FINAL__UCS__EA_8-15-2013_2.pdf

ENVIRONMENTAL ASSESSMENT

FOR UPPER CARSON SLOUGH

RESTORATION AND TRAIL SYSTEM PROJECT

AT ASH MEADOWS

NATIONAL WILDLIFE REFUGE

EA 84550-13-01

Submitted to:

U.S. Fish and Wildlife Service Ash Meadows National Wildlife Refuge HCR 70, Box 610Z Amargosa Valley, Nevada 89020 775-372-5435

Submitted by:

BIO-WEST, Inc.

1063 W. 1400 N.

Logan, Utah 84321 435-752-4202

August 2013 zspruell Text Box This is an Example Environmental Assessment that was performed for another project located at Upper Carson Slough.

Note, this EA has aged ~10 years.

The details in regard to required elements should come from the current NEPA Guidance for the NWRS. Current NEPA Guidance document is titled, "EA. Guidance. 508-Compliant. Jan2025."

The Upper Carson Slough Project included extensive spring restoration work and a new trail system with overlooks, which is similar to the Crystal Spring Outflow Restoration Project.

However, there are aspects to the Crystal Spring Outflow Restoration Project that differ.

This EA is intended to demonstrate the level of analysis that would meet USFWS expectations.

BIO-WEST, Inc. Environmental Assessment

May 2013 i Upper Carson Slough Restoration

TABLE OF CONTENTS

1.0 PURPOSE AND NEED FOR ACTION

1.1 Ash Meadows National Wildlife Refuge Background

1.2 Purpose for Taking Action

1.3 Need for Taking Action

1.4 Decision to Be Made by the Responsible Official

1.5 Scoping and Public Review of the Draft EA

2.0 ALTERNATIVES

2.1 Alternative A (No Action)

2.2 Alternative B (Proposed Action)

2.2.1 Restore Longstreet Spring

2.2.2 Remove Irrigation Pipe from Rogers Spring

2.2.3 Restore Rogers Spring and Longstreet Spring Outflow Channels

2.2.4 Install Removable Fish Barriers and Discharge Measurement Trench on Rogers Spring and Longstreet Spring Outflow Channels

2.2.5 Remove Existing Project Area Hydrologic Barriers within the Upper Carson Slough

2.2.6 Cold Spring Outflow Channel Restoration

2.2.7 Outflow Channel Restoration and Culvert Replacement for the Five Springs Area

2.2.8 Remove Northwest Berm at Peterson Reservoir

2.2.9 Develop Trail System in the Upper Carson Slough

3.0 AFFECTED ENVIRONMENT

3.1 Air Quality

3.2 Threatened and Endangered Species and their Critical Habitat

3.2.1 Ash Meadows Amargosa Pupfish

3.2.2 Ash Meadows Speckled Dace

3.2.3 Devils Hole Pupfish

3.2.4 Southwestern Willow Flycatcher

3.2.5 Yuma Clapper Rail

3.2.6 Amargosa Niterwort

3.2.7 Ash Meadows Blazingstar

3.2.8 Ash Meadows Ivesia

3.2.9 Ash Meadows Milkvetch

3.2.10 Ash Meadows Sunray

3.2.11 Spring-loving Centaury

3.3 Cultural and Historic Resources

3.4 Recreation

3.5 Invasive and Nonnative Plants and Animals

3.6 Hydrology

3.7 Floodplains

3.8 Wetlands

3.9 Migratory Birds

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4.0 ENVIRONMENTAL CONSEQUENCES

4.1 Alternative A (No Action)

4.1.1 Air Quality

4.1.2 Threatened and Endangered Species and Their Critical Habitat

4.1.3 Cultural and Historic Resources

4.1.4 Recreation

4.1.5 Invasive and Nonnative Plants and Animals

4.1.6 Hydrology

4.1.7 Floodplains

4.1.8 Wetlands

4.1.9 Migratory Birds

4.2 Alternative B (Proposed Action)

4.2.1 Air Quality

4.2.2 Threatened and Endangered Species and Their Critical Habitat

4.2.3 Mitigation Measures to Reduce Effects on Threatened and Endangered Species

4.2.4 Cultural and Historic Resources

4.2.5 Recreation

4.2.6 Invasive and Nonnative Plants and Animals

4.2.7 Hydrology

4.2.8 Floodplains

4.2.9 Wetlands

4.2.10 Migratory Birds

4.3 Cumulative Impacts

4.4 Impact Analysis Summary

5.0 CONSULTATION AND COORDINATION

5.1 List of Preparers

5.2 Pertinent Laws, Executive Orders, and Regulations

6.0 REFERENCES

List of Tables

Table 1. Excavation Volume Resulting from Soils Generated during Stream Channel Excavation and Associated Fill Area Based on a Fill Depth Not to Exceed 0.5 foot (0.2 meter)

Table 2. Summary of Impacts by Alternative

List of Figures

Figure 1. Location of Proposed Project, Ash Meadows National Wildlife Refuge

Figure 2. Upper Carson Slough Project Area Overview

Figure 3. Upper Carson Slough Approximate Trail Routes

Figure 4. Rogers Spring–Longstreet Spring Action Area

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Figure 5. Cold Spring Action Area

Figure 6. Five Springs Action Area

Figure 7. Peterson Reservoir Action Area

Appendix A – Response to Comments

May 2013 1 Upper Carson Slough Restoration

1.0 PURPOSE AND NEED FOR ACTION

1.1 Ash Meadows National Wildlife Refuge Background

Ash Meadows is a unit of the National Wildlife Refuge System. Unlike most U.S. Fish and Wildlife Service

(USFWS) Refuges, Ash Meadows was created to “conserve and recover listed endangered, proposed endangered, and candidate plant and animal species found in the area” (USFWS 1984). Ash Meadows National

Wildlife Refuge is a unit of the Desert National Wildlife Refuge Complex (the Refuge). The Refuge encompasses more than 23,000 acres (ac) (9,308 hectares [ha]) and provides habitat for at least 27 plant and animal species found nowhere else in the world. This distinguishes Ash Meadows as having the greatest concentration of endemic species of any area in the United States. Both a recovery plan (USFWS 1990) and conservation plan (USFWS 2009a) have been developed to aid in the recovery of listed species and their habitats.

