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Life History Information for Species and Critical Habitats Associated with CRB Water Bodies

This section contains additional life history information on Endangered Species Act listed species in the Columbia River Basin. These species likely would not be affected by a dreissenid control action using the methods included in this toolkit and following best management practices.
Mammals: Columbian white-tailed deer
Birds: Least Tern | Piping plover | Red knot | Western snowy plover | Yellow-billed cuckoo
Amphibians: Spotted frog
Invertebrates: Banbury Springs limpet | Bliss Rapids snail | Snake River Physa snail
Plants: Bradshaw's desert parsley | Nelson's checker-mallow | Ute ladies'-tresses | Water howellia | Willamette daisy
Also listed in the fish section is additional information on key CRB fish species. These species would likely experience effects from a control action:
Fish: Bull trout | Kootenai River white sturgeon |Lahontan cutthroat trout 


Columbian white-tailed deer (Odocoileus virginianus leucurus) (OR, WA)

Information provided here is summarized in USFWS (1983) and from USACE and USFWS (2018).

Listing History

On March 11, 1967, the Secretary of the Interior identified the Columbian white-tailed deer (CWTD) as an endangered species under the authority of the Endangered Species Preservation Act of October 15, 1966. On March 8, 1969, the Secretary of the Interior again identified the CWTD as an endangered species. On August 25, 1970, the Acting Secretary of the Interior proposed to list the CWTD as an endangered subspecies under the authority of new regulations implementing the Endangered Species Conservation Act of 1969. The CWTD was automatically listed under the ESA when it was enacted in 1973.


On July 24, 2003, the Douglas County, Oregon, population was delisted due to recovery. October 17, 2016, the USFWS published a final rule to “downlist” the CWTD to threatened status.


Life History/Biological Requirements

Islands and bottomlands along the lower Columbia River around 9.8 ft (3 m) above sea level with vegetation over 2.3 ft (0.7 m) high in the vicinity of forage species are preferred. Native vegetation of the Columbia River tidal area includes dense, tall shrub and tree community including Sitka spruce, dogwood, cottonwood, red alder, and willow species. These and other species such as rose, sumac, and elderberry are common food and cover sources.

Breeding occurs from mid-September through late February, with a peak in November. Does reach sexual maturity by 6 months of age or when their weight reaches approximately 2.2 pounds [lbs (36 kilograms (kg))]. Maturation and fertility depends on the nutritional quality of available forage. Fawns are born in early summer after a 200-day gestation period.


Distribution and Critical Habitat

Columbian-white tailed deer are associated with riparian habitats in the Lower Columbia River and Douglas County, Oregon.[1] This species occupies tidal spruce habitats—densely forested swamps covered with tall shrubs and scattered spruce, alder, cottonwood, and willows—on islands along the Columbia River. Islands and bottomlands along the lower Columbia River around 9.8 ft (3 m) above sea level with vegetation over 2.3 ft (0.7 m) high near forage species are preferred. Native vegetation of the Columbia River tidal area includes dense, tall shrub and tree community including Sitka spruce, dogwood, cottonwood, red alder, and willow species. These and other species such as rose, sumac, and elderberry are common food and cover sources.


In Douglas County, Oregon, this species uses willow and cottonwood habitat along rivers and streams as well as oak-savannah habitats in upland areas.


Although habitat types and locations have been identified for the Columbian white-tailed deer, no critical habitat has been designated. Currently, the Columbia River DPS has a discontinuous range of approximately 149 mi² (240 km²) or about 60,000 ac² (24,281 ha²) in limited areas of Clatsop, Multnomah, and Columbia Counties in Oregon, and Cowlitz, Wahkiakum, Pacific, Skamania, and Clark Counties in Washington. Within that range, CWTD currently occupy an area of approximately 16,000 ac² [6,475 ha²].



Conversion of brushy riparian land to agriculture, urbanization, uncontrolled sport, commercial hunting, and other factors caused the extirpation of CWTD over most of its range. A lack of dense woody cover between open pastures has been identified as a major limiting habitat factor. The population had also been severed into two small, spatially separated groups, historically, making genetic diversity another risk factor.

Other potential threats include catastrophic flood damaging suitable habitat, as well as hoof rot, which is a crippling hoof disease exacerbated by wet conditions that has plagued the Columbia River population.






Least tern (Sterna antillarum) (MT)

Information provided here is summarized in USFWS (1990) and from USACE and USFWS (2018).

Listing History

The interior least tern was listed as an endangered species on June 27, 1985 in the States of Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana (Mississippi River and its tributaries north of Baton Rouge), Mississippi (Mississippi River), Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Tennessee, and Texas (except within 80 km of Gulf Coast).

Life History/Biological requirements

Interior least terns spend about 4-5 months at their breeding sites. They arrive at breeding areas from late April to early June. Courtship behavior of least terns is similar throughout North America. Courtship occurs at the nesting site or at some distance from the nest site. Breeding site fidelity is high.


From late April to August they occur primarily on barren to sparsely vegetated riverine sandbars, dike field sandbar islands, sand and gravel pits, and lake and reservoir shorelines. The nest is a shallow and inconspicuous depression in an open, sandy area, gravelly patch, or exposed flat. Small stones, twigs, pieces of wood and debris usually lie near the nest. Least terns nest in colonies or terneries, and nests can be as close as just a few meters apart or widely scattered up to hundreds of meters.


The birds usually lay two or three eggs. The average clutch size for interior least terns nesting on the Mississippi River during 1986–1989 was 2.4 eggs. Egg-laying begins by late May. Both sexes share incubation which generally lasts 20-25 days, but has ranged from 17 to 28 days.


The interior least tern’s home range during the breeding season usually is limited to a reach of river near the sandbar nesting site where they feed primarily on fish.

Distribution and Critical Habitat

No critical habitat has been designated for the interior population of the least tern. The interior least tern is migratory and historically bred along the Mississippi, Red and Rio Grande River systems and rivers of central Texas. The breeding range extended from Texas to Montana and from eastern Colorado and New Mexico to southern Indiana. It included the Red, Missouri, Arkansas, Mississippi, Ohio and Rio Grande River systems. Incidental occurrences of least terns in Michigan, Minnesota, Wisconsin, Ohio and Arizona have been reported. Any sightings of least terns within the Columbia River Basin would be deemed accidental because the CRB is well outside the range of this species (Institute for Natural Resources, personal communication).


The interior least tern continues to breed in most of the aforementioned river systems, although its distribution generally is restricted to less altered river segments.


Least terns nest on barren to sparsely vegetated sandbars along rivers, sand and gravel pits, lake and reservoir shorelines, and occasionally gravel rooftops. Recreational activities on rivers and sandbars disturb nesting least terns, causing them to abandon their nests. The interior least tern breeding season is April through August – nesting season is mid-May through August. Nesting in small colonies, least tern nests are shallow depressions scraped in open sandy areas, gravelly patches, or exposed flats. Both parents incubate their eggs for about 24 days. Chicks leave the nest only a few days after hatching, but the adults continue to care for them, leading them to shelter in nearby grasses and bringing them food. The interior least tern’s home range during the breeding season usually is limited to a reach of river near the sandbar nesting site where they feed primarily on fish.



