AMENDMENT 0001 - APPENDIX A-C.pdf

DRAFT

HABITAT MANAGEMENT PLAN

for the

SANTA ANA RIVER MARSH

NEWPORT BEACH, ORANGE COUNTY, CALIFORNIA

Prepared by

U.S. ARMY CORPS OF ENGINEERS

LOS ANGELES DISTRICT

May 2021

SAR Marsh HMP May 2021

TABLE OF CONTENTS

1. INTRODUCTION

1.1 Purpose of the HMP

1.2 Site Overview

1.2.1 Location

1.2.2 History

1.3 Stakeholder Agencies

1.4 Elements of the Marsh

1.4.1 Flood Risk Management Elements

1.4.2 Habitat Elements

1.4.3 Habitat Restoration

1.5 Biological Resources

1.5.1 California Least Tern

1.5.2 Light-footed Ridgway’s Rail

1.5.3 Belding’s Savannah Sparrow

1.5.4 Western Snowy Plover

1.5.5 Coastal California Gnatcatcher

1.6 Hydrology

1.7 Baseline Habitat Condition

1.8 Special Considerations

2. MANAGEMENT TASKS

2.1 Management

2.1.1 Biological Species Inventory

2.1.2 Watershed Mapping

2.1.3 *Inspection of Tide Gate Function*

2.1.4 *Water Quality Emergency Response*

2.1.5 *Coordination with Agencies and Stakeholders*

2.1.6 Public Education

2.2 Maintenance

2.2.1 *Trash Inspection and Maintenance*

2.2.2 *Weeding Inspection and Maintenance*

2.2.3 *Fence Inspection and Maintenance*

2.3 Monitoring

2.3.1 *Water Quality Monitoring*

2.3.2 *Topography Monitoring*

2.3.3 *Tidal Range Monitoring*

2.3.4 *Vegetation Monitoring and Mapping*

2.3.5 CRAM Assessments

2.3.6 Eelgrass Surveys

2.3.7 Benthic Invertebrate Surveys

2.3.8 *Breeding and Wintering Bird Surveys*

2.3.9 Fish and Wildlife Inventory

3. ADAPTIVE MANAGEMENT

3.1 Adaptive Management Actions

3.2 Adaptive Management Special Considerations

3.2.1 Planting and Seeding

3.2.2 Rail Rafts

3.2.3 Tern Island

3.2.4 Dredging

3.2.5 Trail Construction

3.3 Climate Change

4. REPORTING

4.1 Plan of Action

4.2 Annual Reports

4.2.1 Results of Surveys and Monitoring

4.2.2 Maintenance Activities

4.2.3 Volunteer and Recreation Events

4.2.4 Adaptive Management

4.2.5 Conclusions and Recommendations

5. RESPONSIBILITIES

6. POINTS OF CONTACT

7. REFERENCES

8. FIGURES

FIGURES

Figure 1. Santa Ana River Marsh Vicinity Map Figure 2. U.S. Geological Survey 7.5’ Newport Beach Topographical Quadrangle Map Figure 3. Santa Ana River Marsh Aerial Photograph, 1938 Figure 4. Surrounding Land Use Map Figure 5. Flood Control and Habitat Elements Figure 6. Drainage Area Map Figure 7. Easements within Santa Ana River Marsh Figure 8. Schedule of Surveys and Monitoring Figure 9. Topographic Cross-Section Locations Figures 10a and 10b. Examples of Artificial Nesting Raft Designs for Ridgway’s Rail

1. INTRODUCTION

1.1 Purpose of the HMP

This Habitat Management Plan (HMP) provides the plan and requirements to guide long-term management, monitoring, and maintenance of the U.S. Army Corps of Engineers’ (Corps) 92-acre Santa Ana River Marsh (Marsh), a feature of the Santa Ana River Mainstem (SARM) Project. The Marsh is adjacent to the Santa Ana River, near the mouth of the river, in Newport Beach, California (Figure 1). Eight acres of the Marsh were acquired and restored as mitigation for the loss of coastal salt marsh due to construction of the SARM Project (USACE 1987; 1988). An additional 84 acres were restored as enhancement under section 906(e) of the Water Resources Development Act of 1986. Initial physical restoration activities were completed in 1992. The Santa Ana River Marsh is now considered a wetland restoration and endangered species habitat “success story” (Zembal and Hoffman 2010). The Marsh provides restored habitat for a variety of coastal salt marsh plant and wildlife species, including federal and state threatened and endangered species such as the California least tern (Sterna antillarum browni; hereafter, terns), western snowy plover (Charadrius alexandrinus nivosus), coastal California gnatcatcher (Polioptila californica californica), Belding’s savannah sparrow (Passerculus sandwichensis beldingi), and light-footed Ridgway’s rail (Rallus obsoletus levipes; hereafter, rails). Continued management is required for the improvement and maintenance of habitat conditions and to minimize disturbance and degradation.

