3. Land use designations and current or planned activities in areas occupied by the species, and their possible impacts on the species and the proposed critical habitat.

4. Any foreseeable economic, national security, or other potential impacts resulting from the proposed designation and, in particular, any impacts on small entities and the benefits of including or excluding areas that exhibit these impacts.

5. Whether the benefits of excluding any particular area from critical habitat outweigh the benefits of including that area as critical habitat under section 4(b)(2) of the Act, after considering the potential impacts and benefits of the proposed critical habitat designation.

6. Special management considerations or protections that the proposed critical habitat may require.

7. Whether we could improve or modify our approach to designating critical habitat in any way to provide for greater public participation and understanding, or to better accommodate concerns and comments.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in the ADDRESSES section. We will not consider comments sent by email or fax or to an address not listed in the ADDRESSES section.

If you submit a comment via http://www.regulations.gov, your entire commentincluding any personal identifying informationwill be posted on the Web site. If you submit a hardcopy comment that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy comments on http://www.regulations.gov.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection at http://www.regulations.gov, or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Oregon Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).

You may obtain copies of the proposed rule by mail from the Oregon Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT) or by visiting the Federal eRulemaking Portal at http://www.regulations.gov. Background

It is our intent to discuss only those topics directly relevant to the designation of critical habitat in this proposed rule. For a more complete discussion of the ecology and life history of this species, please see the Oregon Chub 5year Review Summary and Evaluation completed February 11, 2008 (http://www.fws.gov/pacific/ecoservices/ endangered/recovery/Documents/Oregonchub.pdf ).

Description and Taxonomy

The Oregon chub (Oregonichthys crameri) was first described in scientific literature in 1908 (Snyder 1908, pp. 181182), but it wasn't until 1991 that it was identified as a unique species (Markle et al. 1991, pp. 284289). Oregon chub have an olivecolored back (dorsum) grading to silver on the sides and white on the belly. Scales are relatively large with fewer than 40 occurring along the lateral line; scales near the back are outlined with dark pigment (Markle et al. 1991, pp. 286288). While young of the year range in length from 7 to 32 millimeters (mm) (0.3 to 1.3 inches (in)), adults can be up to 90 mm (3.5 in) in length (Pearsons 1989, p. 17). The species is distinguished from its closest relative, the Umpqua chub (Oregonichthys kalawatseti), by Oregon chub's longer caudal peduncle (the narrow part of a fish's body to which the tail is attached), mostly scaled breast, and more terminal mouth position (Markle et al. 1991, p. 290).
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Distribution and Habitat

Oregon chub are found in slackwater, offchannel habitats with little or no flow, silty and organic substrate, and considerable aquatic vegetative cover for hiding and spawning (Pearsons 1989, p. 10; Markle et al. 1991, p. 288; Scheerer and Jones 1997, p. 5; Scheerer et al. 2007, p. 3). The species' aquatic habitat is typically at depths of less than or equal to 2 meters (m) (6.6 feet (ft)), and has a summer subsurface water temperature exceeding 15 [deg]Celsius ([deg]C) (61 [deg]Fahrenheit ([deg]F)) (Scheerer and Apke 1997, p. 45; Scheerer 2002, p. 1073; Scheerer and McDonald 2003, p. 69). Optimal Oregon chub habitat provides 1 square meter (m\2\) (11 square feet (ft\2\)) of aquatic surface area per adult, at depths between 0.5 m (1.6 ft) to 2 m (6.6 ft) (Scheerer 2008b). Oregon chub can be relatively long lived with males living up to 7 years and females up to 9 years, although less than 10 percent of fish in most Oregon chub populations are older than 3 years (Scheerer and McDonald 2003, p. 71). Outside of spawning season, the species is social and nonaggressive with fish of similar size classes schooling and feeding together (Pearsons 1989, pp. 1617).

The species is endemic to the Willamette River drainage of western Oregon (Markle et al. 1991, p. 288) and was formerly distributed throughout the Willamette River Valley in a dynamic network of off channel habitats such as beaver ponds, oxbows, side channels, backwater sloughs, lowgradient tributaries, and flooded marshes in the floodplain (Snyder 1908, p. 182). Records show Oregon chub were found as far downstream as Oregon City, as far upstream as Oakridge, and in various tributaries within the Willamette basin (Markle et al. 1991, p. 288).

Historically, Oregon chub would be dispersed and their habitat regularly altered, increased, or eliminated due to regular winter and spring flood events (Benner and Sedell 1997, pp. 2728); this dispersal created opportunities for interbreeding between different populations. The installation of the flood control projects in the Willamette River basin altered the natural flow regime, and flooding no longer plays a positive role in creating Oregon chub habitat or providing opportunities for genetic mixing of populations. Flood events now threaten Oregon chub populations due to the dispersal of nonnative species that compete with or prey on Oregon chub. Whereas natural perturbations like floods often favor native species over nonnative species, human perturbations typically favor the nonnative species. In the Santiam River basin, the two largest natural populations of Oregon chub declined substantially after nonnative fishes invaded these habitat during the 1996 floods, and no new populations of Oregon chub were discovered in habitats located downstream of existing chub populations during thorough sampling in 19972000. This suggests that no successful colonization occurred as a result of the flooding event (Scheerer 2002, p. 1078).

Currently, the largest populations of Oregon chub occur in locations with the highest diversity of native fish, amphibian, reptile and plant species (Scheerer and Apke 1998, p. 11). Beaver (Castor canadensis) appear to be especially important in creating and maintaining habitats that support these diverse native species assemblages (Scheerer and Apke 1998, p. 45). Conversely, the establishment and expansion of nonnative species in Oregon have contributed to the decline of the Oregon chub, limiting the species' ability to expand beyond its current range (Scheerer 2007, p. 92). Many sites formerly inhabited by the Oregon chub are now occupied by nonnative species (Scheerer et al. 2007, p. 9; Scheerer 2007a, p. 96). Sites with high connectivity to adjacent flowing water frequently contain nonnative predatory fishes and rarely contain Oregon chub (Scheerer 2007, p. 99). The presence of centrarchids (e.g., Micropterus sp. (largemouth bass, smallmouth bass, bluegill) and Pomoxis sp. (crappies)), and bullhead catfishes (Ameiurus sp.) is probably preventing Oregon chub from recolonizing suitable habitats throughout the basin (Markle et al. 1991, p. 291).