Threats to the survival of the species include the actual and functional loss of riverine sandbar habitat. Channelization and impoundment of rivers have directly eliminated nesting habitat.

Piping plover (Charadrius melodus) (MT)

Information provided here is summarized in Atkinson and Dood (2006).

Breeding Season Habitat

In north-central North America, plovers typically nest on barren sand and gravel beaches along the Great Lakes, and on alkali flats, gravel shorelines and river sandbars in the Great Plains (USFWS 2002c). While data suggests that habitat use by plovers is dynamic (USFWS 2002c), alkali lakes and wetlands associated with the Missouri Coteau landform, located inside the Prairie Pothole Region, appear to support a significant portion (34 -75%) of the Great Plains population in any given year (Haig and Plissner 1993, Murphy et al. 2000, Plissner and Haig 2000, Haig et al. 2005, Skagen and Thompson 2005). Remaining nest sites occur primarily along rivers and reservoirs although fresh water lakes, dry alkali lakes, sandpits, industrial ponds and gravel mines may also be utilized (Haig et al. 2005).


Piping plovers are a migratory species. Piping Plovers primarily select unvegetated sand or pebble beaches on shorelines or islands in freshwater and saline wetlands. Vegetation, if present at all, consists of sparse, scattered clumps (Casey 2000). Open shorelines and sandbars of rivers and large reservoirs in the eastern and north-central portions of Montana provide prime breeding habitat. In Montana, and throughout the species' range, nesting may occur on a variety of habitat types. If conditions are right, alkali wetlands, lakes, reservoirs, and rivers can all provide the essential features required for nesting. The alkali wetlands and lakes found in the northeastern corner of the state generally contain wide, unvegetated, gravelly, salt-encrusted beaches. Rivers that flood adequately can supply open sandbars or gravelly beaches, as can large reservoirs, with their shoreline beaches, peninsulas, and islands of gravel or sand. Sites with gravel substrate provide the most suitable sites for nesting (Montana Piping Plover Recovery Committee 1994). One of the most limiting factors to nesting site selection is vegetational encroachment. Piping Plovers avoid areas where vegetation provides cover for potential predators. Fine-textured soils are easier to treat mechanically than rocky or gravelly soils when vegetation is determined as a limiting factor in an area's ability to provide suitable nesting habitat, but fine soils are not typically a preferred nesting substrate (Montana Piping Plover Recovery Committee 1994). Nests are simple scrapes dug into the nest substrate which may or may not be lined with pebbles (Montana Piping Plover Recovery Committee 1994, 1995, Haig 1992).


Migrants begin arriving at breeding areas in southern Washington in early March and in central California as early as January, although the main arrival is from early March to late April. Since some individuals nest at multiple locations during the same year, birds may continue arriving through June. Males make a nest scrape, which is a depression in the sand or substrate made by leaning forward on his breast and scratching his feet while rotating his body axis. The earliest nests on the California coast occur during the first week of March in some years and by the third week of March in most years. Peak initiation of nesting is from mid-April to mid-June. Hatching lasts from early April through mid-August, with chicks reaching fledging age approximately 1 month after hatching.


Riverine Habitat

Characteristic riverine nesting sites include reservoir beaches and large dry, barren sand or gravel bars within wide, unobstructed river channels (USFWS 1988). Nests are usually located after the spring and early summer flows recede and dry areas on sandbars are exposed. Along the Platte River, Nebraska, relatively large sandbars, averaging 286 m long and 55 m wide, appear to be selected when available (Faanes 1983). In addition, preferred vegetative cover at nest sites is generally low (Schwalbach 1988). Although Faanes (1983) reported vegetative cover of 25% on nesting sandbar habitat along the Platte River, other research suggests that the optimum range is much lower: estimates range from 0-10% (Armbruster 1986). Likewise, along the Missouri River in South Dakota, plover colony sites were characteristically barren or with short (<10cm) sparse (<10%) vegetative cover (Schwalbach 1988).

Foraging Habitat
Plovers feed by pecking at or just below the substrate surface (Cairns 1977, USFWS 2002c, Haig and Elliot-Smith 2004) and require feeding grounds that are rich in surface invertebrates (Shaffer and Laporte 1994). While adults typically concentrate feeding efforts within 5 m of the water’s edge (Whyte 1985), chicks tend to feed on firmer ground at greater distances from the shoreline (Cairns 1977).


Critical Habitat

In 2002, the USFWS officially designated critical habitat for the Northern Great Plains breeding population (USFWS 2002c). Under the Endangered Species Act, critical habitat refers to specific geographic locations that contain features essential for conserving a species and may require special management considerations. While critical habitat can be, and is, designated on private lands, it only relates to those activities on private lands that require federal permits or funding that are required to be reviewed under the Act. For piping plovers, primary constituent elements include components essential for courtship, breeding, sheltering, brood-rearing, foraging, roosting, intraspecific communication and migration. Furthermore, it stated that the one overriding primary biological element that must be present at all sites is the maintenance of the dynamic ecological processes that create and maintain piping plover habitat.


On prairie alkali lakes and wetlands the physical primary constituent elements include shallow, seasonally to permanently flooded, wetlands with sandy to gravelly, sparsely vegetated beaches as well as springs and fens along the edges of alkali lakes and wetlands. Along rivers, sparsely vegetated channel sandbars, sand and gravel beaches on islands and temporary pools on sandbars are considered primary. At reservoirs and inland lakes such elements include sparsely vegetated shoreline beaches, peninsulas, islands composed of sand and gravel or shale and their interface with the water bodies.

In its final ruling, the USFWS identified a total of 19 habitat units in the states of Minnesota, Montana, Nebraska, North Dakota, and South Dakota as critical to aiding piping plover recovery (USFWS 2002c).

Within Montana, 40,423.1 hectares (99,887.5 acres) including four separate units comprised of various ownership patterns are designated as critical habitat (Table 7).

Table 7. Land ownership within unit boundaries for critical piping plover habitat in Montana. Source: USFWS (2002).

Least Tern
Piping plover
Anchor 1

* Ownership of sites along the Missouri River varies by state. In Montana, islands and sandbars are recognized as owned by the State except along the reservation boundaries of the Assiniboine and Sioux Tribes of Fort Peck; tribes own land to the mid-channel of the Missouri River adjacent to the Reservation boundary.

Sheridan County (Unit MT-1), in the extreme northeastern corner of the state, includes 20 alkali lakes and wetlands. Essential nesting habitat is dispersed throughout this unit. The Missouri River units (MT-2 and MT-3) consist of both reservoir and river reaches: Fort Peck Reservoir is located entirely within the Charles M. Russel NWR, while unit MT-2 encompasses approximately 201.8 km of the Missouri River just west of Wolf Point to the Montana-North Dakota border.