The Corps is the fee owner of the site and has responsibility for long term operation, maintenance, repair, rehabilitation and replacement (OMRR&R). Cost sharing for the OMRR&R of this feature, including implementation of this HMP, is prescribed by the Local Cooperation Agreement (LCA) for the SARM Project. Pursuant to the LCA for the SARM Project, the Corps may undertake the OMRR&R activities, including this HMP, itself through the Operations Division or arrange for another entity to conduct the HMP activities of the feature, through agreement or outgrant. The Corps is responsible for any decisions on actions recommended under this HMP by the manager and will provide oversight to ensure proper and effective management. This HMP was prepared to provide guidance for management, whether the work is conducted by Corps or by others (with Corps oversight), and to specify maintenance and monitoring activities that are needed to sustain the restored marsh ecosystem. This document outlines the tasks to be performed and a schedule for management actions. The activities in this HMP were analyzed pursuant to the National Environmental Policy Act (NEPA). Any adaptive management actions, and O&M dredging and repair activities may require additional or supplemental NEPA analysis.

The Corps has identified the following primary objectives of Santa Ana River Marsh restoration

(USACE 1987):

• Improve California least tern feeding habitat and, in particular, provide terns with suitably sized fish during critical periods in the breeding season.

• Provide the Huntington Beach least tern colony an additional nesting site.

• Provide habitat for the federally listed endangered light-footed Ridgway’s rail.

• Provide habitat for the state listed endangered Belding’s savannah sparrow.

• Increase overall ecological productivity and diversity in the Marsh.

• Increase the value of the Marsh as a nursery area for marine fish.

• Increase the general aesthetic qualities of the Marsh while maintaining access to active oil well operations and minimizing the total surface area dedicated to roads.

The Corps has identified the following goals for the Habitat Management Plan, for continued future management of the Santa Ana River Marsh:

• Enhance habitat suitability for a wide range of native aquatic, intertidal, and terrestrial plant and wildlife species in a dynamic mosaic of habitats, including upland, high marsh, low marsh, mud flats, and sub-tidal channels.

o Minimize the establishment and spread of non-native invasive plant and wildlife species.

o Minimize negative effects to habitat quality from human encroachment, including trash, boating, unauthorized trespass and recreation, and homeless encampment.

• Enhance habitat suitability for listed threatened and endangered birds including, Belding’s savannah sparrow, light-footed Ridgway’s rail, and California least tern.

o Maximize and sustain the suitability of the “tern island” as nesting habitat for

California least tern.

o Enhance and support vegetation cover for Belding’s savannah sparrow and light-footed Ridgway’s rail.

o Minimize effects of predators on nesting birds.

• Acquire and manage baseline information as a basis for future management decisions, noting any change in conditions that could adversely affect natural resources.

o Monitor physical conditions such as water quality, extent of tidal influence, topography/bathymetry, and sedimentation.

• Monitor biological conditions such as presence of plants, wildlife, fish, and benthic invertebrates, marshland ecological function, and special status species.

• Provide for public education opportunities, where compatible with resource management.

The management actions, monitoring and reporting requirements, and adaptive management strategies described within this HMP will help meet these goals for the Santa Ana River Marsh, in order to enhance and protect the restored coastal salt marsh habitat.

1.2 Site Overview

1.2.1 Location

The Santa Ana River Marsh is located just upstream of the mouth of the Santa Ana River, in the city of Newport Beach, Orange County, California. The site is generally bounded by the Pacific Coast Highway and the community of Newport Shores to the south, the Santa Ana River to the west, oil and gas property operated by West Newport Oil to the east, and Talbert Nature Preserve to the north (Figure 1). The property is shown on the U.S. Geological Survey 7.5’ Newport Beach topographic quadrangle map in Section 20, T. 6 S., R. 10 W. (Figure 2). Existing easements within the Marsh are discussed in Section 1.8.

