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Federal Register / Vol. 86, No. 124 / Thursday, July 1, 2021 / Rules and Regulations
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We present brief descriptions of all units, and reasons why they meet the definition of critical habitat for the Suwannee moccasinshell, below.
Unit 1: Suwannee River, Florida Unit 1 consists of approximately 187
km 116 mi of the Suwannee River and lower Santa Fe River in Alachua, Columbia, Dixie, Gilchrist, Lafayette, Madison, and Suwannee Counties, Florida. The unit includes the Suwannee River mainstem from the confluence of Hart Springs near river kilometer 71 in Dixie and Gilchrist Counties, upstream 137 km 85 mi to the confluence of the Withlacoochee River in Madison and Suwannee Counties; and the Santa Fe River from its confluence with the Suwannee River in Suwannee and Gilchrist Counties, upstream 50 km 31 mi to the rivers rise in Alachua County. The Santa Fe River flows underground for about 5 km 3.1 mi, sinking at OLeno State Park and rising at River Rise Preserve State Park. The lower and upper portions of the Santa Fe River are intermittently connected during high flow events. The riparian lands along stream reaches in this unit are generally privately owned agricultural or silvicultural lands, or State-owned or -managed conservation lands Table 1.
The Suwannee moccasinshell occupies all stream reaches in this unit, which contains most of the physical or biological features essential to the conservation of the Suwannee moccasinshell. However, decreases in stream flow and changes in water quality, especially increased nitrogen loads and algae growth, are recognized issues in all stream reaches within the unit SRWMD 2017, pp. 2627, 4250.
During drought, depressed dissolved oxygen levels and elevated water temperatures may also be degraded in some reaches. Therefore, physical or biological features 3 and 4 are not consistently present in the unit.
Currently, 73 percent of Unit 1 is designated critical habitat for the Gulf sturgeon a migratory fish. Some small urban areas also are located near the two rivers.
Special management considerations and protections that may be required to address threats within the unit include:
Minimizing ground and surface water withdrawals or other actions that alter stream hydrology; reducing the use of fertilizers and pesticides, especially in spring recharge areas and near stream channels; improving treatment of wastewater discharged from permitted facilities and the operation of those facilities; implementing practices that protect or restore riparian buffer areas
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along stream corridors; avoidance of physical alternations to the stream channel and floodplain; prohibiting the removal of pre-cut submerged timber deadhead logs; and establishing and enforcing restrictions on boat speed and length, especially in the lower Santa Fe River. Many of these measures would also be implemented in stream reaches upstream of the unit to adequately protect habitat within the unit. For example, a large surface mining project is proposed adjacent the New River within the upper Santa Fe River watershed. If the mining operation and its associated structures are constructed as currently proposed, we anticipate that physical or biological features 3 and 4 would be negatively impacted to a significant degree within the unit. In addition, groundwater discharge via springs is important to maintaining flows and water quality needed by the species, especially during drought Holcomb et al., 2018, p. 95. Therefore, spring recharge areas and aquifers may also need to be protected in order to fully address threats within the unit.
Unit 2: Upper Santa Fe River, Florida Unit 2 consists of approximately 43
km 27 mi of the Santa Fe River and New River in Alachua, Bradford, Columbia, and Union Counties, Florida.
The unit includes the Santa Fe River from the rivers sink in Alachua County, upstream 36.5 km 23 mi to the confluence of Rocky Creek in Bradford and Alachua Counties; and the New River from its confluence with the Santa Fe River, upstream 6.5 km 4 mi to the confluence of Five Mile Creek in Union and Bradford Counties. The riparian lands along stream channels in this unit are generally privately owned agricultural or silvicultural lands, or are State-owned or -managed conservation lands Table 1. All of Unit 2 is also designated critical habitat for the oval pigtoe a freshwater mussel. The Suwannee moccasinshell was routinely represented in historical collections in the upper Santa Fe sub-basin; however, it is the only mussel species not detected in contemporary surveys. Unit 2 retains the features of a natural stream channel and presently supports a diverse mussel fauna, including several mussel species known to co-occur with the Suwannee moccasinshell. This unit has at least one of the physical or biological features essential to the conservation of the species, and we are reasonably certain that this area will contribute to the conservation of the species. Our specific rationale for this unit can be found below.
This area is essential for the conservation of the species because it
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would improve its resiliency and redundancy of the species, which is necessary to conserve and recover the Suwanee moccasinshell. To improve the species overall viability by increasing resiliency and redundancy, it is important to reestablish Suwannee moccasinshell populations in its former range in the Santa Fe River sub-basin i.e., Unit 2. Presently, nearly the entire population of the species is linearly distributed within the Suwannee River and vulnerable to catastrophic events for example, contaminant spills or severe floods, as well as to random fluctuations in population size or environmental conditions Haag and Williams 2014, p. 48. Therefore, reestablishing populations in Unit 2
would reduce its extinction risk by expanding its current range into areas beyond the mainstem by providing connectivity to already occupied areas, space for growth and population expansion in portions of historical habitat, and refugia areas from threats in the Suwannee River.
Although it is considered unoccupied, portions of this unit contain some or all of the physical or biological features essential for the conservation of the species. Unit 2 possesses characteristics described by physical or biological features 1 and 2 as long reaches of stable stream channel and suitable substrates are present throughout much of the unit.
Unit 2 retains the features of a natural stream channel and presently supports a diverse mussel fauna, including several mussel species that ordinarily co-occur with the Suwannee moccasinshell. Both fish species found to serve as larval hosts for the Suwannee moccasinshell occur within the unit Robins et al., 2018, pp. 317, 336.
Physical or biological features 3 and 4
are degraded in the Unit during some times of the year. Flow levels in the upper Santa Fe River have declined over time, and the river has ceased to flow multiple times since 2000 Johnson et al., 2016, p. 170. An important effect of reduced flows is altered water quality, especially depressed dissolved oxygen levels and elevated water temperatures discussed above under Physical or Biological Features. In 2007, the District developed minimum flow levels to establish flows protective of fish and wildlife habitats and the passage of fish in the upper Santa Fe River SRWMD 2007, entire. The restoration of natural flow levels is a complex issue that will require considerable involvement and collaboration of Federal, State, and local governments and private landowners to implement projects that reduce groundwater
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