The river reach below Fort Peck Reservoir to the confluence of the Milk River is not included as it is highly degraded and contains few sandbars. Bowdoin NWR is the site of the fourth critical habitat unit (MT-4). Despite sporadic breeding records at Alkali Lake in Pondera County, Bowdoin NWR, located in east-central Phillips County, represents the typical western edge of the Northern Great Plains breeding population of piping plovers.


In Phillips County, three historic lake beds at Nelson Reservoir most likely provided essential habitat to breeding piping plovers however this area was flooded when the reservoir was created for irrigation purposes. While Nelson Reservoir was originally proposed for critical habitat inclusion, it was excluded from the final listing as a Memorandum of Understanding (MOU) between the Bureau of Reclamation

(BOR), the USFWS, and local Irrigation Districts was in place that would minimize the threat of flooding to active piping plover nest sites. Additionally, as part of the terms and conditions of a 1990 biological opinion on the operation of Nelson Reservoir by the BOR, conservation measures had been employed to minimize take, and would continue.


Occupied nesting habitat on North Alkali Lake in Pondera County occurs on Blackfeet tribal land and was not designated critical habitat at the request of the tribal government. Habitat on tribal lands determined essential to conserve the species may be designated. This was the case for sand bars along the Missouri River along the Fort Peck Reservation. The USFWS believes this designation is consistent with the special trust responsibility the Federal government has to Indian people to preserve and protect their lands and resources.


In Montana, spring arrival of the species most often occurs from late April through early May with departure occurring by late August (Montana Piping Plover Recovery Committee 1997). Recent analysis of migration data from banded Great Lakes birds suggests that critical habitat units are used heavily during migration (Stucker and Cuthbert 2006). Further, while stopover length could not be quantified in this study the authors speculate that it may be variable in length for the Great Lakes population, ranging from several days to one month based on anecdotal reports (Stucker and Cuthbert 2006).



Figure 5. Summer range (green) and migratory range (yellow) of piping plovers in Montana. Source. Montana Natural Heritage Program.

Red knot
Red knot (Calidris canutus rufa) (MT)

Red knots are a migratory species. Migratory stopovers in Montana are rare, but are most common at larger wetlands. A total of 60 percent of documented migratory stopovers in Montana have been at Freezeout Lake, Benton Lake National Wildlife Refuge, and Lake Bowdoin National Wildlife Refuge (Montana Natural Heritage Program Point Observation Database 2016). Red knots are rarely observed at Montana wetlands during migration in May or July through October (Montana Natural Heritage Program Point Observation Database 2016). There are only about 50 observations documented for individuals stopping at Montana wetlands, with only 0–4 for any given year since the 1970s; 60 percent of observations have been in May associated with northward migration (Montana Natural Heritage Program Point Observation Database 2016).


Western snowy plover (Charadrius alexandrines nivosus) - Pacific Coast Population (OR, WA)

Information included here is from USFWS (2007) and USACE (2018).

Listing History

On March 5, 1993, the Pacific coast population of the western snowy plover was listed as threatened. The Pacific coast population is defined as those individuals that nest within 50 mi (80.5 km) of the Pacific Ocean on the mainland coast, peninsulas, offshore islands, bays, estuaries, or rivers of the United States and Baja California, Mexico.

Life History/Biological requirements

The Pacific coast population of the western snowy plover breeds primarily above the high tide line on coastal beaches, sand spits, dune-backed beaches, sparsely-vegetated dunes, beaches at creek and river mouths, and salt pans at lagoons and estuaries. Less common nesting habitats include bluff-backed beaches, dredged material disposal sites, salt pond levees, dry salt ponds, and river bars.


Migrants begin arriving at breeding areas in southern Washington in early March and in central California as early as January, although the main arrival is from early March to late April. Since some individuals nest at multiple locations during the same year, birds may continue arriving through June. Males make a nest scrape, which is a depression in the sand or substrate made by leaning forward on his breast and scratching his feet while rotating his body axis.


The earliest nests on the California coast occur during the first week of March in some years and by the third week of March in most years. Peak initiation of nesting is from mid-April to mid-June. Hatching lasts from early April through mid-August, with chicks reaching fledging age approximately 1 month after hatching.


In winter, western snowy plovers are found on many of the beaches used for nesting as well as on beaches where they do not nest, in man-made salt ponds, and on estuarine sand and mud flats.


Distribution and Critical Habitat

Critical habitat was designated for the western snowy plover December 7, 1999, again on September 29, 2005, and most recently on June 6, 2012. The current Pacific coast breeding population extends from Damon Point, Washington, south to Bahia Magdalena, Baja California, Mexico [including both Pacific and Gulf of California coasts)]. The western snowy plover winters mainly in coastal areas from southern Washington to Central America.



Habitat degradation caused by human disturbance, urban development, introduced beachgrass (Ammophila spp.), and expanding predator populations have resulted in a decline in active nesting areas and in the size of the breeding and wintering populations.

Yellow-billed cuckoo (Coccyzus americanus) (OR, WA, ID, MT)

Information in this section from USACE (2018).


Listing History

The western yellow-billed cuckoo was listed as threatened October 3, 2014, while critical habitat was proposed August 15, 2014, but a final designation has not been made. The western DPS includes Arizona, California (Baja California, Baja California Sur, Chihuahua, western Durango, Sinaloa, and Sonora), western Colorado, Idaho, western Montana, western New Mexico, Nevada, Oregon, western Texas, Utah, Washington, western Wyoming, and southwest British Columbia.


Life History/Biological requirements

As summarized by Cornell University ( Yellow-billed cuckoos use wooded habitat with dense cover and water nearby, including woodlands with low, scrubby, vegetation, overgrown orchards, abandoned farmland, and dense thickets along streams and marshes. In the Midwest, look for cuckoos in shrublands of mixed willow and dogwood, and in dense stands of small trees such as American elm. In the Southwest, yellow-billed cuckoos are rare breeders in riparian woodlands of willows, cottonwoods and dense stands of mesquite to breed.


Yellow-billed cuckoo prey largely on caterpillars. On the east coast, periodic outbreaks of tent caterpillars draw cuckoos to the tent-like webs, where they may eat as many as 100 caterpillars at a sitting. Fall webworms and the larvae of gypsy, brown-tailed, and white-marked tussock moths are also part of the cuckoo’s lepidopteran diet, often supplemented with beetles, ants, and spiders. They also take advantage of the annual outbreaks of cicadas, katydids, and crickets, and will hop to the ground to chase frogs and lizards. In summer and fall, cuckoos forage on small wild fruits, including elderberries, blackberries and wild grapes. In winter, fruit and seeds become a larger part of the diet.