1.2.2 History

History of SARMP

The Santa Ana River Mainstem Project (SARMP) is a regional approach to provide flood control solutions for the Santa Ana River and tributaries within San Bernardino, Riverside and Orange Counties. The SARMP includes construction of Seven Oaks Dam, modifications to Prado Dam, and improvements to the Santa Ana River mainstem from Prado Dam to the Pacific Ocean.

Project construction in the lower Santa Ana River eliminated approximately eight acres of coastal salt marsh. The Corps analyzed the project’s impacts in the Phase II General Design Memorandum/ Supplemental Environmental Impact Statement (GDM/SEIS) for the Santa Ana River Flood Control Project (USACE 1988) and proposed the acquisition and restoration of eight acres of salt marsh as mitigation and an additional 84 acres of salt marsh for habitat enhancement. The Santa Ana River Marsh site, then in use for oil production, was selected as the mitigation/enhancement site.

Land Use History The Santa Ana River was uncontrolled until approximately 1903 when the lower Santa Ana River was first confined to a channel after heavy flooding (Mitchell 2006). Little is known about the composition of the Santa Ana River Marsh area prior to the more recent oil activities, but surrounding vegetation consisted of salt marsh flora and was presumably part of the historic floodplain. This area may have supported a combination of estuary, beach dunes, or coastal prairie habitat. A 1938 aerial photograph shows that the Marsh area was comprised of natural habitat with some roadways and minimal development along the beach (Figure 3).

West Newport Oil owned the land now occupied by the Santa Ana River Marsh as part of a larger 500-acre parcel beginning in 1943 (when oil production began) until the land was acquired by the Corps. The restoration plan for the Marsh was approved in 1989 and the

92-acre parcel was subsequently acquired by the Corps from West Newport Oil (USACE 1988). At the time of purchase, there were both active and abandoned oil wells on the site, which required extensive cleanup of oil contamination (USACE 1988). Restoration was completed by the Corps in 1992.

Current nearby land uses include the Orange County Sanitation District (OCSD) Treatment Plant 2; Huntington State Beach, which includes a protected least tern breeding colony; a series of restored marsh sites managed by the Huntington Beach Wetlands Conservancy; Talbert Nature Preserve; active oil production; and residential development (Figure 4). The oil and gas property to the east (Newport Banning Ranch) has been proposed for re-use as residential development (Newport Banning Ranch LLC 2009).

1.3 Stakeholder Agencies

Management and oversight of the Santa Ana River Marsh is the responsibility of the Corps (landowner) and Orange County Public Works Flood Control Division (OCFCD, the project sponsor). As stated above in Section 1.1, the Corps is responsible for long term operation, maintenance, repair, rehabilitation and replacement (OMRR&R) of the mitigation/enhancement feature. OCFCD is responsible for operation and maintenance of flood control components, including the adjacent levee, the downstream training dike, tidal gates, and outlet pipes along the levee. OCSD is responsible for maintaining culverts beneath the wastewater pipeline and access road, which allow tidal flow between the northern and southern Marsh areas. The city of Newport Beach owns and operates oil wells within the southern Marsh area.

The decision to purchase and restore the Santa Ana River Marsh was made in coordination with numerous additional agencies, including the California Coastal Commission (CCC), the California Department of Fish and Wildlife (CDFW), the US Fish and Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and the California Regional Water Quality Control Board (RWQCB; Santa Ana Region).

1.4 Elements of the Marsh

The Marsh was designed for two main functions: 1) Flood Control and 2) Habitat Replacement and Enhancement. The Marsh elements described below are depicted in Figure 5.

1.4.1 Flood Risk Management Elements

• Flood water storage: the flood storage volume contained within the Marsh between elevations 3.5 to 6.01 feet provides flood protection to adjacent properties when the Lower Santa Ana River is in flood stage or at extreme high tide.

• Tide gates: these must function properly, closing when Santa Ana River storm flows and tides reach elevation 3.5 feet, to keep those waters from diminishing or eliminating storage volume.

• Outlets: outlets drain the Marsh to permit the tide gates to reopen.

• Side drains: these seven pipes with flap gates must also function properly, both to keep high river flows out of the Marsh and to open when Marsh levels are higher than the river, a typical relationship during intense rain events.