Although surveys conducted by the Oregon Department of Fish and Wildlife (ODFW) prior to the 1993 listing of Oregon chub as endangered under the Act indicated the presence of the species at 17 different locations, the impacts of floodplain alteration and nonnative predators and competitors were clearly represented in the relatively small numbers of Oregon chub found at these sites. At the time of listing, these surveys were the best evidence of the thencurrent distribution of the species. Of these 17 sites, only 9 supported populations of 10 or more Oregon chub, and all but 1 of those populations were found within a 30kilometer (km) (19mile (mi)) stretch of the Middle Fork Willamette River in the vicinity of Dexter and Lookout Point Reservoirs in Lane County, Oregon; this stretch represented just 2 percent of the species' historical range (58 FR 53800; October 18, 1993). Very small numbers of the species, between 1 and 7 individuals, were found at the remaining eight of the 17 sites at the time of listing. Currently, the distribution of Oregon chub is limited to 25 known naturally occurring populations and 11 reintroduced populations scattered throughout the Willamette Valley (Scheerer et al. 2007, p. 2; 2008a, p. 2). Previous Federal Actions
In 1993, we listed Oregon chub as endangered, in accordance with the Endangered Species Act (Act) (58 FR 53800; October 18, 1993). In that listing, we concluded that critical habitat was prudent but not determinable. A recovery plan for the Oregon chub was completed in 1998 (USFWS 1998). The Oregon chub recovery plan established certain criteria for downlisting the species from endangered to threatened, which included establishing and managing 10 populations of at least 500 adults each that exhibit a stable or increasing trend for 5 years. The recovery plan states that, for purposes of downlisting the species, at least three populations must be located in each of the three subbasins of the Willamette River identified in the plan (Mainstem Willamette River, Middle Fork Willamette, and Santiam River). The recovery plan also established criteria for delisting the Oregon chub (i.e., removing it from the List of Endangered and Threatened Wildlife). These include establishing and managing 20 populations of at least 500 adults each, which demonstrate a stable or increasing trend for 7 years. In addition, at least four populations must be located in each of the three subbasins (Mainstem Willamette River, Middle Fork Willamette, and Santiam River). The management of these populations must be guaranteed in perpetuity.

On March 9, 2007, the Institute for Wildlife Protection filed suit in Federal district court, alleging that the Service and the Secretary of the Interior violated their statutory duties as mandated by the Act when they failed to designate critical habitat for the Oregon chub and failed to perform a 5year status review (Institute for Wildlife Protection v. U.S. Fish and Wildlife Service). On March 8, 2007, we issued a notice that we would begin a status review of the Oregon chub (72 FR 10547). We completed the Oregon chub 5Year Review on February 11, 2008. In a settlement agreement with the Plaintiff, we agreed to submit a proposed critical habitat rule for Oregon chub to the Federal Register by March 1, 2009, and to submit a final critical habitat determination to the Federal Register by March 1, 2010.

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We have established two Safe Harbor Agreements (SHAs) for the Oregon chub; both in Lane County, Oregon, in 2001 (66 FR 30745; June 7, 2001) and 2007 (72 FR 50976; September 5, 2007). These SHAs established new populations of Oregon chub in artificial ponds as refugia for natural populations, which contributes to the conservation of the species by reducing the risk of the complete loss of donor populations and any of their unique genetic material. The SHA policy was developed to encourage private and other nonFederal property owners to voluntarily undertake management activities on their property to enhance, restore, or maintain habitat to benefit federally listed species. SHAs provide assurances to property owners allowing alterations or modifications to enrolled property, even if such actions result in the incidental take of a listed species. For more information on previous Federal actions concerning the Oregon chub, refer to the Determination of Endangered Status for the Oregon Chub published in the Federal Register on October 18, 1993 (58 FR 53800) or the 1998 Recovery Plan for Oregon Chub (USFWS 1998).

Critical Habitat

Critical habitat is defined in section 3 of the Act as:

1. The specific areas within the geographical area occupied by a species, at the time it is listed in accordance with the Act, on which are found those physical or biological features

a. Essential to the conservation of the species, and

b. Which may require special management considerations or protection; and

2. Specific areas outside the geographical area occupied by a species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.

Conservation, as defined under section 3 of the Act, means the use of all methods and procedures that are necessary to bring any endangered species or threatened species to the point at which the measures provided under the Act are no longer necessary.

Critical habitat receives protection under section 7 of the Act through the prohibition against Federal agencies carrying out, funding, or authorizing activities that result in the destruction or adverse modification of critical habitat. Section 7 of the Act requires consultation on Federal actions that may affect critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow government or public access to private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by the landowner. Where the landowner seeks or requests Federal agency funding or authorization of an activity that may affect a listed species or critical habitat, the consultation requirements of section 7 would apply. However, even if a destruction or adverse modification finding were to be made, a landowner's obligation would not be to restore or recover the species, but rather, to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat in order to receive the federal agency funding or

authorization.