Pairs may visit prospective nest sites multiple times before building a nest together. Nest heights can range from 0.98 yds (0.9 m) to as much as 30 yds (27.5 m) off the ground, with the nest placed on a horizontal branch or in the fork of a tree or large shrub. In the West, nests are often placed in willows along streams and rivers, with nearby cottonwoods serving as foraging sites.


The male and female yellow-billed cuckoo build a loose stick nest together, using twigs collected from the ground or snapped from nearby trees and shrubs. The male sometimes continues bringing in nest materials after incubation has begun. Clutch size can range from 1-5 eggs with up to 2 clutches per year.


Distribution and Critical Habitat

Critical habitat is proposed, but not yet designated for yellow-billed cuckoo. Critical habitat was proposed in 2013The breeding range of the yellow-billed cuckoo formerly included most of North America from southern Canada to the Greater Antilles and northern Mexico (AOU 1957, 1998).


In recent years, the species’ distribution in the west has contracted. The northern limit of breeding in the western coastal States is now in Sacramento Valley, California, and the northern limit of breeding in the western interior States is southern Idaho [AOU 1998; Hughes 1999. The species overwinters from Columbia and Venezuela, south to northern Argentina (Ehrlich et al. 1992; AOU 1998).


The greatest threat to the species has been reported to be loss of riparian habitat. It has been estimated that 90% of the cuckoo's stream-side habitat has been lost (USFWS 2018a). Habitat loss in the west is attributed to agriculture, dams, and river flow management, overgrazing and competition from exotic plants such as tamarisk.




Oregon spotted frog (Rana pretiosa) (OR, WA)

Information in this section from USACE (2018) and other sources.


Listing History

The Oregon spotted frog was listed as threatened August 29, 2014.


Life History/Biological requirements

Adult Oregon spotted frogs begin to breed by 1 to 3 years of age, depending on sex, elevation, and latitude. Males may breed at 1 year at lower elevations and latitudes, but generally breed at 2 years of age. Females breed by 2 or 3 years of age, depending on elevation and latitude. Breeding occurs in February or March at lower elevations and between early April and early June at higher elevations. Males and females separate soon after egg-laying, with females returning to fairly solitary lives. Males often stay at the breeding site, possibly for several weeks, until egg-laying is completed. Females may deposit their egg masses at the same locations in successive years.


The Oregon spotted frog life cycle requires shallow water areas for egg and tadpole survival; perennially deep, moderately vegetated pools for adult and juvenile survival in the dry season; and perennial water for protecting all age classes during cold wet weather. The Oregon spotted frog inhabits emergent wetland habitats in forested landscapes, although it is not typically found under forest canopy. Historically, this species was also associated with lakes in the prairie landscape of the Puget lowlands. This is the most aquatic native frog species in the Pacific Northwest, as all other species have a terrestrial life stage. Post-metamorphic Oregon spotted frogs are opportunistic predators that prey on live animals, primarily insects, found in or near the water.


Distribution and Critical Habitat

Critical habitat was designated for the Oregon spotted frog May 11, 2016. Historically, the Oregon spotted frog ranged from British Columbia to the Pit River basin in northeastern California. Currently, the Oregon spotted frog is found from extreme southwestern British Columbia south through the Puget Trough and in the Cascades Range from south-central Washington at least to the Klamath Basin in southern Oregon. Oregon spotted frogs occur in lower elevations in British Columbia and Washington and are restricted to high elevations in Oregon.


Oregon Spotted Frogs are highly aquatic and live in or near permanent bodies of water, including lakes, ponds, slow streams and marshes. They prefer areas with thick algae and vegetation for cover, but may also hide under decaying vegetation. They are most often found in non-woody wetland plant communities (species such as sedges, rushes and grasses). Most Oregon Spotted Frogs hibernate and aestivate. Oregon Spotted Frogs distribute through a wide range of altitudes and in Washington have been found from 40 to 620 meters above sea level (McAllister and Leonard 1997). Adults eat insects, mollusks, crustaceans and arachnids. Larvae eat algae and organic debris. The timing of breeding is related to ice melt on lakes, ponds and marshes. Breeding occurs from February to March in the lower elevations, and from March to April in the higher elevations in the Cascade Range. Oregon Spotted Frogs lay their eggs in the shallows of a permanent water source.


Oregon Spotted Frogs are generally associated with wetland complexes > 4 ha (10 acres) in size with extensive emergent marsh coverage that warms substantially from spring to fall (Pearl and Hayes 2004). Hayes (1994a, b) stressed the reliance of this species on warm-water habitats. Washington’s remaining populations of Oregon Spotted Frogs occupy palustrine wetlands connected to riverine systems. The perennial creeks and associated network of intermittent tributaries provide aquatic connectivity between breeding sites, active season habitat and overwintering habitat. Additionally, perennially flowing waters may provide the only suitable habitat during extreme summer drought or during winter when still-waters become hypoxic (low dissolved oxygen levels that are detrimental to aerobic organisms). Associated wetlands have a mix of dominance types including aquatic bed, emergent, scrub-shrub, and forested wetlands. The seasonally inundated wetland margins are frequently hay fields

and pasture. The less disturbed sites have wet meadows and prairie uplands. Some occupied sites are engineered by American Beaver (Castor canadensis, hereafter “beaver”). All the remaining Oregon Spotted Frog sites have moderate to severe habitat alteration including a history of cattle grazing and/or hay production as well as encroaching or established rural residential development. Hydrology has been altered to some extent at all sites with the most extensive changes at Conboy Lake National Wildlife Refuge and surrounding area.


Watson et al. (2000; Black River) found that different life stages of Oregon Spotted Frogs had different hydrological needs that varied by season. For development of eggs and larvae, relatively stable water levels were needed during the breeding season. For survival of transformed frogs, deeper water pools were critical during the summer dry season. Adequate water levels over emergent vegetation were important for survival of all age classes during the wet season and coldest time of the year. In general, frogs selected sedge-dominated and hardhack (Spiraea douglasii)–dominated types and avoided reed canarygrass types, alder/willow, and deep water. Uplands were not used. During the breeding season, frogs preferred sedge-dominated habitat particularly sedge/rush found in association with breeding sites. During the dry season, frogs preferred hardhack-dominated habitats. The hardhack was in the deepest waters and these retained water during dry periods. Also, the hardhack shaded out reed canarygrass preventing dense, impenetrable grass cover. Aquatic connectivity was essential; frogs did not move terrestrially to isolated ponds. The predominant use of shallow water habitat by Oregon Spotted Frogs was illustrated by Watson et al. (1998, 2003), who found Oregon Spotted Frogs (n = 295 radio-telemetry locations) selected water depths of 10–30 cm (~4–11.7 in.) with less emergent vegetation and more submergent vegetation than adjacent habitats.