1.2 Purpose for Taking Action

The purpose of the Proposed Action is to allow the Refuge to comply with the National Wildlife Refuge System

Improvement Act of 1997 “to administer a national network of lands and waters for the conservation, management, and where appropriate, restoration of the fish, wildlife, and plant resources and their habitats within the United States for the benefit of present and future generations of Americans.”

More specifically, the 2009 Desert Wildlife Refuge Complex Comprehensive Conservation Plan and

Environmental Impact Statement (CCP EIS) (USFWS 2009a) calls for the implementation of a variety of management decisions that are intended to improve habitat for endemic species throughout the Refuge and increase visitor services (proposed project). These management decisions include restoring and maintaining viable populations of endemic and threatened and endangered species, and restoring and maintaining the ecological integrity of natural communities within the Refuge.

This Environmental Assessment (EA) is intended to tier to the CCP EIS and provide additional detail and analysis for specific management activities. The management activity addressed in this EA is the restoration of the Upper Carson Slough. Figure 1 shows the location of the proposed project in relationship to Refuge boundaries. Because implementation of the proposed project would directly meet goals 1 and 2 of the CCP EIS for the Refuge (USFWS 2009a), the proposed project achieves compliance with planning on local and national levels and would ultimately allow for more complete protection and restoration of endemic, endangered, and rare organisms.

1.3 Need for Taking Action

Restoration and maintenance of viable wildlife populations, coupled with restoration and maintenance of ecological integrity for natural communities, were identified in the CCP EIS as management goals. However, these goals have not yet been met and specific actions have not yet been taken. Specific actions identified in the

CCP EIS include managing, monitoring, and restoring Refuge habitats (USFWS 2009a).

Springs at the Refuge have been severely impacted by historic anthropogenic activity. Restoration of spring habitats is a critical component in restoration efforts, particularly for endemic fish and invertebrate populations

(USFWS 1985, 1990, 2009a). The Recovery Plan for the Endangered and Threatened Species of Ash Meadows, Nevada lists habitat alteration and exotic species as major threats to listed species (USFWS 1990). The primary objective of the Refuge and its recovery plan is to recover the listed species and their habitats through an ecosystem approach focusing on habitat restoration and the removal of threats. Restoration of springs and historic stream flows is identified as a key element in the recovery of Refuge species.

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Figure 1. Location of Proposed Project, Ash Meadows National Wildlife Refuge.

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The Carson Slough is the major artery of the Refuge ecosystem and the receiving end of a 385-square-mile

(997-square-kilometer [km]) watershed, but anthropogenic alteration of hydrologic processes has resulted in the loss of ecosystem functions. The Upper Carson Slough was drained in the early 1960s, mined for peat, then leveled, tilled and converted to farm fields. The springs feeding into the slough were diverted into irrigation ditches. Numerous dams, levees, roads, and other obstructions to natural flow were constructed. Nonnative aquatic species were introduced, at least two or three endemic species went extinct, and the Ash Meadows speckled dace (Rhinichthys osculus nevadensis) was extirpated from the entire Upper Carson Slough and its spring systems. Vegetation communities have also been altered with the introduction of nonnative and invasive species that often form monocultures and threaten endemic plants.

The outflow channels of Fairbanks Spring and Soda Spring, the first springs to feed into the Carson Slough, and the lower third of the combined Rogers Spring and Longstreet Spring outflows were restored in 2010. This resulted in 4.7 miles (7.7 km) of restored channel, which—coupled with the eradication of nonnative convict cichlids (Archocentrus nigrofasciatus) from the Fairbanks Spring and outflow in 2008—enabled the Refuge to reintroduce the Ash Meadows speckled dace into the Upper Carson Slough for the first time in more than 50 years. Also, in preparation for additional hydrological restoration, approximately 200 ac of nonnative saltcedar

(Tamarix spp.) were extracted from the Upper Carson Slough. In 2011 nonnative sailfin mollies (Poecilia latipinna) were eradicated from the Longstreet Spring system.

The upper sections of Rogers Spring and Longstreet Spring outflows are still largely in irrigation ditches that provide little or no habitat and are in need of restoration as discussed in the CCP EIS. The Longstreet Spring has been enlarged and altered to the point that habitat conditions favor invasive cattail (Typha sp.) and nonnative bullfrogs (Lithobates catesbeiana) over sedges (Carex spp.) and native fish. Five Springs has been seriously altered by channelization and exploration for additional water conducted with heavy equipment. Cold

Spring was also developed to provide irrigation to the agricultural fields.