For inclusion in a critical habitat designation, habitat within the geographic area occupied by the species at the time it was listed must contain the physical and biological features that are essential to the conservation of the species. Critical habitat designations identify, to the extent known using the best scientific data available, habitat areas that provide essential life cycle needs of the species (areas on which are found the primary constituent elements, as defined at 50 CFR 424.12(b)). Occupied habitat that contains features essential to the conservation of the species meets the definition of critical habitat only if those features may require special management considerations or protection. Under the Act, we can designate areas that were unoccupied at the time of listing as critical habitat only when we determine that the best available scientific data demonstrate that the designation of that area is essential to the conservation of the species. When the best available scientific data do not demonstrate that the conservation needs of the species require such additional areas, we will not designate critical habitat in areas outside the geographical area occupied by the species at the time of listing. An area currently occupied by the species but that was not occupied at the time of listing may, however, be essential to the conservation of the species and may be included in the critical habitat designation.

Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific data available. Further, our Policy on Information Standards Under the Endangered Species Act, published in the Federal Register on July 1, 1994 (59 FR 34271), and Section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106554; H.R. 5658) and the associated Information Quality Guidelines issued by the Service, provide criteria, and establish procedures and guidelines to ensure that decisions made by the Service represent the best scientific data available. They require Service biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.

When we are determining which areas should be proposed as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peerreviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.

Habitat is often dynamic, and species may move from one area to another over time. Furthermore, we recognize that designation of critical habitat may not include all of the habitat areas that we may eventually determine are necessary for the recovery of the species, based on scientific data not now available to the Service. For these reasons, a critical habitat designation does not signal that habitat outside the designated area is unimportant or may not be required for recovery of the species.

Areas that support populations, but are outside the critical habitat designation, may continue to be subject to conservation actions we implement under section 7(a)(1) of the Act. They are also subject to the regulatory protections afforded by the Section 7(a)(2) jeopardy standard, as determined on the basis of the best scientific information at the time of the agency action. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance of future recovery plans, habitat conservation plans (HCPs), or other species conservation planning efforts if new information available to these planning efforts calls for a different outcome.

Methods

As required by section 4(b)(2) of the Act, we use the best scientific data
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available in determining areas that contain the features that are essential to the conservation of the Oregon chub. Data sources include research published in peerreviewed articles; previous Service documents on the species, including the final listing determination (58 FR 53800; October 18, 1993) and the Recovery Plan for the Oregon chub (USFWS 1998); and annual surveys conducted by the ODFW (1992 through 2008, as summarized in Scheerer et al. 2007 and Scheerer 2008a). Additionally we utilized regional Geographic Information System (GIS) shape files for area calculations and mapping.

Primary Constituent Elements

In accordance with section 3(5)(A)(i) of the Act and regulations at 50 CFR 424.12(b), in determining which areas occupied at the time of listing to propose as critical habitat, we consider the physical and biological features that are essential to the conservation of the species and that may require special management considerations or protection. These features are the primary constituent elements (PCEs) laid out in the appropriate quantity and spatial arrangement for conservation of the species. These include, but are not limited to:

1. Space for individual and population growth and for normal behavior;

2. Food, water, air, light, minerals, or other nutritional or physiological requirements;

3. Cover or shelter;

4. Sites for breeding, reproduction, and rearing (or development) of offspring; and

5. Habitats that are protected from disturbance or are representative of the historical geographical and ecological distributions of a species.

We derive the specific PCEs required for the Oregon chub from the biological needs of the species as described in the Background section of this proposed rule and the following information.
Space for Individual and Population Growth and Normal Behavior Flow Velocities and Depth

Oregon chub habitats are typically slackwater offchannel water bodies with little or no flow, such as beaver ponds, oxbows, side channels, backwater sloughs, lowgradient tributaries (less than 2.5 percent gradient) and flooded marshes (Pearsons 1989, p. 3031; Markle et al. 1991, pp. 288289; Scheerer et al. 2007, p. 3; Scheerer 2008e). The species' swimming ability has been described as poor, and it is believed that no or low flow velocity water optimizes the energy expenditure of these slow fish (Pearsons 1989, p. 3031). Although Oregon chub habitat may contain water of somewhat greater depth, the species mainly occupies water depths between approximately 0.52.0 m (1.66.6 ft). In order for a habitat to provide enough space to allow normal behavior for a population of 500 or more individuals, the water body needs to include approximately 500 square meters (m\2\ ) (0.12 ac) or more of aquatic surface area between 0.52.0 m (1.66.6 ft) deep. (Scheerer 2008b).

Cover

The species' habitat preference varies depending on lifestage and season, but all Oregon chub require considerable aquatic vegetation for hiding and spawning activities (Pearsons 1989, p. 22; Markle et al. 1991, p. 290; Scheerer and Jones 1997, p. 5; Scheerer et al. 2007, p. 3). A minimum of 250 m\2\ (0.06 ac) (or between approximately 25 and 100 percent of the total surface area of the habitat) to be covered with aquatic vegetation is needed to provide lifehistory requirements for a population of 500 Oregon chub (Scheerer 2008e). Aquatic plant communities within Oregon chub habitat include, but are not limited to, both native and nonnative species, including:

1. Emergent vegetation: Carex spp. (sedge); Eleocharis spp. (spikerush); Scirpus spp. (bulrush); Juncus spp. (rush); Alisma spp. (water plantain); Polygyonum spp. (knotweed); Ludwigia spp. (primrose willow); Salix spp. (willow); Sparganium spp. (burreed); and Typha spp. (cattail).

2. Partly submerged/emergent vegetation: Ranunculus spp. (buttercup).

3. Floating/submerged vegetation: Azolla spp. (mosquitofern); Callitriche sp. (waterstarwort); Ceratophyllum sp. (hornwort); Elodea spp. (water weed); Fontinalis spp. (fontinalis moss); Lemna spp. (duckweed); Myriophyllum spp. (parrot feather); Nuphar spp. (pond lily); and Potamogeton spp. (pondweed) (Scheerer 2008c).