Habitat alteration appears to be the primary threat to the Oregon spotted frog. Breeding locations makes Oregon spotted frogs acutely vulnerable to fluctuating water levels, disease, predation, poor water quality, and extirpation from stochastic events. Hydrologic changes, resulting from activities such as water diversions and removal of beavers, increase the likelihood of fluctuating water levels and temperatures, and may also facilitate predators.




Bull trout (Salvelinus confluentus) (OR, WA, ID, MT)

Information in this section from USACE (2018) and other sources.


Listing History

The USFWS issued a final rule listing the Columbia River population of bull trout as threatened on June 10, 1998, while critical habitat for this species was listed on October 18, 2010. Bull trout are currently listed throughout their range in the United States as a threatened species.


Life History/Biological requirements

Bull trout have four documented life history forms:

  • The stream-resident form lives out its life in small headwater streams;

  • The fluvial form lives as an adult in large rivers but spawns in small tributary streams (it often attains a large size, reaches sexual maturity at about five, and undergoes long migrations between mainstem rivers and small tributary spawning streams);

  • The lacustrine-adfluvial form spawns in tributary streams but lives as an adult in lakes (McPhail and Baxter 1996), often making long migrations between lakes and spawning streams; and

  • One anadromous form of bull trout exists in the Coastal Puget-Sound population—it spawns in rivers and streams, but rears young in the ocean. The species is known to occur in numerous counties throughout the Columbia River Basin states.


Habitat components that appear to influence bull trout distribution and abundance include water temperature, cover, channel form and stability, valley form, spawning and rearing substrates and migratory corridors (with resting habitat). All life history stages of bull trout are associated with complex forms of cover, including large woody debris, undercut banks, boulders and deep pools (Wydoski and Whitney 2003).


Distribution and Critical Habitat

Bull trout critical habitat was designated on October 18, 2010. In the Columbia River Basin, bull trout historically were found in about 60% of the basin. They now occur in less than half of their historic range. Populations remain in portions of Oregon, Washington, Idaho, Montana, and Nevada (Table 8).

Table 8. Acres and miles of Bull trout critical habitat in Idaho, Montana, Oregon and Washington.


Western snowy plover
Yellow-billed cuckoo
Oregon spotted frog
Bull trout

Bull trout have specific habitat requirements that influence their distribution and abundance. They are seldom found in waters where temperatures exceed 59 to 64 degrees Fahrenheit, and they require stable stream channels, clean spawning and rearing gravel, complex and diverse cover, and unblocked migratory corridors.


There are 118 bull trout core areas in Oregon, Washington, Idaho, Montana, and Nevada that are recognized by the US Fish and Wildlife Service (USFWS 2002b). Within the CRB, a total of 95 core areas are described (USFWS 2002b). They generally spawn from August to November during periods of decreasing water temperatures. Egg incubation is normally 100 to 145 days and fry remain in the substrate for several months.


To determine whether or not an action will affect bull trout critical habitat requires an analysis of how the action would affect the nine primary constituent elements (PCEs), or the habitat components essential for the primarily biological needs of foraging, reproducing, rearing of young, dispersal, genetic exchange, or sheltering.


1. Springs, seeps, groundwater sources, and subsurface water connectivity (hyporheic flows) to contribute to water quality and quantity and provide thermal refugia.


2. Migration habitats with minimal physical, biological, or water quality impediments between spawning, rearing, overwintering, and freshwater and marine foraging habitats, including but not limited to permanent, partial, intermittent, or seasonal barriers.


3. An abundant food base, including terrestrial organisms of riparian origin, aquatic macroinvertebrates, and forage fish. Bull trout shift their diet as they grow, feeding on aquatic insects when young (benthic invertebrates and plankton (Carl et al. 1989), and feeding on fish as they grow. Diet is primarily a reflection of food availability, e.g., in water bodies in which bull trout are the only fish species, bull trout forage on benthic invertebrates and plankton (Carl et al. 1989). When other fish species are present, bull trout begin to forage on fish when the bull trout are between 100 and 200 mm (Stewart et al. 1982; Boag 1987; Pratt 1992).


4. Complex river, stream, lake, reservoir, and marine shoreline aquatic environments, and processes that establish and maintain these aquatic environments, with features such as large wood, side channels, pools, undercut banks and unembedded substrates, to provide a variety of depths, gradients, velocities, and structure.


5. Water temperatures ranging from 2 to 15 °C (36 to 59 °F), with adequate thermal refugia available for temperatures that exceed the upper end of this range. Specific temperatures within this range will depend on bull trout life-history stage and form; geography; elevation; diurnal and seasonal variation; shading, such as that provided by riparian habitat; streamflow; and local groundwater influence.


6. In spawning and rearing areas, substrate of sufficient amount, size, and composition to ensure success of egg and embryo overwinter survival, fry emergence, and young-of-the-year and juvenile survival. A minimal amount of fine sediment, generally ranging in size from silt to coarse sand, embedded in larger substrates, is characteristic of these conditions. The size and amounts of fine sediment suitable to bull trout will likely vary from system to system.


7. A natural hydrograph, including peak, high, low, and base flows within historic and seasonal ranges or, if flows are controlled, minimal flow departure from a natural hydrograph.


8. Sufficient water quality and quantity such that normal reproduction, growth, and survival are not inhibited.


9. Sufficiently low levels of occurrence of non-native predatory (e.g., lake trout, walleye, northern pike, smallmouth bass); interbreeding (e.g., brook trout); or competing (e.g., brown trout) species that, if present, are adequately temporally and spatially isolated from bull trout.


Critical habitat includes the stream channels within the designated stream reaches, the shoreline of designated lakes, and the inshore extent of marine near shore areas, including tidally influenced freshwater heads of estuaries (USFWS 2014). In freshwater areas, critical habitat includes the stream channels within the designated stream reaches and a lateral extent as defined by the bankfull elevation on one bank to the bankfull elevation on the opposite bank (USFWS 2014). If bankfull elevation is not evident on either bank, the ordinary high-water line determines the lateral extent of critical habitat (USFWS 2014).


Associated flood plains, shorelines, riparian zones and upland habitat are important to critical habitat areas and that activities in these areas may affect bull trout critical habitat (USFWS 2014).


Adfluvial populations (fish that spawn in tributary streams and rear in streams for several years before migrating to lakes to grow to maturity) are found in large, oligotrophic, high altitude lakes. These populations spawn either in stream tributaries, or in the lake’s inlet or outlet (Carl et al. 1989). In large oligotrophic lakes, bull trout use all parts of the lake, foraging in the littoral zone in the fall and spring, and moving to deep water in summer (Goetz 1989). Bull trout move below the thermocline in lakes when the temperature of the littoral zone exceeds 15 degrees Celsius (Bjornn 1961). Even in the spring, bull trout are more abundance in deep water than near the surface (Chisholm et al. 1989). Emigration from spawning streams to lakes occurs throughout the summer (Chisholm et al. 1989).