In addition to altered springs, there are approximately 11 miles (18 km) of barriers to the natural flow through the Upper Carson Slough. These barriers consist of roads, dams, berms and irrigation ditches. (Most irrigation ditches are now dry, but portions of the current flows from Rogers Spring and Longstreet Spring are in ditches included in this total.) The largest barrier to restoration of the natural hydrology and a fully functioning wetland is Mud Lake Dam, which hinders the principal drainage into the Carson Slough. The dam is located adjacent to the Refuge boundary on federal lands administered by the Bureau of Land Management (BLM). Infrequent and high-magnitude floods, especially from the Mud Lake drainage, sustain aquatic habitat in the Upper Carson

Slough by scouring vegetation, transporting sediment, and creating new stream channels. Flood events also transport coarse sediment into the stream channels. Transport and renewal of coarse sediment to the stream channels creates and maintains habitat for aquatic invertebrates and refreshes breeding substrate for native fish species. Although the dam does not impede or influence the frequency and magnitude of flood events due to a large breach in the dam, the location of the breach results in flows being directed toward the Fairbanks sub-basin instead of directly into the Rogers sub-basin where flows were routed naturally prior to dam construction.

Because sediment is deposited behind the dam during floods, it has become not only a seed trap, but a seed source for nonnative species such as saltcedar and fivehorn smotherweed (Bassia hyssopifolia), which then disperse downstream into the Carson Slough. The Refuge has invested time and funding to control these species throughout the Refuge. The Refuge will continue to work with the BLM Las Vegas Field Office to control non-native vegetation and future actions regarding Mud Lake Dam.

In preparation for this multiyear restoration project, detailed elevation data were obtained to determine landscape alteration and aid in describing historic conditions in unaltered areas. Land-based topographic surveys were completed and channel alignments were determined. Hydrologic and hydraulic analyses were also completed and barriers to flow needing removal were identified. All proposed actions have been, and will continue to be, reviewed and approved by the Ash Meadows Recovery Implementation Team (AMRIT), which

May 2013 4 Upper Carson Slough Restoration consists of representatives from the Nevada Department of Wildlife (NDOW); U.S. Fish and Wildlife Service, Southern Nevada Field Office; U.S. Fish and Wildlife Service, Desert National Wildlife Refuge Complex

Office, and Ash Meadows National Wildlife Refuge; U.S Geological Survey (USGS), Desert Research Institute

(DRI); and Southern Oregon University.

The following management plans guide the proposed restoration and recovery actions: Recovery Plan for the

Endangered and Threatened Species of Ash Meadows, Nevada (USFWS 1990), Ash Meadows Geomorphic and

Biological Assessment: Final Report (OBEC SEC 2006), Desert National Wildlife Refuge Complex – Ash

Meadows, Desert, Moapa Valley, and Pahranagat National Wildlife Refuges: Final Comprehensive

Conservation Plan and Environmental Impact Statement (USFWS 2009a), and the Draft Upper Carson Slough:

Restoration Plan (OBEC 2011).

1.4 Decision to Be Made by the Responsible Official

Based on the analysis documented in this draft EA, the Assistant Regional Director of Refuges, Pacific

Southwest Region, must determine whether the proposed action would have a significant effect on the quality of the human environment. If the selected alternative has no significant impacts, a Finding of No Significant

Impact (FONSI) will be prepared.

1.5 Scoping and Public Review of the Draft EA

The CCP EIS outlined the goals and objectives to be accomplished, as well as strategies anticipated to be employed, by the Refuge over the next 15 years, including future restoration efforts. Public meetings to obtain comments on the CCP EIS were held in Las Vegas, Amargosa Valley, Pahrump, Alamo, and Moapa, Nevada, August 4–6, 2008.

In an effort to coordinate with agencies and other stakeholders, Symposia on Ecological Investigations and

Restoration Planning took place in February 2008, February 2009, and February 2010. Each year, more than100 researchers, multiagency staff, governmental partners, and local community members attended. The springs restoration plan and design was open to attendees for comments and discussion, with plan and design changes implemented on a collaborative basis.

Following a notice in the Pahrump, Nevada, newspaper, the Refuge opened a 30-day comment period for the proposed project on 01/30/2013. The public comment period was extended to 03/25/2013. The draft EA was available to the public on the Refuge’s website and at the Refuge Office. We received one comment letter and four emails with comments. We made one change to the project description. Action number 9, the removal of the decommissioned Mud Lake Dam, is no longer part of our proposed action. The project description and impact analysis have been updated accordingly. Appendix A contains our response to comments received on the draft EA.

On October 18, 2011, the culturally affiliated Nuwuvi (Southern Paiute) and Newe (Western Shoshone) nations participated in a presentation and discussion about planned interpretation and restoration projects for the

Refuge, which included the Upper Carson Slough project area. Information and concerns expressed during this meeting were incorporated into the proposed project.

As part of additional scoping efforts, the Refuge hosted three meetings in the community to discuss transportation alternatives within the Refuge. The alternatives discussed included the trail system that is part of the proposed project. The first of these meetings was held locally on March 11, 2010, with the two subsequent meetings held on November 3, 2010. Comments on the proposed trail system were solicited from the public at these meetings.

May 2013 5 Upper Carson Slough Restoration

Issues were identified during scoping by the public, tribes, Refuge staff, consultants, and other agency personnel. These issues included questions and comments regarding threatened and endangered species, air quality, cultural resources, recreation, migratory birds, and wetlands. These issues are analyzed in this EA to determine whether significant impacts would occur to these resources resulting from the proposed project and to compare them with a baseline condition of No Action.

2.0 ALTERNATIVES

2.1 Alternative A (No Action)

Under the No Action Alternative, or Alternative A, no hydrological restoration or trail construction would take place. Restoration of habitat and recovery of species dependent on that habitat would not occur. Efforts to downlist and delist threatened and endangered species would not be as effective without the restoration of the required habitats that are currently degraded or lacking altogether. Habitats for some species could continue to degrade to the point of extinction. None of the eight objectives for species recovery outlined in the recovery plan (USFWS 1990) for threatened and endangered species would be met for the Upper Carson Slough portion of the Refuge. As a result, exotic plants and nonnative organisms would continue to dominate Refuge habitats vital to endemic species for the foreseeable future.