Oregon chub in similar size classes school and feed together. Larval Oregon chub congregate in the upper layers of the water column, especially in shallow, nearshore areas. Juvenile Oregon chub venture farther from shore into deeper areas of the water column. Adult Oregon chub seek dense vegetation for cover and frequently travel in the mid water column in beaver channels or along the margins of aquatic plant beds. In the early spring, Oregon chub are most active in the warmer, shallow areas of the ponds (Pearsons 1989, pp. 1617; USFWS 1998, p. 10).

Substrates

Because Oregon chub habitat is characterized by little or no water flow, resulting substrates are typically composed of silty and organic material. In winter months, Oregon chub of various life stages can be found buried in the detritus or concealed in aquatic vegetation (Pearsons 1989, p. 16). Females prefer a highly organic, vegetative substrate for spawning and will lay their adhesive eggs directly on the submerged vegetation (Pearsons 1989, p. 17, 23; Markle et al. 1991. p. 290; Scheerer 2007b, p. 494).

Food

Known as obligatory sight feeders (Davis and Miller 1967, p. 32), Oregon chub feed throughout the day and stop feeding after dusk (Pearsons 1989, p. 23). The fish feed mostly on water column fauna, especially invertebrates that live in dense aquatic vegetation. Markle et al. (1991, p. 288) found that the diet of Oregon chub adults consisted primarily of minute crustaceans including copepods, cladocerans, and chironomid larvae. The diet of juveniles also consists of minute organisms such as rotifers, copepods, and cladocerans (Pearsons 1989, p. 4142).

Water Quality

With respect to water quality, the temperature regime at a site may determine the productivity of Oregon chub at that location. Spawning activity for the species has been observed from May through early August when subsurface water temperatures exceed 15 [deg]C (59 [deg]F) or 16 [deg]C (61 [deg]F) (Scheerer and Apke 1997, p. 22; Markle et al. 1991, p. 288; Scheerer and MacDonald 2003, p. 78). The species will display normal lifehistory behavior at temperatures between approximately 15 and 25 [deg]C (59 and 77 [deg]F). The upper lethal temperature for the fish was determined to be 31 [deg]C (88 [deg]F) in laboratory studies (Scheerer and Apke 1997, p. 22).

Optimal Oregon chub habitat contains water with dissolved oxygen levels greater than 3 parts per million (ppm), and an absence of contaminants such as copper, arsenic, mercury, and cadmium; human and animal waste products; pesticides; nitrogen and phosphorous fertilizers; and gasoline or diesel fuels. However, the species habitat is also characterized by high primary productivity and frequent algal blooms that might cause natural variability in water quality, especially dissolved oxygen levels (Scheerer and Apke 1997, [[Page 10416]]
p. 15). Optimal Oregon chub habitat includes water dominated by fine substrates, but protected from excessive sedimentation. When excessive sediment is deposited, surface area can be lost as the sediment begins to displace open water. The resulting succession of open water habitat to wet meadow is detrimental to Oregon chub populations (Scheerer 2008c).

The water quality in the habitats of many known extant Oregon chub populations is threatened due to their proximity to areas of human activity. Many of the known extant populations of Oregon chub occur near rail, highway, and power transmission corridors and within public park and campground facilities. These populations may be threatened by chemical spills from overturned truck or rail tankers; runoff or accidental spills of vegetation control chemicals; overflow from chemical toilets in campgrounds; sedimentation of shallow habitats from construction activities; and changes in water level or flow conditions from construction, diversions, or natural desiccation. Oregon chub populations near agricultural areas are subject to poor water quality as a result of runoff laden with sediment, pesticides, and nutrients. Logging in the watershed can result in increased sedimentation and herbicide runoff (USFWS 1998, p. 14).

Reproduction and Rearing of Offspring

Although most mature Oregon chub are found to be greater than or equal to 2 years old, maturity appears to be mainly size rather than agedependent (Scheerer and McDonald 2003, p. 78). Males over 35 mm (1.4 in) have been observed exhibiting spawning behavior. Oregon chub spawn from April through September, when temperatures exceed 15 [deg]C (59 [deg]F), with peak activity in July. Approximately 150 to 650 eggs will be released per spawning event, hatching within 10 to 14 days. As described above, females prefer a highly organic, vegetative substrate for spawning and will lay their adhesive eggs directly on the submerged vegetation (Pearsons 1989, p. 17, 23; Markle et al. 1992, p. 290; Scheerer 2007b, p. 494). Larvae and juveniles seek dense cover in shallow, warmer regions of offchannel habitats (Pearsons 1989, p. 17; Scheerer 2007b, p. 494).
Habitats Protected From Disturbance

Nonnative Fish

Many species of nonnative fish that compete with or prey upon Oregon chub have been introduced and are common throughout the Willamette Valley, including largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieui), crappie (Pomoxis sp.), bluegill (Lepomis macrochirus), and western mosquitofish (Gambusia affinis). Of the 747 Willamette Valley sites sampled for Oregon chub by ODFW since the beginning of annual survey efforts by the agency in 1991, 42 percent contained nonnative fish. Most of the habitats surveyed that supported large populations of Oregon chub had no evidence of nonnative fish presence (Scheerer 2002, p. 1078; Scheerer 2007a, p. 96; Scheerer et al. 2007, p. 14). The presence of nonnative fish in the Willamette Valley, especially centrarchids (e.g., basses and crappie) and ictalurids (catfishes) is suspected to be a major factor in the decline of Oregon chub and the biggest threat to the species' recovery (Markle et al. 1991, p. 291; Scheerer 2002, p. 1078; Scheerer et al. 2007, p. 18).