The critical habitat designations applies only to stream channels defined by ordinary high-water line, or bank-full elevation. This designation does not extend to the floodplain or adjacent land.

To be included as critical habitat, an area had to currently be occupied (as documented within the last 20 years) and provide one or more of the following functions: (1) spawning, rearing, foraging, or over-wintering habitat to support essential existing bull trout local populations; (2) movement corridors necessary for maintaining essential migratory life-history forms; and/or (3) suitable habitat that is considered essential for recovering existing local populations that have declined or that need to be re-established to achieve recovery. Identification of these areas was based on the existence of primary constituent elements.

Primary constituent elements are physical and biological features that are essential to the conservation of the species. These include, but are not limited to: space for individual and population growth and for normal behavior; food, water, or other nutritional or physiological requirements; cover or shelter; sites for breeding, reproduction, or rearing of offspring; and habitats that are protected from disturbance or are representative of the historic geographical and ecological distributions of a species. All the areas proposed as critical habitat for bull trout are within the historic geographic range of the species and contain enough of these physical or biological features (primary constituent elements) essential to the conservation of the species for the species to be able to carry out normal biological function.



Table 9. Stream/shoreline distance (miles/kilometers) designated as bull trout critical habitat by critical habitat unit.

Kootenai River white sturgeon (Acipenser transmontanus) (ID, MT)

Information in this section from USFWS (1999) and USACE (2018).


Listing History

The Kootenai River population of white sturgeon was listed as endangered on September 6, 1994.


Life History/Biological requirements

The Kootenai River White Sturgeon is a land-locked species found along 167.7 miles of the Kootenai River extending from Kootenai Falls, Montana, located 31 river miles below Libby Dam, Montana, downstream through Kootenay Lake to Corra Linn Dam at the outflow from Kootenay Lake in British Columbia. The Kootenai River population of white sturgeon became isolated from other white sturgeon in the Columbia River basin during the last glacial age (approximately 10,000 years ago). Once isolated, the population adapted to the predevelopment habitat conditions in the Kootenai River drainage.


The species has been declining since the mid-1960, and its population has experienced almost no reproduction since 1974 because of habitat fragmentation—construction of the Libby Dam in Montana altered river flow patterns and reduced river productivity, human development (which has contributed to loss of ecological functions), dikes constructed along the river channel (which reduced riparian function and floodplain interaction), and pollution.


Historically, spring runoff events re-sorted river sediments providing a clean cobble substrate conducive to insect production and sturgeon egg incubation. Side channels and low-lying deltaic marsh lands were un-diked at this time, providing productive, low velocity backwater areas. Nutrient delivery in the system was unimpeded by dams and occurred primarily during spring runoff. Floodplain ecosystems like the predevelopment Kootenai River are characterized by seasonal floods that promote the exchange of nutrients and organisms in a mosaic of habitats and thus enhance biological productivity.


Distribution and Critical Habitat

Critical habitat was initially designated for white sturgeon September 6, 2001, with a revised designation July 9, 2008. The Kootenai River population is one of several land-locked populations of white sturgeon found in the Pacific Northwest. Although officially termed and listed as the “Kootenai River population of white sturgeon”, this white sturgeon population inhabits and migrates freely in the Kootenai River from Kootenai Falls in Montana downstream into Kootenay Lake, British Columbia, Canada. A total of 18 miles of the Kootenai River in Idaho is designated critical habitat. Specific actions needed for recovery include spring flow augmentation during the reproduction period; a conservation aquaculture program to prevent near-term extinction; habitat restoration, and research and monitoring programs to evaluate recovery progress (Duke et al. 1999).


Modification of the Kootenai River white sturgeon’s habitat by human activities has changed the natural hydrograph of the Kootenai River, altering white sturgeon spawning, egg incubation, and rearing habitats; and reducing overall biological productivity. These factors have contributed to a general lack of recruitment in the white sturgeon population since the mid-1960’s.


Spawning and rearing habitat are the key limiting factors for Kootenai River White Sturgeon. Spawning and incubation occur from mid-May to August (Duke et al. 1999). Depths for spawning white surgeon in the Lower Columbia River range from 3.5 to 25m—habitat suitability is poor for depths less than 2m, and moderate for depths of 2 to 4m (Parsley and Beckman 1994). Higher velocities are associated with more suitable substrate for white sturgeon egg incubation, greater egg dispersal, and reduction of egg predation (Barton et al. 2006). The greatest occurrence of white sturgeon spawning occurs in the area downstream of the mouth of Deep Creek at river kilometer mile 237.5 and 228.4 (Barton et al. 2006). Generally, habitat suitability is better in the straight reaches compared to meandering reaches because of coarser substrates and higher velocities (Barton et al. 2006). White sturgeon seldom spawn in the straight reach.


Lahontan cutthroat trout (Oncorhynchus clarki henshawi) (OR)

Information in this section from USFWS (1995) and USACE (2018).


Listing History

The Lahontan cutthroat (LCT) was listed as endangered October 13, 1970 and downlisted to threatened status on July 16, 1975 to facilitate management and allow regulated angling.


Life History/Biological requirements

Historically, LCT were found in a wide variety of cold-water habitats: Large terminal alkaline lakes (e.g., Pyramid Lakes); oligotrophic alpine lakes (e.g., Lake Tahoe); slow meandering low-gradient rivers (e.g., Humboldt River); moderate gradient montane rivers (e.g., Carson, Truckee, Walker, and Marys Rivers); and small headwater tributary streams. Habitat preferences are similar to other salmonids. Lahontan cutthroat inhabit small streams characterized by cool water, pools in close proximity to cover and velocity breaks, well vegetated and stable stream banks, and relatively silt free, rocky substrate in riffle-run areas. Fluvial LCT generally prefer rocky areas, riffles, deep pools, and habitats near overhanging logs, shrubs, or banks.


Typical of cutthroat trout subspecies, Lahontans are an obligatory stream spawner. Spawning occurs from April through July, depending on stream flow, elevation, and water temperature. Females mature at 3 to 4 years of age, and males at 2 to 3 years of age. Consecutive year spawning by individuals is uncommon. Lake residents migrate up tributaries to spawn in riffles or tail ends of pools. Distance traveled varies with stream size and race of cutthroat trout. Populations in Pyramid and Winnemucca Lakes reportedly migrated over 100 mi (160.9 km) up the Truckee River into Lake Tahoe. Lahontan cutthroat trout spawning migrations have been observed in water temperature ranging from 41–60.8 °F (5–16 °C).


Stream resident LCT are opportunistic feeders, with diets consisting of drift organisms, typically terrestrial and aquatic insects. In lakes, small LCT feed largely on insects and zooplankton, and larger LCT feed on fish.