• Adjacent levee: the integrity of the levee is critical to flood protection of the adjacent properties.

• Access bridge: the equalizing flows under this bridge are important for the proper functioning of the Marsh and the access over the bridge is necessary for the maintenance of several utilities within the Marsh.

• Access road: this roadway is necessary for utility maintenance as well as Marsh inspection and maintenance.

• Culverts under the access road: these four pipes provide water exchange between the north and south parts of the Marsh and must remain clear.

1.4.2 Habitat Elements

• 92 acres of reconfigured and replanted salt marsh – this configuration and vegetation are the focus of the restoration.

• Tern island – a sand capped island intended to support nesting endangered California least tern.

• Tide gates – their primary function is to allow the water level in the Marsh to fluctuate with the tides, up to a level of 3.5 feet. Their secondary function is to close at the 3.5-foot upper elevation which was established based upon providing 1% annual chance exceedance (100 year) flood storage protection to adjacent residential property.

1 All elevations and/or depths in feet referred to Mean Sea Level (MSL) unless otherwise noted.

1.4.3 Habitat Restoration

The Corps’ Marsh Restoration Report (1987) included plans for the replacement of an existing flood gate, the addition of a second flood gate to ensure tidal flow between the Marsh and the river, grading to create three elevational ranges corresponding to distinct marsh habitats, planting the reconstructed Marsh with native vegetation, and constructing an island intended for California least tern breeding (“tern island”; USACE 1987).

A geotechnical survey found large amounts of crude oil and its derivatives in the soil and exposed on the soil surface. The recommended remediation included soil removal and off-site disposal. Soil removal lowered the surface grade throughout the property and allowed the creation of expanded subtidal and intertidal marshland. After restoration, the City of Newport Beach continued to operate three oil wells on-site, in a 3-acre interest easement (USACE 1987). These oil wells are still operational, owned and maintained by the City. Two other active wells were diverted off the parcel and all other oil production facilities, including concrete pads and pipes, were removed from the site.

Following remediation, the 92-acre Marsh was contoured to create channels, mudflats, and tidal salt marsh habitats in three elevation ranges: lower, middle and high marsh habitat (USACE 1987). The restoration process reconfigured much of the higher elevations of the site into lower and better draining forms. The approximately 8-acre island intended to support nesting of the endangered California least tern breeding was also constructed using a design that replicated a “search image” of a least tern nest site across the river at Huntington State Beach (USACE 1987). The island was designed to provide enough potential open nesting habitat to support a nesting California least tern colony, based on estimates of average colony size. The Marsh also includes a few acres of miscellaneous uses (city oil easement, access roads, etc.).

Two new tide gates were installed along the eastern bank of the Santa Ana River (USACE 1987) to allow for tidal flows into the Marsh (Figure 5). An older tide gate was replaced with a double five-foot diameter gate at the downstream end of the Marsh. A second gate, measuring six feet by three feet, was installed 1,850 feet upstream of the first gate. The second gate was added to increase tidal flow between the river and upper Marsh area

(USACE 1987).

Following flood gate installation, non-native plants were eradicated and the area was planted with native salt marsh flora, such as California cordgrass (Spartina foliosa) and pickleweed (Salicornia pacifica) (USACE 1987). Planting conformed to the three elevation zones that were graded. Some colonization by these plants was expected to occur at the edges of the tern nesting island (USACE 1987). Un-contaminated, excavated material was deposited on the beach areas down-coast of the river mouth to replenish the existing beach, and material contaminated with oil was disposed of at a landfill facility (USACE 1987).

In 2013 and 2017, the Corps dredged the Marsh channels to partially restore design depths established when the Marsh was built and to improve tidal circulation throughout the Marsh to prepare the Marsh to enter the OMRR&R phase. Not all channels were fully excavated compared to initial design conditions. Continued monitoring outlined in this HMP will determine if and when additional channel maintenance may be required, as described in section 3.2.4.

1.5 Biological Resources

Vegetation at the Santa Ana River Marsh is a combination of salt marsh habitat, dominated by pickleweed and cordgrass, open intertidal flats, and subtidal channels. As designed, the Marsh was restored with three elevation zones:

• Low zone – This zone ranges from elevation 0 feet to 2 feet above sea level. It was planted with Pacific cordgrass, which will tolerate the extensive inundation in salt water with relatively short aeration.