Specific interactions responsible for the exclusion of Oregon chub from habitats dominated by nonnative fish are not clear in all cases. While information confirming the presence of Oregon chub in stomach contents of predatory fish is lacking, many nonnative fish, particularly adult centrarchids and ictalurids are documented piscivores (fish eaters) (Moyle 2002, pp. 397, 399, 403; Wydoski and Whitney 2003, pp. 125, 128, 130; Li et al. 1987, pp. 198201). These fish are frequently the dominant inhabitants of ponds and sloughs within the Willamette River drainage and may constitute a major obstacle to Oregon chub recolonization efforts. Nonnative fish may also serve as sources of parasites and diseases; however, disease and parasite problems have not been studied in the Oregon chub.

Observed feeding strategies and diet of introduced fish, particularly juvenile centrarchids and adult mosquitofish (Li et al. 1987, pp. 198201), often overlap with diet and feeding strategies described for Oregon chub (Pearsons 1989, pp. 3435). This suggests that direct competition for food between Oregon chub and introduced species may further impede species survival as well as recovery efforts. The rarity of finding Oregon chub in waters also inhabited by mosquitofish may reflect many negative interactions, including but not limited to foodbased competition, aggressive spatial exclusion, and predation on eggs and larvae (Meffe 1983, pp. 316, 319; 1984, pp. 1,5301,531). Because many remaining population sites are easily accessible, there continues to be a potential for unauthorized introductions of nonnative fish, particularly mosquitofish and game fish such as bass and walleye (Stizostedion vitreurn).

The bullfrog (Rana catesbiana), a nonnative amphibian, also occurs in the valley and breeds in habitats preferred by the Oregon chub (Bury and Whelan 1984, pp. 23; Scheerer 1999, p. 7). Adult bullfrogs prefer habitat similar in characteristics (i.e., little to no water velocity, abundant aquatic and emergent vegetation) to the preferred habitat for Oregon chub, and are known to consume small fish as part of their diet (Cohen and Howard 1958, p. 225; Bury and Whelan 1984, p. 3), but it is unclear if they have a negative impact on Oregon chub populations, as several sites that have large numbers of bullfrogs also maintain robust Oregon chub populations (Scheerer 2008d).

Flood Control

Major alteration of the Willamette River for flood control and navigation improvements has eliminated most of the river's historical floodplain, impairing or eliminating the environmental conditions in which the Oregon chub evolved. The decline of Oregon chub has been correlated with the construction of these projects based on the date of last capture at a site (58 FR 53801; October 18, 1993). Pearsons (1989, pp. 3233) estimated that the most severe decline occurred during the 1950s and 1960s when 8 of 11 flood control projects in the Willamette River drainage were completed (USACE 1970, pp. 219237). Other structural changes along the Willamette River corridor such as revetment and channelization, dike construction and drainage, and the removal of floodplain vegetation have eliminated or altered the slack water habitats of the Oregon chub (Willamette Basin Task Force 1969, pp. I9, II22II24; Hjort et al. 1984, pp. 6768, 73; Sedell and Froggatt 1984 pp. 1,8321,833; Li et al. 1987, p. 201). Management of water bodies (such as reservoirs) adjacent to occupied Oregon chub habitat continues to impact the species by causing fluctuations in the water levels of their habitat such that it may exceed or drop below optimal water depths.

Primary Constituent Elements for the Oregon Chub

Pursuant to our regulations, we are required to identify the known physical and biological features, called primary constituent elements (PCEs), essential to the conservation of the Oregon chub and which may require special management considerations or protections. All areas proposed as critical habitat for Oregon chub are either occupied or within the species' historical geographic range.

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Based on the above needs and our current knowledge of the life history, biology, and ecology of the species and the characteristics of the habitat necessary to sustain the essential lifehistory functions of the species, we have identified four PCEs for Oregon chub critical habitat:

1. Offchannel water bodies such as beaver ponds, oxbows, side channels, stable backwater sloughs, lowgradient tributaries, and flooded marshes, including at least 500 continuous square meters (5,400 square feet) of aquatic surface area at depths between approximately 0.5 and 2.0 m (1.6 and 6.6 ft).

2. Aquatic vegetation covering a minimum of 250 m\2\ (0.06 ac) (or between approximately 25 and 100 percent) of the total surface area of the habitat. This vegetation is primarily submergent for purposes of spawning, but also includes emergent and floating vegetation, and algae which is important for cover throughout the year. Areas with sufficient vegetation are likely to also have the following characteristics:

3. Late spring and summer subsurface water temperatures between 15 and 25 [deg]C (59 and 78 [deg]F), with natural diurnal and seasonal variation.

4. No or negligible levels of nonnative aquatic predatory or competitive species. Negligible is defined for the purpose of this proposed rule as a minimal level of nonnative species that will still allow the Oregon chub to continue to survive and recover.

The need for space for individual and population growth and normal behavior is met by PCE (1); areas for reproduction, shelter, food, and habitat for prey are provided by PCE (2); optimal physiological processes for spawning and survival are ensured by PCE (3); habitat free from disturbance and, therefore, sufficient reproduction and survival opportunities is provided by PCE (4).

This proposed designation is designed for the conservation of PCEs necessary to support the lifehistory functions that were the basis for the proposal. Each of the areas proposed in this rule has been determined to contain sufficient PCEs to provide for one or more of the lifehistory functions of the Oregon chub. Specifically, these areas fall into two groups: areas occupied at time of listing containing PCEs sufficient for one or more lifehistory functions, and areas not occupied at time of listing but that are essential to the conservation of the species and that also contain PCEs for one or more lifehistory functions.

Criteria Used To Identify Critical Habitat

As required by section 4(b)(1)(A) of the Act, we use the best scientific data available in determining areas that contain the features that are essential to the conservation of the Oregon chub. The steps we followed in identifying critical habitat were:

1. Our initial step in identifying critical habitat was to determine, in accordance with section 3(5)(A)(i) of the Act and regulations at 50 CFR 424.12, the physical and biological habitat features (PCEs) that are essential to the conservation of the species as explained in the previous section.