Distribution and Critical Habitat

No critical habitat has been designated for Lahontan cutthroat trout. The Lahontan cutthroat is an inland subspecies of cutthroat trout endemic to the physiographic Lahontan basin of northern Nevada, eastern California, and the Coyote Lake basin in southeast Oregon. Lahontan cutthroat trout currently occupy between 155 and 160 streams; 123 to 129 streams within the Lahontan basin and 32 to 34 streams outside the basin, with approximately 482 mi (775.7 km) of occupied habitat.


Major impacts to LCT habitat and abundance include: 1) reduction and alteration of stream discharge; 2) alteration of stream channels and morphology; 3) degradation of water quality; 4) reduction of lake levels and concentrated chemical components in natural lakes; and 5) introductions of non-native fish species. These alterations are typically associated with agricultural use, livestock and feral horse grazing, mining, and urban development. Alteration and degradation of LCT habitat have also resulted from logging, highway and road construction, dam building, and the discharge of effluent from wastewater treatment facilities.


Lahontan cutthroat trout are native to the following southeastern Oregon streams: Willow Creek, Whitehorse Creek, Little Whitehorse Creek, Doolitle Creek, Fifteen Mile Creek in the Coyote Lake Basin; and Indian Creek, Sage Creek, and Line Canyon Creek, tributaries of McDermitt Creek in the Quinn River basin (which flows into Nevada).

Lahontan cutthroat trout are obligate but opportunistic stream spawners. Typically, they spawn from April through July, depending on water temperature and flow characteristics. Autumn spawning runs have been reported from some populations. The fish may reproduce more than once, though post-spawning mortality is high (60 to 90 percent). Lake residents migrate into streams to spawn, typically in riffles on well washed gravels. The behavior of this subspecies is typical of stream spawning trout; adults court, pair, and deposit and fertilize eggs in a redd dug by the female. Although the Lahontan cutthroat in Oregon were originally classified as Willow-Whitehorse cutthroat trout, genetic and taxonomic investigations led to the re-classification in 1991 (Williams 1991).


Lahontan trout are stocked in Mann Lake, the only place in Oregon stocked with this desert race of cutthroat trout.[5]


The Quinn River Lahontan Cutthroat Trout SMU is comprised of four populations, three of which are now extinct due to hybridization with non-native rainbow trout. Sage Creek is the only population to persist in the SMU, has an extremely limited distribution and abundance, and is vulnerable to hybridization. Distribution of Lahontan cutthroat trout in the Oregon portion of the Quinn River Basin is limited to 15 km in Sage and Line Canyon creeks.


The Coyote Lake SMU is comprised of five native cutthroat trout populations. Distribution is naturally fragmented, restricted by barrier falls and a discontinuous stream network. Three populations have low abundance and limited productivity. Lahontan cutthroat trout are the only fish species present in Willow, Whitehorse, and Antelope basins.

Kootenai River white sturgeon
Lahontan cutthroat trout


Banbury Springs limpet (Lanx spp.) (ID) 

Currently this species only exists at four cold-spring locations along the Snake River in Idaho that are isolated from each other: Thousand Springs, Box Canyon Springs, Briggs Springs and Banbury Springs. Primary factors affecting the lanx in its four remaining coldwater spring complexes and tributaries are habitat modification, spring flow reduction, groundwater quality, the invasive New Zealand mudsnail and inadequate regulatory mechanisms.

Bliss Rapids snail (Taylorconcha serpenticola) (ID)

ECOS—The Bliss Rapids snail occurs in cold water springs and spring-fed tributaries to the Snake River, and in some reaches of the Snake River. The Bliss Rapids snail is primarily found on cobble boulder substrate, and in water temperatures between 59–61 degrees Fahrenheit. Recent surveys indicate the species is distributed discontinuously over 22 miles, from River Mile (RM) 547-560, RM 566-572, and at RM 580 on the Snake River. The species is also known to occur in 14 springs or tributaries to the Snake River. The species does not occur in reservoirs.

It lives on stable rocks in flowing waters in the free-flowing reaches of the Snake River and in several cold-water springs in the Hagerman Valley (Bogan 2000). During the daytime, the snail resides on the sides and undersides of rocks.


Historically, this species occurred from Indian Cove Bridge to Twin Falls (Hershler et al. 1994). Populations occur in the lower reaches of the Malad River and in the Snake River between the springs above Hagerman and King Hill.


Snake River physa snail (Physa natricina) (ID)

The Snake River physa snail is a freshwater mollusk found in the middle Snake River of southern Idaho. It has an ovoid shell that is amber to brown in color, and has 3 to 3.5 whorls (curls or turns in the shell). The physa can reach a maximum length of about 6.5 millimeters. The Snake River physa is believed to have evolved in the Pliocene to Pleistocene lakes and rivers of northern Utah and southeastern Idaho. While much information exists on the family Physidae, very little is known about the biology or ecology of this species. It is believed to be confined to the Snake River, inhabiting areas of swift current on sand to boulder-sized substrate. In 1995, the Service reported the known modern range of the species to be from Grandview, Idaho (RM 487) to the Hagerman Reach of the Snake River (RM 573). More recent investigations have shown this species to occur outside of this historic range to as far downstream as Ontario, Oregon (RM 368), with another population known to occur downstream of Minidoka Dam (RM 675). While the species’ current range is estimated to be over 300 river miles, the snail has been recorded in only 5% of over 1,000 samples collected within this area, and it has never been found in high densities. The species’ status is uncertain within the current known range, but portions of the middle Snake River (e.g., Milner Reservoir, RM 663 to Lower Salmon Falls Reservoir, RM 572) are of questionable habitat value given current water quality and water use issues. In addition, the sampling in this reach has been limited. Very few live specimens have been recovered from reservoirs which have been extensively sampled. The recovery area for the species extends from Snake River mile 553 to Snake River mile 675. It is currently listed as an Endangered species.


The species historical range included Idaho.





Bradshaw’s desert parsley (Lomatium bradshawii) (OR, WA)  

The majority of Bradshaw's lomatium populations occur on seasonally saturated or flooded prairies, adjacent to creeks and small rivers in the southern Willamette Valley. Soils at these sites are dense, heavy clays, with a slowly permeable clay layer located 15-30 cm (6-12 in) below the surface. This clay layer results in a perched water table during winter and spring, and is critical to the wetland character of these grasslands, known as tufted hair-grass (Deschampsia cespitosa) prairies. Bradshaw's lomatium occurs on alluvial (deposited by flowing water) soils. The species occurs on soils in the Wapto, Bashaw and Mcalpin Series (NRCS mapped soil unit STATSGO 81). Note: The distribution of this species should be reviewed prior to any actions along creeks and small rivers in the southern Willamette Valley to determine presence and the potential to affect this species as a result of any activities associated an action.