• Middle zone – This zone ranges from elevation 2 feet to 6 feet. In the northern “panhandle” of the Marsh, this zone was planted in pickleweed, which tolerates the relatively shorter inundation and longer aeration times of this zone. In the southern Marsh, undisturbed pickleweed populations spread to infill disturbed Marsh areas.

• High zone – This zone consists of elevations above 6 feet. It was planted with coastal sage scrub species: 20% California brittlebush (Encelia californica), 30% California buckwheat (Eriogonum fasciculatum), 30% California sagebrush (Artemisia californica), 10% bladderpod (Isomeris arborea), and 10% box thorn (Lycium californicum).

Each of these habitats is important for feeding and breeding of intertidal and upland wildlife species. These habitats are also suitable to support several federally and state threatened and endangered species. The Santa Ana River Marsh supports nesting of two listed threatened and endangered birds: the Belding’s Savannah sparrow (State Endangered) and the light-footed Ridgway’s rail (Federal and State Endangered). The Marsh also provides suitable foraging habitat for the California least tern (Federal and State Endangered) in close proximity to the large nesting colony at Huntington State Beach. Other listed species that have been observed in the vicinity of the Marsh include the western snowy plover (Federally Threatened) and coastal California gnatcatcher (Federally Threatened).

1.5.1 California Least Tern

California least tern nesting has not been documented at the Santa Ana River Marsh since restoration in 1992. On the tern island, excessive vegetation, inconsistent vegetation management efforts, and nearby raptor perches (palm trees, power poles) have likely rendered nesting habitat unsuitable. In the summer of 2018, consistent vegetation management was implemented on the tern island and California least terns were observed prospecting the site late during the breeding season. It is expected that with continued vegetation management California least terns may attempt nesting on the tern island.

The Marsh may still be important to least terns for other aspects of their life histories, including

(1) pre-nesting overnight roosting habitat away from nesting colonies; (2) feeding habitat during nesting; (3) feeding habitat post-fledging, when protected waters are important; and (4) post-fledging roosting or loafing habitat.

In 2016, approximately 292 to 337 California least tern were identified at the nearby Huntington State Beach Colony, resulting in 348 nests and 100 to 123 fledglings produced. The number of nesting attempts in 2016 is one of the lowest since Santa Ana Watershed Association (SAWA) began monitoring the colony in 2008, with 2013 having the least with 347 nesting attempts. On a statewide level there has been a downward trend, with individual colonies experiencing variations and fluctuations in total nesting attempts. The Huntington State Beach colony has experienced great fluctuation over the last ten years, with a high of 712 nest initiations in 2011, and a low of 347 initiations in 2013. Pre-term abandonment continues to be the highest cause of nest mortality, with depredation being the second highest cause of nest failure (SAWA 2016).

1.5.2 Light-footed Ridgway’s Rail

Light-footed Ridgway’s rail was first detected in the Marsh in 2006 with 4 pairs and these 4 pairs were detected again in 2007. From 2010 to 2012, 6 pairs were detected, and in 2014, 9 pairs were detected. In 2015 and 2016, a new high of 12 pairs were detected, but in 2017 only 3 pairs were detected (Zembal et al. 2018). More rails may have been present, but the decline in detection may have been due to noise and activity associated with dredging in the Santa Ana River mainstem channel by Orange County throughout the 2017 breeding season. The rails primarily nest in the northern “pan-handle” of the Marsh where cordgrass is prevalent. Residents and dogs heavily impact the southern Marsh area, but 1 pair was detected there in a large patch of cordgrass in past years (not seen in 2017 or 2018; Zembal et al. 2016, 2017, 2018).

1.5.3 Belding’s Savannah Sparrow

Belding’s savannah sparrow was first detected in the Marsh in 1996, with 17 pairs (Zembal and Hoffman 2002). Subsequent surveys in 2001 detected 36 pairs, in 2006 detected 34 pairs, and in 2010 detected 29 pairs (Zembal and Hoffman 2010). More recently, in 2015, surveys detected 49 territories. The sparrows primarily nest in the pickleweed in both the northern and southern Marsh.