2. We then identified areas occupied by the Oregon chub at the time of listing. Of the 5 populations known at the time of the 1993 listing (58 FR 53801), and the 12 additional sites confirmed by postlisting survey data to be occupied with one or more Oregon chub at the time of listing, 10 still support Oregon chub (Scheerer et al. 2007, p. 2; Scheerer 2008a, p. 2) and contain at least one PCE.

3. Since, based on the recovery plan criteria described above, we found that areas occupied at time of listing were not sufficient to conserve the species, the next step was the identification of any additional sites that were not occupied at the time of listing, but that are currently occupied and contain PCEs, and which may be essential for the conservation of the species. Surveys conducted in 2007 and 2008 indicate that 15 additional sites are currently occupied with one or more Oregon chub (Scheerer et al. 2007, p. 2; Scheerer 2008a, p. 2).

4. Next we identified sites that support introduced populations that also contain the PCEs, and which may be essential for the conservation of the species, which resulted in 11 additional sites being identified (Scheerer et al. 2007, p. 2; Scheerer 2008a, p. 2). Collectively, the above efforts resulted in the identification of 36 occupied sites that met the above criteria.

5. Our final step was to evaluate the 36 occupied sites within the context of the 1998 Oregon Chub Recovery Plan, to determine which areas contained the physical and biological features in the amount and spatial configuration essential to the conservation of the species. This step involved the application of the following criteria:

[cir] Unit 3K, Wicopee Pond.

Three other sites supported naturally occurring populations but were not occupied at the time of listing:
[cir] Unit 1B(1), Geren Island North Channel
[cir] Unit 1B(4), Gray Slough, and

[cir] Unit 3D, Elijah Bristow State Park Island Pond.

In addition, six sites supported introduced populations: [cir] Unit 1C, Foster Pullout Pond
[cir] Unit 2A(1), Russell Pond
[cir] Unit 2B(1), Ankeny Willow Marsh
[cir] Unit 2B(2), Dunn Wetland
[cir] Unit 2B(4), Finley Cheadle Pond, and
[cir] Unit 3A, Fall Creek Spillway Ponds.

Based on this analysis, we are proposing to designate 25 units as critical habitat. Although the 1998 recovery plan calls for establishing and maintaining a minimum of 20 populations, we believe that establishing additional populations will allow the Service to mitigate the potential that some units may become unable to support the species or primary constituent elements over time because of predation issues or other factors.

After applying the above criteria, we mapped the critical habitat unit boundaries at each of these 25 sites. Mapping was completed using a Geographic Information System (GIS), and involved several steps. Critical habitat unit boundaries were delineated to encompass the extent of habitat containing the physical and biological features essential to the conservation of the species that may require special management considerations or protection. Polygon vertices (points where two lines meet) were collected along the annual high water mark at least every 30 meters (98 ft) around the perimeter of the site, and at a greater frequency in areas of complexity or where higher resolution was necessary. The full extent of each pond or slough was mapped; islands were mapped with the same method as the perimeter of the site. At sites where tributaries or channels entered or exited a site, only the extent of suitable Oregon chub habitat was mapped. The extent of chub use in open systems was defined by habitat features and by previous experience sampling in those areas. Habitat features that defined the limit of Oregon chub use in a channel included increased gradient, the absence of aquatic vegetation, and areas where gravel, cobble, or other large substrate was present. We combined the polygon data with information from aerial photos to determine the proposed critical habitat unit boundaries of each site.

Special Management Considerations or Protections

The term critical habitat is defined in section 3(5)(A) of the Act, in part, as geographic areas on which are found those physical or biological features essential to the conservation of the species and ``which may require special management considerations or protections.'' Accordingly, in identifying critical habitat in occupied areas, we assess whether the primary constituent elements within the areas determined to be occupied at the time of listing may require any special management considerations or protections. Although the determination that special management may be required is not a prerequisite to designating critical habitat in areas essential to the conservation of the species that were unoccupied at the time of listing, all areas being proposed as critical habitat require some level of management to address current and future threats to the Oregon chub, to maintain or enhance the physical and biological features essential to its conservation, and to ensure the recovery and survival of the species.

The primary threats impacting the physical and biological features essential to the conservation of the Oregon chub that may require special management considerations within the proposed critical habitat units include: Competition and predation by nonnative fish; the potential for initial or further introduction of nonnative fish; vegetative succession of shallow aquatic habitats; possible agricultural chemical runoff; possible excessive siltation from logging in the watershed; other threats to water quality (including threat of toxic spills, low dissolved oxygen); and fluctuations in water levels due to regulated flow management at flood control dams, as well as low summer water levels.

Some additional threats to the continued survival and recovery of the Oregon chub, such as the potential for reduced genetic diversity due to the low level of mixing between populations, will likely be addressed by direct management of populations (e.g., translocation of individuals) rather than by management of the physical and biological features of the habitat. Such threats, therefore, are not addressed in this section specific to the special management required of the physical and biological features of the proposed critical habitat areas.

Special management considerations or protections are needed in most of the units to address the impacts of competition and predation by nonnative fishes in Oregon chub habitat or to avoid the potential introduction of nonnative fishes into areas occupied by Oregon chub. Predatory nonnative fishes are considered the greatest current threat to the recovery of the Oregon chub. Management for the Oregon chub has focused on establishing secure, isolated habitats free of nonnative fishes. Nonnative fishes are abundant and ubiquitous in the Willamette River Basin, and monitoring and management are required to remove nonnative fishes from Oregon chub habitat when possible, and to protect Oregon chub populations that have not yet been affected by nonnative fishes from invasion.