The Refuge would continue to manage threatened and endangered species and habitat as they have in the recent past. Cattails would be removed and Aquatic Invasive Species (AIS) would be trapped as time and staffing allowed.

2.2 Alternative B (Proposed Action)

Alternative B would allow five of the eight objectives outlined in the recovery plan (USFWS 1990) for threatened and endangered species on the Refuge. Components of the preferred alternative aim to restore hydrologic processes (sediment transport, stream channel scour, overland flow) and improve ecosystem function for native species. A proposed trail system would allow visitors to experience and learn about the area while minimizing potential impacts. Figure 2 provides an overview of the proposed hydrologic modifications and Figure 3 illustrates approximate trail routes. More specifically, components of the preferred alternative include the following actions:

1. Restore the spring pool at Longstreet Spring to natural size and shape.

2. Remove irrigation pipe from Rogers Spring to prevent unnatural seepage.

3. Restore the outflow channels from Longstreet Spring and Rogers Spring.

4. Install removable fish barriers on Rogers Spring and Longstreet Spring outflow channels, as well as a discharge measurement trench on Longstreet Spring channel.

5. Remove all remaining ditches, berms, and unnecessary roads that act as hydrologic barriers within the

Upper Carson Slough.

6. Restore the outflow channel from Cold Spring.

7. Restore the outflow channel from Five Springs and replace the culvert that presently conveys flows from

May 2013 6 Upper Carson Slough Restoration

Five Springs beneath the Longstreet Road.

8. Remove the northwest berm at Peterson Reservoir, reducing the overall size of the reservoir while maintaining approximately the same amount of open water (approximate current water level will be maintained).

9. Construct a network of backcountry hiking trails, leading visitors through the unique restored riparian and wetland areas of the Upper Carson Slough.

All of the components of the preferred alternative could reasonably be implemented within a 5-year period.

Funding is currently available for items 1–5 (listed above), and the USFWS is actively seeking funding to complete all of the remaining components.

The remainder of Section 2 provides detailed descriptions for each of the components of the preferred alternative.

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Figure 2. Upper Carson Slough Project Area Overview.

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Figure 3. Upper Carson Slough Approximate Trail Routes.

May 2013 9 Upper Carson Slough Restoration

2.2.1 Restore Longstreet Spring

Figure 4 provides a detailed illustration of the Rogers Spring–Longstreet Spring action area. At present, the

Longstreet Spring source pool is excessively large due to anthropogenic modification, with an average diameter of 61 feet (ft) (approximately 70 ft x 55 ft) (19 meters [m]; 21 m x 17 m) and a maximum depth of 8.6 ft (2.6 m). Excavation of the Longstreet Spring source associated with water development activities prior to Refuge establishment increased the surface area of the source pool. Increased pool volume and surface area have resulted in increased residence time and increased heat loss. In addition, excavation of the spring source created shallow water habitat at the periphery. The shallow water promotes cattail colonization of the source pool. The combination of dense cattail growth and shallow water supports high densities of nonnative aquatic species including crayfish and bullfrog. Prior to eradication efforts at Longstreet Spring in 2011, the shallow water also provided breeding habitat for nonnative fish. Conserving the thermal characteristics of the water associated with a decreased residence time would result in increased thermal habitat downstream from the spring source. This is most important for the recovery of thermal endemic aquatic species that inhabit the Longstreet Spring and outflow channel.

The average discharge rate for Longstreet Spring, which has been declining slightly since 1993, is 2.33 cubic feet per second (cfs). Gourley and Ammon (1997), in their study of the restoration of Kings Spring at the

Refuge, developed a chart comparing spring pool diameter to discharge rate for several spring pools. According to their study, Longstreet Spring should have an average diameter no greater than 30 ft (9 m), indicating that the pool is at least twice as large as it should be.

Prior to reducing the diameter of the spring source pool, the existing water monitoring flume will be removed and the spring source outlet will be shaped with large rocks in order to maintain the desired water level in the spring pool and create the desired aquatic habitat characteristics in the spring source outlet and outflow channel.

The spring pool diameter and volume will be reduced by placing large, locally derived boulders or rock/caliche slabs. The large rocks will be placed in an interlocking pattern and the interstitial space will be filled with gravel and sand to minimize cavities inhabitable by crayfish. The reconstructed spring pool diameter will be approximately 20–30 ft (6–9 m) in diameter. Large rocks will be placed in a manner that creates both vertical and horizontal surfaces below the water surface for the promotion of algal and aquatic invertebrate growth.

These surfaces will also provide breeding territories for the Ash Meadows Amargosa pupfish (Cyprinodon nevadensis mionectes). This same restoration technique was used successfully at Kings Spring in 1997.

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Figure 4. Rogers Spring–Longstreet Spring Action Area.

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2.2.2 Remove Irrigation Pipe from Rogers Spring

Currently, water at Rogers Spring primarily discharges through a Parshall flume into a single outflow channel west of the spring. However, a cast iron pipe (approximately 6–12 inches [15–30 centimeters]) was installed on the north side of Rogers Spring (most likely during the 1960s–1970s agricultural period) to direct spring water via irrigation ditches to fields north and west of the spring source. The pipe still intermittently carries flow from

Rogers Spring. Restoration would include removing pipe on the northern edge of the spring to prevent flows from seeping to an undesired location. This would be accomplished by temporarily pumping the water in

Rogers Spring, if necessary, until it is below the level of the pipe (approximately 2 ft [0.6 m]). The water pump intake would be equipped with 1-millimeter mesh to prevent Ash Meadows Amargosa pupfish from being pulled into the pump; the intake would also be suspended to reduce the likelihood of pupfish eggs from becoming entrained in the intake. The pipe would then be removed with heavy machinery and replaced with compacted soil to prevent future seepage from Rogers Spring to the north. Removing the pipe is expected to benefit the Ash Meadows Amargosa pupfish in the long term because water temperature would remain warmer in the restored (single) outflow channel, improving conditions for reproduction.