1.5.4 Western Snowy Plover

Historically, western snowy plovers nested in Orange County from Upper Newport Bay to Anaheim Bay. Currently, Bolsa Chica Ecological Reserve is the only place in Orange County to host an annual breeding population of plovers. However, in 2018, for the first time in 50 years, two pairs of snowy plovers successfully fledged four chicks at Huntington State Beach (USFWS 2018).

1.5.5 Coastal California Gnatcatcher

Coastal California gnatcatcher inhabit the bluffs at Newport Banning Ranch, adjacent to the Marsh. During 2009 surveys at Newport Banning Ranch, 17 territories were detected (SNBR 2012). A gnatcatcher was recorded at the Marsh during winter bird surveys in 2007/2008 in the Atriplex on the northern edge of the access road, near the levee (SAWA 2010). The gnatcatcher was observed in generally unsuitable habitat and, given the season of the occurrence, was likely a dispersing individual.

Critical habitat for coastal California gnatcatcher occurs at the Marsh in Unit 7, on the adjacent Newport Banning Ranch property (USFWS 2007). No critical habitat occurs within the project area.

1.6 Hydrology

The Marsh is separated into a northern “panhandle” area and a southern area by the utility easement access road, which limits tidal exchange between the two Marshes. During construction of the Marsh, two new floodgates were installed along the eastern bank of the Santa Ana River to allow for tidal flows into the Marsh, while culverts were installed under the access road to improve the flow between the northern and southern Marshes (Figure 5).

The two tidal gates automatically control the flow of water in and out of the Marsh and they can be closed during riverine flooding events. The Marsh, as restored, receives a full tidal variation from 1.5 to 3.5 feet MSL elevations via the tidal gates, which close at approximately 3.5 feet MSL, and reopen when waters recede to an elevation below 1.5 feet MSL (USACE 1987). The upstream and downstream gates provide better opportunity for water circulation when the water surface elevations at these locations present adequate surface water head differential.

Tidal exchange between the north and south Marsh are limited due to the elevation constraint posed by the Orange County Sanitation District sewer lines under the access road. The elevation to the top of the sewer lines is approximately 1.2 feet MSL; tidal exchange will not occur when the tides of both Marshes are below that elevation (USACE 1987). Concrete headwalls were installed to provide additional drainage outlets, and to maximize the potential of tidal inundation circulation. In the northern Marsh, an access bridge was constructed to replace an existing access road that supported a Chevron oil pipeline. This bridge was installed to support the pipeline while still providing tidal exchange to the Marsh area to the north of the pipeline.

The Marsh includes the 8-acre tern island which is nearly level at 8 feet elevation (well above the tidal inundation levels). The remainder of the Marsh is divided by elevation in three zones: Low (0 to 2 feet elevation), Middle (2 to 6 feet elevation), and High (over 6 feet elevation). It is criss-crossed with small 36-inch wide by 18-inch deep “Sprite Ditches” for effective drainage at low tides.

During storms, the Marsh receives a significant inflow of “fresh” or low salinity water. The low-lying areas of the Marsh and adjacent oil property are subject to inundation due to the local runoff, and backflow from the Santa Ana River Channel. The approximate drainage area boundary is shown in Figure 6 (taken from USACE 1987). Runoff from the east drains westward into the Marsh area but is impeded due to the earth berms constructed near the boundary to the oil fields. During extreme riverine flooding, the tidegates prevent flooding in nearby Newport Shores community and minimize prolonged inundation of the wetland vegetation, but also decrease the flow of water while increasing the ponding from local runoff.

Water quality in the Marsh is most affected by the tidal exchange between the Marsh and Santa Ana River Channel and riverine flooding events.

1.7 Baseline Habitat Condition

The existing conditions as described in the EA and HMP reflect the baseline condition for the purposes of implementation of the HMP. The lower Marsh was dredged in 2013, and the downstream tide gate was dredged in 2017 to remove sediment deposition blockages and restore circulation and hydrologic function. The Corps minimized direct effects to habitat in coordination and consultation with USFWS. Orange County Public Works performed a large-scale dredging in the Santa Ana River channel adjacent to the Marsh in 2016.

In recent years, the Marsh has been supporting expanding eelgrass habitat. Pickleweed and cordgrass habitat support listed Belding’s savannah sparrows and light-footed Ridgway’s rails, however rail populations have declined in recent years. Declines may be due to disturbance during dredging or more frequent human and/or domestic dog trespass.

Weeding and trash removal was performed until spring 2019 to improve habitat for nesting terns, however to date terns have not nested on the island.