Special management is needed to reduce or eradicate the threat posed by nonnative fishes already present in the following proposed units:

Special management or protections are needed to prevent the introduction or further introduction of nonnative fishes into the following proposed units:

Although Oregon chub require some aquatic vegetation for cover and spawning, some areas of Oregon chub habitat are threatened by succession to wet meadow systems due to a lack of natural disturbance (such as floods) or excessive siltation. If vegetation completely fills in the open water areas of Oregon chub habitat, these areas are no longer suitable for the Oregon chub. Special management is required to prevent or set back vegetative succession in Unit 3G, East Fork Minnow Creek Pond, to alleviate this threat to the Oregon chub's aquatic habitat.

Some units require special management to avoid the degradation of water quality in Oregon chub habitats due to agricultural chemical runoff. Elevated levels of nutrients and pesticides have been found in some Oregon chub habitats (Materna and Buck 2007, p. 67). The source of the contamination is likely agricultural runoff from adjacent farm fields (Materna and Buck 2007, p. 68). Special management will be needed to reduce the incursion of potentially hazardous agricultural chemicals into Oregon chub habitats and maintain water quality in Units 1B(4) Gray Slough, Unit 2B(2) Dunn Wetland, and Unit 2B(4) Finley Cheadle Pond.

Although Oregon chub utilize fine silty substrates, an overabundance of siltation resulting from activities such as logging poses a threat to Oregon chub habitat by filling in the shallow aquatic areas utilized by the species. Excess sedimentation can also lead to the succession of open water habitats to wet meadow, as discussed above. Special management to alleviate the threat posed by excess watershed siltation due to logging and other activities is needed in Unit 1B(1) Geren Island North Channel, Unit 2A(1) Russell Pond, Unit 2B(5) Finley Gray Creek Swamp, Unit 3G East Fork Minnow Creek Pond, Unit 3J Buckhead Creek, and Unit 3K Wicopee Pond.

Special management is required in several of the proposed critical habitat units to maintain the water quality required by Oregon chub and protect against the impacts of several potential threats to water quality. Many Oregon chub populations occur near rail, highway, and power transmission corridors, agricultural fields, and within public park and campground facilities, and there is concern that these populations could be threatened by chemical spills, runoff, or changes in water level or flow conditions caused by construction, diversions, or natural desiccation (58 FR 53800, U.S. Fish and Wildlife Service 1998, p. 14). Water quality investigations at sites in the Middle Fork and Mainstem Willamette subbasins have found some adverse effects to Oregon chub habitats caused by changes in nutrient levels. Elevated nutrient levels at some Oregon chub locations, particularly increased nitrogen and phosphorus, may result in eutrophication and associated anoxic conditions unsuitable for chub, or increased plant and algal growth that severely reduce habitat availability (Buck 2003, p. 12). Monitoring and special management are needed to ameliorate the effects of excessive nutrient levels in Oregon chub habitats, as well as provide protection against accidental sources of contamination to the extent possible, in the following units:

Although the Oregon chub evolved in a dynamic environment in which frequent flooding continually created and reconnected habitat for the species, currently most populations of Oregon chub are isolated from each other due to the reduced frequency and magnitude of flood events and the presence of migration barriers such as impassable culverts and beaver dams (Scheerer et al. 2007, p. 9). Historically, regulated flow management of flood control dams eliminated many of the slough and side channel habitats utilized by Oregon chub by reducing the magnitude, extent, and frequency of flood events in the Willamette River Basin. Currently, flow management activities impact Oregon chub in many of their remaining habitats by inadvertently raising or lowering the depth of water bodies to levels above or below the optimum for the species. Water depths in the summer may be reduced to levels that threaten the survival of Oregon chub due to flow management in adjacent reservoirs or rivers, or from natural drought cycles. Special management is required to ameliorate the effects of fluctuating or reduced water levels for the Oregon chub in:

In summary, we find that each of the areas we are proposing as critical habitat contains features essential to the conservation of the Oregon chub, and that these features may require special management considerations or protection. These special management considerations and protections are required to eliminate, or reduce to a negligible level, the threats affecting each unit and to preserve and maintain the essential features that the proposed critical habitat units provide to the Oregon chub. A more comprehensive discussion of threats facing individual sites is in the individual unit descriptions.

The designation of critical habitat does not imply that lands outside of critical habitat do not play an important role in the conservation of the Oregon chub. Federal activities that may affect those unprotected areas outside of critical habitat are still subject to review under section 7 of the Act if they may affect Oregon chub. The prohibitions of section 9 against the take of listed species also continue to apply both inside and outside of designated critical habitat. Take is broadly defined in the Act as to harass, harm, wound, kill, trap, capture, or collect a listed species, or to attempt to engage in any such conduct.

Proposed Critical Habitat Designation

The areas we are proposing as critical habitat currently provide all habitat components necessary to meet the primary biological needs of the Oregon chub, as defined by the primary constituent elements. The areas proposed for designation are those areas most likely to substantially contribute to conservation of the Oregon chub, and when combined with future management of certain habitats suitable for restoration efforts, will contribute to the longterm survival and recovery of the species.

Under the Act, we can designate critical habitat in areas outside of the geographical area occupied by the species at the time it is listed only when
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(1) the inclusion of specific areas occupied at the time of listing defined by the essential physical and biological factors are not sufficient to conserve the species; and (2) we determine that those areas outside the geographical area occupied by the species are essential for the conservation of the species.