2.2.3 Restore Rogers Spring and Longstreet Spring Outflow Channels The Rogers Spring restored outflow channel would re-enter the existing drainage path approximately 3,000 ft

(900 m) downstream from the Rogers Spring source and would connect with the Longstreet Spring outflow approximately 5,000 ft (1,520 m) downstream from the Rogers Spring source. The upper reach of the restored outflow channel for Rogers Spring would be excavated through the old field north of the existing outflow ditch.

The restored channel would bypass the upper portion of the existing flow path/ditch. Bypassing the existing flow path/ditch would allow the restored channel to be excavated in open conditions and reduce the potential for the channel to become overgrown with cattail and common reed (Phragmites sp.), which presently dominate the existing flow path. Minimizing the potential for cattail and common reed growth increases the potential for maintaining high quality aquatic habitat for both the Ash Meadows Amargosa pupfish and Ash Meadows speckled dace.

The Longstreet Spring constructed channel would be excavated to the north of the existing outflow ditch. The constructed channel would bypass the upper portion of the existing flow path. Bypassing the existing flow path would allow the channel to be excavated in open, unobstructed meadow conditions (similar to the upper section of Fairbanks Spring outflow) and reduce the potential of the channel becoming overgrown by cattail and common reed, which presently dominate the existing flow path. As described above, minimizing the potential for cattail and common reed growth increases the potential for maintaining high quality aquatic habitat for both the Ash Meadows Amargosa pupfish and Ash Meadows speckled dace. Constructing the restored channel in a new location would allow water to remain in the existing ditch during restoration activities, while minimizing water management.

The proposed alignments for the restored Rogers Spring and Longstreet Spring outflow channels were selected based on historical (1948) aerial imagery and current LiDAR data. The alignments for the upper 2,000–3,000 ft

(600–900 m) of restored stream channels for both Rogers Spring and Longstreet Spring were selected based on the need to maintain aquatic habitat for target species (native fish and aquatic invertebrates) and avoid areas dominated by invasive vegetation (cattail and common reed). The proposed channel alignments provide the steepest gradient for all possible alignments in the area. A steeper channel would better guarantee that the constructed channel would maintain an open channel free of vegetation overgrowth and provide conditions less suitable for nonnative aquatic species, particularly crayfish which do not withstand higher stream velocities.

Much of the lower reaches of the proposed alignments are dominated by dense vegetation including cattail and common reed. Although it is possible to bypass the dense vegetation along the upper 2,000–3,000 ft (600–900

m) of restored stream channel, due to natural topography it would be necessary to route the restored stream channels through these areas on the lower reaches. Alternatively, this section of the combined Rogers Spring

May 2013 12 Upper Carson Slough Restoration and Longstreet Spring outflows may be left “as is” through the dense vegetation. To reconnect the flows with the section of channel restored in 2010, channel construction would start again below the densely vegetated area.

In general, the desired stream channel dimensions would be 1.5–3 ft (0.5–0.9 m) wide and 13 ft (0.3–0.9 m) deep. The hydraulic conditions desired include a minor amount of variation in water depth within the constructed channel. The desired water depth is 1–3 ft (0.3–0.9 m). Dimensions specific to each channel section were determined using the Hydrologic Engineering Center’s River Analysis System (HEC-RAS v. 4.1)

(USACE 2010), and are provided below.

Rogers Spring Outflow Channel Design Parameters

Discharge at Rogers Spring is approximately 1.4 cfs (628 gallons per minute [gpm])

The upper channel length above the confluence of the Rogers Spring and Longstreet Spring outflow channels is approximately 5,000 ft (1,520 m)

Channel excavation depth is 1.5–2 ft (0.5–0.6 m)

Channel width is 1.5–2 ft (0.5–0.6 m)

Channel water depth:

o Pools are 1–2 ft (0.3–0.6 m) deep o Riffles are 0.5–0.75 ft (0.15–0.23 m) deep o Runs are 1–1.5 ft (0.3–0.5 m) deep

Channel freeboard is 0.5–1 ft (0.15–0.3 m)

Average channel slope is approximately 0.005–0.008

Overall, the channel would have a low degree of sinuosity to minimize vegetation from obstructing the flow. Meanders would be added sparingly to provide variations in channel alignment and, as necessary, to create the desired hydraulic conditions and upstream water depth.

Longstreet Spring Outflow Channel Design Parameters

Discharge at Longstreet Spring is approximately 2.33 cfs (1,045 gpm)

The upper channel length above the confluence of the Rogers Spring and Longstreet Spring outflow channels is approximately 6,000 ft (1,820 m)

Channel excavation depth is 1.5–2 ft (0.5–0.6 m)

Channel width is 2–2.5 ft (0.6–0.76 m)

Channel water depth:

o Pools are 1–2 ft (0.3–0.6 m) deep o Riffles are 0.5–0.75 ft (0.15–0.23 m) deep o Runs are 1–1.5 ft (0.3–0.5 m) deep

Channel freeboard is 0.5–1 ft (0.15–0.3 m)

Average channel slope is approximately 0.007–0.01

Overall, the channel would have a low degree of sinuosity to minimize vegetation from obstructing the flow. Meanders would be added sparingly to provide variations in channel alignment and, as necessary, Rogers Spring–Longstreet Spring Outflow Channel (Lower Channel) Design Parameters