Nelson’s checker-mallow (Sidalcea nelsoniana) (OR, WA)

Within the Willamette Valley, Nelson's checkermallow most frequently occurs in Oregon ash (Fraxinus latifolia) swales and meadows with wet depressions, or along streams. The species also grows in wetlands within remnant prairie grasslands. Some populations occur along roadsides at stream crossings where non-native plants, such as reed canarygrass (Phalaris arundinacea), blackberry (Rubus spp.), and Queen Anne's lace (Daucus carota), are also present. Nelson's checkermallow primarily occurs in open areas with little or no shade and will not tolerate encroachment of woody species. Note: The distribution of this species should be reviewed prior to any actions streams in its distribution in Oregon and Washington to determine presence and the potential to affect this species as a result of any activities associated an action.


Ute Ladies’-tresses (Spiranthes diluvialis) (WA, ID, MT)

Information in this section from the USFWS ECOS database and USACE (2018).


Listing History

Ute ladies’-tresses was listed as threatened on January 17, 1992. On October 12, 2004 there was a petition filed to delist Ute ladies’-tresses. The petition states that there is substantial new information indicating that the population size and distribution are much larger than known at the time of listing; there is more information on life history and habitat needs, allowing for better management, and threats are not as great in magnitude or imminence as understood at the time of listing. This plant remains listed as threatened.


Ute ladies’-tresses is a perennial herb with erect, glandular-pubescent stems 5-24 in (12.7 to 61 cm) tall arising from tuberous-thickened roots. It reproduces exclusively by seed. The plant’s life cycle consists of four main stages: seedling, dormant, vegetative, and reproductive. Fruits are produced in late August or September with seeds shed shortly thereafter. Seeds are microscopic, dust-like, and readily dispersed by wind or water. This plant may remain dormant for eight to eleven years and may revert to below ground existence for one to four or more growing seasons before re-emerging with new above-ground shoots.


The vegetative shoots are produced in October and persist through the winter as small rosettes. These resume growth in the spring and develop into short-stemmed, leafy plants. It blooms from early July to late October. Flowering typically occurs earlier in sites that have an open canopy and later in well-shaded sites. Bees are the primary pollinators of Ute ladies’-tresses, particularly solitary bees.


In perennial streamside populations, Ute ladies’-tresses typically occur on shallow sandy loam, silty-loam, or clayey-silt alluvial soils overlying more permeable cobbles, gravels, and sediments. It is dominated by perennial graminoids and forbs, particularly Agrostis stolonifea, Elymus repens, Juncus balticus, and Equisetum laeigatum. Ute ladies’-tresses populations may persist for a short time in the grassy understory of woody riparian shrublands, but do not appear to thrive under these conditions (Ward and Naumann 1998).


Distribution and Critical Habitat

No critical habitat has been designated for this species. Populations of Ute ladies’-tresses orchids are known from three broad general areas of the interior western United States—near the base of the eastern slope of the Rocky Mountains in southeastern Wyoming and adjacent Nebraska and north-central and central Colorado; in the upper Colorado River basin, particularly in the Uinta Basin; and in the Bonneville Basin along the Wasatch Front and westward in the eastern Great Basin, north-central and western Utah, extreme eastern Nevada, and southeastern Idaho. The species is also known to occur in Bonneville, Fremont, Jefferson, and Madison counties along the Snake River, has been discovered in southwestern Montana, and in the Okanogan area and along the Columbia River in North Central Washington.


The orchid occurs along riparian edges, gravel bars, old oxbows, high flow channels, and moist to wet meadows along perennial streams. It typically occurs in stable wetland and seepy areas associated with old landscape features within historical floodplains of major rivers. It also is found in wetland and seepy areas near freshwater lakes or springs. Note: The distribution of this species should be reviewed prior to any actions along riparian areas, rivers, and streams in its known distribution to determine potential to affect this species as a result of any activities associated an action.



Water howellia (Howellia aquatilis) (OR, WA, ID, MT)

Information in this section from USFWS ECOS database and USACE (2018).


Listing History

Water howellia was listed as threatened on July 14, 1994.


Life History/Biological requirements

Water howellia is an annual aquatic species in the bellflower family (Campanulaceae). Individuals are mostly submerged and rooted in bottom sediments. Stems branch near the soil surface and are 1.5-2.8 in (4-7 cm) long. The leaves are numerous and linear to linear-filiform, measuring 0.4-0.6 in (1-5 cm) long, with an entire margin or with a few teeth. The flowers are axillary, 0.08-0.11 in (2-2.7 mm) long, and a corolla is present (in emergent flowers) or lacking (in underwater flowers). The corolla is white to pale lavender and is deeply cleft on one side. The fruit is 0.3-0.4 in (8-10 mm) long. The seeds number 1-5 and are 0.08-0.2 in (2-4 mm) long. This species typically blooms May through August.


Information on herbarium labels or Oregon collections describe the habitat as "ponds in woods", "pond in shaded woods", and "stagnant ponds in the timber". Information from other locales indicate that this species is restricted to small, vernal, freshwater wetlands, glacial pothole ponds, or former river oxbows that have an annual cycle of filling with water over the fall, winter and early spring, followed by drying during the summer months. These habitats are generally small [< 2.47 ac (1 ha)] and shallow [< 3.3 ft (1 m deep)]. Bottom surfaces are reported as firm, consolidated clay, and organic sediments. Most locations were surrounded by deciduous trees and howellia was found in shallow water or around the edges of deep ponds. Associated species include duckweed (Lemna spp.), water starworts (Callitriche spp.), water buttercup (Ranunculus aquaticus), yellow water-lily (Nuphar polysepalum), bladderwort (Utricularia vulgaris), and pondweeds (Potamogeton spp.)


Distribution and Critical Habitat

No critical habitat has been designated for this species. Historically, water howellia was known to occur in one location in Mendocino County, California, four locations in northwest Oregon, two additional locations in Washington, and one location in northern Idaho.


As of drafting the recovery plan for this species in 1995, water howellia was known to occur in six locations; one in Idaho, three in Washington, and one in Montana, and one in California.



Habitat destruction appears to be the main threat and cause for decline of water howellia. Road and pasture development, grazing and trampling, timber harvest, invasive species, and wetland succession have been documented as potential factors.


Willamette daisy (Erigeron decumbens var. decumbens) (OR)

This species occurs on alluvial soils (deposited by flowing waters). The Willamette daisy occurs on soils in the Wapto, Bashaw and Mcalpin Series (NRCS mapped soil unit STATSGO 81). The species is known to have been extirpated (destroyed or no longer surviving) from an additional 19 historic locations. Willamette daisy populations are known mainly from bottomland, but one population is found in an upland prairie remnant. Currently, 18 sites are known, distributed over an area of 700,000 hectares (1.7 million acres), between Grand Ronde and Goshen, Oregon. Note: The distribution of this species should be reviewed prior to any actions along riparian areas, rivers, and streams in its known distribution to determine potential to affect this species as a result of any activities associated an action.

Banbury Springs limpet
Bliss Rapids snail
Snake River physa snail
Bradshaw's desert parsley
Nelson's checker-mallow
Ute ladies'-tresses
Water howellia
Willamette daisy
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