We have determined that 25 units totaling approximately 53 ha (132 acres) meet our definition of critical habitat for the Oregon chub, including land under State, Federal, other government, and private ownership. Nine of the critical habitat units described below constitute our best assessment of areas determined to be occupied at the time of listing that contain the primary constituent elements and require special management (units 2B(5), 3B, 3E, 3F, 3G, 3H, 3I, 3J, 3K). Because the nine occupied units do not alone contain physical and biological features sufficient to conserve the species, we are proposing an additional 16 units. The other 16 proposed units constitute our best assessment of areas that were not occupied or not known to be occupied at the time of listing but were within the species' historical range, which were found to be essential to the conservation of the Oregon chub. These additional areas include natural and introduced populations. The Critical Habitat Selection Criteria and Special Management Considerations or Protections sections above address why the inclusion of specific areas occupied at the time of listing defined by the essential physical and biological factors are not sufficient to conserve the species; and, for the additional 16 proposed units, why we determine that those areas outside the geographical area occupied by the species are essential for the conservation of the species.
Area 1: Santiam River BasinLinn and Marion Counties, Oregon A. Mainstem

Unit 1A, the Santiam I5 Side Channels: This site consists of three ponds totaling 1.4 ha (3.3 ac), located on a 27ha (66ac) property on the south side of the Santiam River upstream of the Interstate Highway 5 bridge crossing in Linn County, Oregon. The areas containing Oregon chub include a small backwater pool, a gravel pit, and a side channel pond. This unit is owned by the Oregon Department of Transportation (ODOT) and Oregon chub were first observed here in 1997. Although only 22 Oregon chub were counted at the site in 2007, the habitat contains 3 of the 4 PCEs and has exhibited capability of supporting a substantial population of the species based on past survey population estimates of over 500 individuals. The maximum water depth is approximately 3 m (9.8 ft), averaging 1.5 m (4.9 ft), and the temperature was recorded at between 19.5 and 21 [deg]C (60 and 67 [deg]F) on July 30, 2008. The substrate is composed of 80 percent silt and organic material, and there is a variety of emergent and submergent vegetation covering 65 percent of the surface area. Beaver have been observed at this location. This site is at risk of the vegetation expanding to levels detrimental to Oregon chub habitat. The site is periodically connected to the Santiam River, and its water levels can be affected by hydrologic changes in the river, particularly the low summer levels common in the drainage. Competing and predatory nonnative species have been observed; nonnative predators are suspected to be a major factor in the drop in Oregon chub population estimates at this site between the 2006 and 2007 surveys (Scheerer 2008d).

B. North

Unit 1B(1), Geren Island North Channel: This site totals approximately 0.8 ha (1.9 ac) and is located on the grounds of a water treatment facility owned by the City of Salem in Marion County, Oregon. The species was first observed at this site in 1996. Although only 207 Oregon chub were counted at the site in 2008, the habitat contains 3 of the 4 PCEs and has exhibited capability of supporting a substantial population of the species based on past survey population estimates of over 500 individuals. The maximum water depth is 2.2 m (7.2 ft), averaging 1.8 m (5.9 ft), and the temperature was recorded at 26 [deg]C (79 [deg]F) on July 10, 2008. The substrate is composed of 90 percent silt and organic material, and there is a variety of emergent and submergent vegetation covering 65 percent of the surface area. Beaver have been observed at this location. The site is screened and isolated from other water bodies, but water levels are influenced through water releases at Detroit and Big Cliff Dams. Competing and predatory nonnative species have been observed at the site. There is also a risk of excess sedimentation due to logging in the watershed.

Unit 1B(2), the Stayton Public Works Pond: This site totals approximately 0.4 ha (1.0 ac) and is located in and owned by the City of Stayton, in Marion County, Oregon. The species was first observed at this location in 1998. Although only 68 Oregon chub were counted at the site in 2008, the habitat contains 3 of the 4 PCEs and has exhibited capability of supporting a substantial population of the species based on past survey population estimates of over 500 individuals. The maximum water depth is 2 m (6.6 ft) deep, averaging 1.2 m (3.9 ft), and the temperature was recorded at 25.5 [deg]C (77.9 [deg]F) on July 9, 2008. The substrate is composed of 90 percent silt and organic material, and there is a variety of emergent and submergent vegetation covering 100 percent of the surface area. Beaver have also been observed at this location. The site is periodically connected to the North Santiam River and is therefore at risk of low summer water levels and nonnative fish introduction. Competing and predatory nonnative species have been observed at this site.

Unit 1B(3), South Stayton Pond: This site totals approximately 0.1 ha (0.2 ac), is located in Linn County, Oregon, and is owned by the Oregon Department of Fish and Wildlife (ODFW). This site was the location of a 2006 introduction of 54 Oregon chub and a supplemental 2007 introduction of 67 additional individuals. The population is currently estimated at 1,705 individuals and appears to be stable or increasing. The habitat contains all of the PCEs. The maximum water depth is 1.6 m (5.3 ft), averaging 0.9 m (3 ft), and the temperature was recorded at 24.5 [deg]C (76.1 [deg]F) on July 9, 2008. The substrate is composed of 90 percent silt and organic material, and there is a variety of emergent and submergent vegetation covering 100 percent of the surface area. The site is isolated from other water bodies and currently has no competing or predatory nonnative species. Because of the easy public access to the site, it may be at risk of illegal introduction of nonnative fish.

Unit 1B(4), Gray Slough: This privately owned site totals approximately 2.5 ha (6.2 ac) and is in Marion County, Oregon. The species was first observed at this site in 1995. The population is currently estimated at 655 individuals, has been stable for 5 years, and the habitat contains 3 of the 4 PCEs. The maximum water depth is 2.5 m (8.2 ft), averaging 1.2 m (3.9 ft), and the temperature was recorded at 23.5 [deg]C (74.3 [deg]F) on July 31, 2008. The substrate is composed of 100 percent silt and organic material, and there is a variety of emergent and submergent vegetation covering 55 percent of the surface area. Beaver, and also competing or predatory nonnative fish species, have been observed at this location. The site is periodically connected to the North Santiam River and

FOR FURTHER INFORMATION CONTACT

Paul Henson, State Supervisor, U.S. Fish and Wildlife Service, Oregon Fish and Wildlife Office, 2600 SE 98th Avenue, Suite 100, Portland, OR 97266 (telephone 5032316179; facsimile 5032316195). If you use a telecommunications device for the deaf (TDD) call the Federal Information Relay Service (FIRS) at 800 8778339.