The combined discharge of both Rogers Spring and Longstreet Spring is approximately 3.8 cfs (1,705 gpm)

The lower channel, downstream of the confluence of the Rogers Spring and Longstreet Spring outflow channels, to the previously restored lower channel, is approximately 4,000 ft (1,220 m)

Channel excavation depth is 2–2.5 ft (0.6–0.76 m)

Channel width is 2.5–3 ft (0.76–0.9 m)

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Channel water depth:

o Pools are 1.5–2.5 ft (0.5–0.6 m) deep o Riffles are 0.5–1 ft (0.15–0.3 m) deep o Runs are 1–2 ft (0.3–0.6 m) deep

Channel freeboard is 0.5–1 ft (0.15–0.3 m)

Average channel slope is approximately 0.005–0.007

Overall, the channel would have a low degree of sinuosity to minimize vegetation from obstructing the flow. Meanders would be added sparingly to provide variations in channel alignment and, as necessary,

2.2.4 Install Removable Fish Barriers and Discharge Measurement Trench on Rogers Spring and Longstreet Spring Outflow Channels

Based on existing grade and topography, the preferred locations for the fish barriers are approximately 2,000 and 3,000 ft (600 and 900 m) downstream from the Rogers Spring and Longstreet Spring sources, respectively.

The selected fish barrier design includes a 6- to 12-ft-long (1.8- to 3.6-m-long) section of reinforced concrete box culvert with an open top. The culvert would be installed in line with the constructed stream channel. The culvert would be installed with a flash board system. Stream flow would pass through the culvert and over a locking and tamper-proof flash board fish barrier. The installation of a flash board system would allow adjustment of vertical water surface drop over the barrier and allow the barrier to be permanently or temporarily removed in the future if desired. Inside dimensions of the culvert would be 5 ft (1.5 m) high and 3 ft (0.9 m) wide. The flashboard would allow a range of vertical water surface drop over the structure from 0 to 3 ft (0 to

0.9 m).

A similar open concrete culvert would be installed on the Longstreet Spring outflow channel closer to the spring pool to house in-stream discharge measurement equipment. This culvert would replace the current water monitoring flume, which acts as an unintentional fish barrier limiting immigration into the pool. The water monitoring flume isolates the fish population in the pool and may result in reduced genetic diversity over time

(Martin 2011). A discharge measurement trench is anticipated to alleviate this situation.

A discharge measurement trench may also be installed on the Rogers Spring outflow channel as described above if funding is available. This trench would be used for water monitoring concurrently with the existing water monitoring flume to compare measurements of the two methods prior to removing the flume.

2.2.5 Remove Existing Project Area Hydrologic Barriers

within the Upper Carson Slough

The primary purpose of berm and ditch removal is to remove features of a former irrigation network that function as barriers to hydrologic processes and limit the recovery of ecosystem function. Within the Upper

Carson Slough, excluding Peterson Dam, there are approximately 10 miles (16 km) of these hydrologic barriers.

Figure 2 illustrates the proposed barrier removals.

Existing ditches would be used for dewatering prior to construction of the new/restored Rogers Spring and

Longstreet Spring outflow channels (described in Section 2.2.2). Therefore, the removal of ditches associated with Rogers Spring and Longstreet Spring would be completed after channel construction is finished. It would be necessary to fill numerous former irrigation ditches in the vicinity of the restored Rogers Spring and

Longstreet Spring outflow channels to prevent either channel from drifting or diverting into former irrigation ditches during high flow events.

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All major ditches would be abandoned by filling with adjacent spoil piles that were placed during development of the former irrigation network. Most berms were constructed with soils excavated during the development of an adjacent irrigation ditch. These berms would be lowered and used to fill the adjacent former irrigation ditch.

Berms that were formed with transported materials would be reduced in size and recontoured to promote overland flow. In order to minimize disturbance and subsequent revegetation requirements, these berms would be transformed into low hummocks similar to the surrounding topography while reducing the diversion or impoundment of natural flow patterns. The large berm and ditch between Rogers Spring and Longstreet Spring would be recontoured and the topography restored to promote overland flow and reduce the potential for tamarisk (Tamarix spp.) colonization on the uphill side of the berm.

2.2.6 Cold Spring Outflow Channel Restoration

Cold Spring is a small spring with an average flow of 0.07 cfs (31 gpm). By 1920, the flows from this spring had been collected into an irrigation ditch, and by 1985 were joined with the network of ditches that carried water to extensive agricultural fields. At present, Cold Spring consists of a small spring pool with an adjacent cement pool (tank). Peterson Road currently separates the spring pool from what appears in the 1948 aerial photograph to be the direction of its historic drainage; however, this may only be a remnant of the 1920s-era ditch. No distinct trace of the historic channel remains. Therefore, a new, naturalized channel would need to be constructed. Three alternatives (design options) for the alignment of the Cold Spring outflow channel have been proposed.

Alternatives 1 and 3 (Figure 5) would connect Cold Spring with the outflows from Fairbanks Spring, Rogers

Spring, and Longstreet Spring, maximizing genetic exchange between populations of fish. Alternative 2 would keep the flow separate, thereby affording a refuge from nonnative species, provided that mosquitofish

(Gambusia affinis) and crayfish (Procambarus clarkii) are eradicated by desiccation during reconstruction of the outflow channel. This refuge would be especially beneficial for the Ash Meadows speckled dace, which, more than the Ash Meadows Amargosa pupfish, would thrive in the cooler temperatures of Cold Spring.

