . . .

Unique Plants


The persistent-sepal yellowcress is proposed for listing under the Endangered Species Act. The Umtanum desert buckwheat and White Bluffs bladderpod were listed as threatened under the ESA on December 20, 2013. One additional species, northern wormwood, is a candidate for listing, and although there are no known occurrences on the Hanford Site, The Nature Conservancy believes islands in the Hanford Reach could support populations.

The White Bluffs bladderpod and the Umtanum desert buckwheat are species discovered on the Hanford Site and are not known to exist anywhere else. Another plant, the Rattlesnake mountain milk-vetch, is a variety of milk-vetch also unique to the Hanford Site.


Rattlesnake Mountain Milkvetch (Basalt Milkvetch)


Rattlesnake Mountain milkvetch, variety rickardii, a relatively common milkvetch on the north-facing slopes and summit of Rattlesnake Mountain, has been determined to be a new variety. For many years prior to this determination it was mistakenly referred to as the variety reventiformis (Yakima milkvetch). On the Monument, the milkvetch is scattered in bunchgrass areas along the main ridges of Rattlesnake Mountain where the population includes several tens of thousands of plants. However, the population remains incompletely mapped. The two known locations of the plant are both in Benton County—the large population on Rattlesnake Mountain and a small population in the Chandler Butte portion of the Horse Heaven Hills. The Monument’s population is entirely within the boundaries of the ALE, where it benefits from very limited access and low disturbance. Maintenance of public ownership and current access levels are the most likely methods to ensure the long-term survival and viability of this plant.


Umtanum Desert Buckwheat


The buckwheat is a woody plant, with some individual plants estimated to be well over 100 years old. This species was first described on the Monument in 1995. Currently, it is listed as endangered by the state of Washington and threatened by the federal government. Despite some mortality from a fire in 1996, there is an estimated population of 5,200 plants. Several state-listed species—Hoover’s desert-parsley, Columbia milk-vetch, and Piper’s daisy—occur within the vicinity of the newly discovered population, as does a population of Great Basin gilia, previously not known in Washington.

Umtanum desert buckwheat appears to be restricted to a discontinuous mile-long strip generally less than 100-feet wide weathered basalt outcrop on the top edge of the Umtanum Ridge in Benton County. This is within an area receiving little use and is officially not accessible to the public. However, fences in the area are regularly cut and trespassing occurs. A portion of the site has visible petrified wood, and there are signs of collecting within the buckwheat population. It is also threatened by fire, invasive species, off-road vehicle destruction and stray cattle. Long-term demographic monitoring was initiated on this species in 1997.

Federal Register Notice Listing Umtanum Desert Buckwheat as Threatened (518 MB PDF) 


White Bluffs Bladderpod


The White Bluffs bladderpod is a showy flowering perennial limited to the White Bluffs area of the Hanford Reach. This species was first described on the Hanford Site in 1994. It is listed as threatened by the state of Washington and the federal government. The total count of adult plants in 1997 was estimated to be 50,000 plants spread across an eight-mile-long occurrence. Several other rare plant populations exist in the immediate area, including dwarf evening primrose, Piper’s daisy, Snake River cryptantha, and desert dodder.

The White Bluffs are a unique exposure of the Ringold Formation; the bluffs are made of soft Pliocene lacustrine deposits of clay, sand and silt. The top is capped in many places by a harder calcium carbonate (caliche) layer. White Bluffs bladderpod appears to be restricted to this caliche layer. Most of the population is outside the Hanford Reach corridor (technically 0.25 mile on either side of the river).

The primary threats to the bladderpod population are fire, ORV use, erosion, conversion of habitat, weed invasions, or slumping of the bluffs due to illegal ORV use or irrigation. Infestations of yellow starthistle, a noxious weed, are located within the middle portion of the bladderpod population. The protection of this population, and thus the species, requires that these issues be addressed in any management action. Long-term demographic monitoring was initiated on this species in 1997.

Federal Register Notice Listing Umtanum Desert Buckwheat as Threatened (518 MB PDF)