Alternative 3 would avoid crossing the upper section of Peterson Road while Alternatives 1 and 2 would require two road culverts or removal of the road entirely.

The ditch that currently transports the Cold Spring outflows and the cement-lined pool would be removed as part of restoration efforts. The section of Peterson Road north of the road accessing the private inholding may be removed to allow Cold Spring to flow without obstruction if either Alternative 1 or Alternative 2 is chosen.

If Alternative 2 is chosen, restoration actions would include efforts to eradicate nonnative aquatic species.

Crayfish and mosquitofish eradication efforts would require the temporary diversion of flow from the existing outflow ditch to an upland area away from all current sources of water. This would involve the excavation

(using machinery) of a diversion channel or, if possible, the collection and transfer of water in PVC pipe from the spring orifice away from the current channel to allow for its complete desiccation.

Whichever alternative is chosen, the newly constructed channel would be excavated using a tracked excavator to minimize disturbance to the site. The channel would be an appropriate size for the low flow (approximately 1 ft [0.3 m] wide) and would be excavated as a dry channel. Depth of the stream channel would depend on the topography of the site, but would be suitable to contain spring flows. After construction of the new channel and completion of crayfish eradication efforts, flow would be diverted to the new channel. Creation of specific habitat types (riffles, diverse substrates, etc.) would then be completed using hand tools to create habitat suitable for native fish and invertebrates prior to their reintroduction. When sufficient algal growth and food supply are observed and confirmed by the USFWS, native fish and invertebrates would be reintroduced sequentially to allow Refuge biologists to monitor reintroduction success. If Alternative 2 is chosen, keeping the

May 2013 15 Upper Carson Slough Restoration

Figure 5. Cold Spring Action Area.

May 2013 16 Upper Carson Slough Restoration flow separate from the rest of the Upper Carson Slough, Ash Meadows speckled dace would be translocated from other systems (Jackrabbit Spring and Bradford Springs, and/or Fairbanks Spring) dependent on the status of each population and recommendations of the AMRIT.

2.2.7 Outflow Channel Restoration and Culvert Replacement

for the Five Springs Area

The Five Springs area has been seriously altered and channelized. A well was installed at one of the springs during the corporate farming period, circa 1970, and the site shows evidence of manipulation by heavy equipment. Aerial photography from 1948 reveals a faint drainage leading away from Five Springs to the west, connecting with the Upper Carson Slough near Cold Spring. This may have been an ephemeral drainage, or a channel with very low flows. In the 1948 photograph, a fence line or ditch cuts through from Longstreet Spring to the south of Cold Spring, which may have been capturing some of the flows from the Five Springs. By the

1980s, flows from Five Springs were contained in man-made earthen ditches that connected with the outflow ditches from Longstreet Spring for use in the agricultural fields.

Figure 6 illustrates preferred alternative actions in the Five Springs area. Today, some of the springs have no pools, and some have small spring pools, mostly overgrown with vegetation. Recent measurements at one of the

Five Springs average 0.06 cfs (26 gpm). The springs flow through a channel to the west, eventually spilling out of the irrigation ditch and into a marshy area where the water is trapped to the east of Longstreet Road. The road and an abandoned agricultural field west of the road severed Five Springs from what appears to have been its historic drainage. Since Longstreet Road provides the only access to the northern part of the Refuge, a culvert would need to be installed to allow the outflow from the Five Springs to cross without backing up and forming a cattail marsh. West of Longstreet Road where the old agricultural field removed all evidence of a channel, a new, naturalized channel would need to be constructed for approximately 2,000 ft (600 m) to direct the flow toward the historic drainage.

As with Cold Spring, any excavation near the spring sources would be accomplished with a tracked excavator to minimize further disturbance. Restoration sequencing would include the salvage of endemic Fairbanks springsnails (Pyrgulopsis fairbanksensis).

2.2.8 Remove Northwest Berm at Peterson Reservoir

Figure 7 illustrates preferred alternative actions at Peterson Reservoir. A report by Threloff (1992) found no documented evidence of a historical wetland in the site of present-day Peterson Reservoir and no wetlands were reported at this site during the 1881 township surveys. A water rights application from 1923, filed by Mary A.

Rogers, mentions the “lime hills” near the present-day reservoir, but makes no mention of a wetland at this site.

Aerial photography from 1948, however, shows a body of water located in what appears to be a natural depression in the site of the present-day Peterson Reservoir, but much reduced in size. Flows exited the natural impoundment in the northwest corner, just north of the sand dunes which form the western margin (OBEC

2011). A 1952 USGS topographic map (Ash Meadows, Nevada and California) shows an intermittent body of water in this same location that is also much smaller than the present-day Peterson Reservoir. By 1985, berms had been constructed along the south and northwest ends of the wetland area, enlarging and deepening it to form Peterson Reservoir. A major flood event in December 2010 breached the berm at the northwest end near the historic (1948) outflow point and seriously eroded the berm along the south end. However, the reservoir still holds more water than it likely did in the mid-1900s (OBEC 2011).

As with most of the impounded water in the Refuge, Peterson Reservoir fills in with invasive cattails and common reed, especially in the shallow, slack water areas of the north and south ends. Historically, seasonal expansion (winter) and contraction (summer) of inundated areas in the Refuge probably kept tall emergent species like cattail from expanding (Vradenburg 2009). To return Peterson Reservoir to a more natural size and reduce the area covered by cattails while still allowing for waterfowl and recreational use, the northwest berm

May 2013 17 Upper Carson Slough Restoration

F ig u re

F iv e S p ri n g s A c ti o n

A re a

May 2013 18 Upper Carson Slough Restoration

Figure 7. Peterson Reservoir Action Area.

May 2013 19 Upper Carson Slough Restoration would be removed, draining the shallow water from the northern-most section. The excavated berm material would be spread over this very shallow, cattail-covered section of the reservoir. This would also allow more water to be released downstream into the Carson Slough through natural outflow channels. Some modifications to or restoration of the severely eroded southern berm may be needed to access the berm on the northwest side of the reservoir.

2.2.10 Develop Trail System in the Upper Carson Slough

An incomparable opportunity exists to educate visitors about the ecological importance and beauty of this wetland oasis by developing an environmentally sensitive backcountry trail system. The exact location of trail features would be determined after restoration of the Rogers Spring and Longstreet Spring outflows and completion of barrier removal (approximate trail routes are illustrated in Figure 3). Trails could be routed to avoid all threatened and endangered plants. The trail system would be designed to maximize the use of existing disturbance corridors and restored linear disturbance areas. The following trails and overlooks are proposed as potential features of the trail system (OBEC FRD 2011):

Upper Carson Slough Loop Trail – An approximately 4.6-mile (7.4-km) backcountry loop trail, of which a little over 1 mile (1.6 km) is an existing Refuge road. The trail crosses the Upper Carson

Slough, winds through mesquite patches along the upper Fairbanks Channel, and returns along the dirt access road.

Fairbanks Spring Spur Trail – A short offshoot from the Upper Carson Slough Loop Trail (0.46 mile

[0.74 km] each way). Leads visitors to Fairbanks Spring.

Rogers/Longstreet Springs Connection Trail – A 1.3-mile (2.1-km) trail from Longstreet Spring to

Rogers Spring, with the option of looping back on Longstreet Road, a dirt Refuge access road (a 2-mile

[3.2–km] loop).

Peterson Reservoir Trail – A 2.8-mile (4.5-km) trail segment beginning near Peterson Reservoir, which winds north along the lower Fairbanks, Rogers, and Longstreet combined flows, and connects to the Upper Carson Slough Loop.

Trailheads and Parking Areas – Four different parking areas and trailheads would allow visitors to access the trails from a variety of locations. Parking areas would be situated to minimize disturbance.

Three trails are located at the location of current parking areas.

Upper Carson Slough Roadside Overlook – A developed overlook viewpoint located at a high point near Rogers Spring and along Longstreet Road. This viewpoint would be accessed via a vehicle pull-off from the road, with short-term parking for two to three cars.

Rogers Spring Overlook – An overlook at the top of a constructed earthen hill, in close proximity to the Rogers Spring parking lot. The hill would be kept small so as not to block morning sunlight from reaching the spring. The pathway to this viewpoint could be made Americans with Disabilities Act accessible.

Peterson Reservoir Overlook – A viewpoint located on top of a hill overlooking Peterson Reservoir and the Upper Carson Slough, which would be accessed via the Peterson Reservoir Trail. The overlook would be relatively undeveloped.

The majority of trail surfaces would consist of primitive earthen pathways and would be approximately 3 ft (1

m) wide. Water crossings and boardwalks would be used in wet or marshy areas. A portion of the proposed

Upper Carson Slough Loop Trail follows an existing dirt road.

May 2013 20 Upper Carson Slough Restoration

2.2.10.1 Earthen Paths

The earthen path portion of the backcountry trail system would be constructed from native soils. The addition of crushed rock or other materials may be necessary in muddy areas.

2.2.10.2 Water Crossings

Small bridges would be installed as needed where trails cross the spring outflow channels. Materials and designs for these bridges are to be determined.

2.2.10.3 Boardwalks

For marsh crossings and areas where seasonal flooding is a concern, multiple options exist, including: primitive split-log boardwalk, traditional wooden-plank boardwalk, metal grate decking, or alternate options.

2.2.10.4 Refuge Access Road

Longstreet Road is currently closed to visitor vehicle traffic after Rogers Spring by a locked gate. A portion of the Upper Carson Slough Loop Trail would follow this dirt road from Rogers Spring to the Soda Spring channel crossing, approximately 1.04 miles (1.67 km) to the northwest. This road would be left in place as an administrative access road. It would be open to visitors by foot traffic only and to vehicles for administrative and maintenance use.

3.0 AFFECTED ENVIRONMENT

This section describes the area in which the proposed project would occur and focuses on those resources that could be affected through implementation of the proposed project. This section does not provide a detailed description of the environment at large, but supplies the needed information for the reader to understand the discussion in Section 4 pertaining to the anticipated changes in the affected environment resulting from implementation of the proposed project.

The project area is within the Refuge’s Amargosa Valley of southwestern Nevada (Figure 1). The arid conditions of the surrounding valley floor and steep and uplifted mountain ranges provide a stark contrast to the lush environment of the Refuge. The project area occurs within Sections 9–11, 15–16, 21–23, and 28–29 of

Township 17 South, Range 50 East, Mt. Diablo Meridian.

The project area ranges in elevation from approximately 2,176–2,295 ft (663–700 m) within the Mojave Desert.

The predominant vegetation community in the project area is saltgrass (Distichlis spicata), Emory’s baccharis

(Baccharis emoryi), screwbean mesquite (Prosopis pubescens), and mesquite (Prosopis juliflora).

As noted, this EA is tiered to the CCP EIS. The affected environment section of the CCP EIS describes the general physical and biological environment, cultural resources, visitor services, and socioeconomic conditions of the Refuge. As such, resource descriptions in the CCP EIS are incorporated by reference.

3.1 Air Quality

The Air Quality section of Section 4.2.1: Physical Environment of the Final CCP EIS (USFWS 2009a) is hereby incorporated into this EA by reference.

Ambient air quality is not currently…