Past volunteer maintenance events included tern island weeding in December 2008, and California Coastal Commission’s (CCC) Coastal Cleanup Day trash cleanups in 2017, 2018, and 2019.

Continued, regular maintenance including weeding and trash removal, is anticipated to sustain and improve Marsh habitats for threatened and endangered species. Monitoring of hydrology, habitat, and wildlife use will provide indicators of decline in habitat quality, allowing for adaptive management actions to address problem areas. Regular inspections, outreach, and management are anticipated to help prevent or reduce trespass and reduce disturbance to threatened and endangered wildlife.

1.8 Special Considerations

A portion of the Marsh is within the city limits of Newport Beach. Semeniuk Slough, a back channel along the southern edge of the Marsh, is over tidelands not acquired by the Federal Government (Figure 5). Residences within the city of Newport Beach are located along the southern bank of the Semeniuk Slough, outside the project site, and have direct access from their property into the channel. Many of the properties have docks, and in addition to wading and swimming, small non-motorized boats or stand up paddle boards are commonly used in the channel.

The city of Newport Beach owns and operates three oil wells within the Marsh, and maintains oil wells, oil transmission lines, and access roads within the Marsh (Figure 5). Crews access the site on a daily basis to operate and maintain oil production facilities and access roads, which are located within easements acquired by the City prior to acquisition of the Marsh by the Federal Government. The above properties, easements, and rights were not acquired by the Federal Government.

Additional agencies have easements within the Marsh. The Orange County Sanitation District operates and maintains a wastewater pipeline that crosses the Marsh property under the access road that bisects the northern and southern Marsh areas (Figure 5). Coordination of management actions with the City, interested agencies, and local homeowner associations is described in Section 2.1.5. Figure 7 depicts other easements within the Marsh. If the Corps pursues an out-grantee for management of the Marsh, the Corps would provide additional easement information to the manager to coordinate management activities at that time.

2. MANAGEMENT TASKS

Management actions under this HMP include coordination, monitoring, surveying, and maintenance. A schedule of proposed frequency/timing of monitoring and maintenance activities is included in Figure 8. HMP implementation, including monitoring and maintenance activities, are subject to availability of funds. Critical monitoring and maintenance tasks are designated with an asterisk to indicate their priority.

The site manager will also implement adaptive management strategies to maximize the restoration and natural functioning of the Marsh ecosystem, as discussed in Section 3.

Management actions will be documented in regular reports, as discussed in Section 4. Should monitoring results indicate a substantial decline in habitat quality, the manager will examine potential causes, plan and integrate adaptive management actions, and coordinate with the Corps.

2.1 Management

2.1.1 Biological Species Inventory

The manager shall compile a list of past studies and reports generated on plants, invertebrates, and wildlife in the Marsh, as well as a checklist of species, in order to establish an inventory of known plant and wildlife species. The report list and species inventory shall be updated every 5 years to document trends in species occurrence.

• Frequency: Once during the first year, with updates every 5 years thereafter.

• Reporting: The biological species inventory, including lists of reports and studies, will be compiled and submitted with the first year’s annual report, and subsequent annual reports in years the inventory is updated.

2.1.2 Watershed Mapping

To document non-tidal water sources to the Marsh, the manager will identify all storm drains or surface water drainage from surrounding lands that may enter the Marsh, and will identify watershed boundaries and potential sources of toxins or pollutants that may originate within these watersheds.

• Frequency: Once during the first year, with updates every 5 years thereafter.

• Reporting: The watershed information, including maps of watershed boundaries and lists of potential pollution sources, will be compiled and submitted with the first year’s annual report and subsequent annual reports in years the mapping is updated.

2.1.3 *Inspection of Tide Gate Function* The tide gates and culverts will be visually inspected annually at both high and low tide to ensure uninhibited tidal flows in both directions. Inspections will include the downstream tide gate near the southwestern corner of the Marsh, the upstream tide gate just north of the pipeline easement access road, and the series of culverts beneath the access road that connect the northern and southern Marsh.

If tide gates, culverts, and/or trash screens are obstructed or are not functional, the manager will contact the Corps and OCFCD to arrange for prompt repairs. Maintenance of the tide gates and associated structures is the responsibility of OCFCD. The manager will re-inspect the tide gates or culverts to verify repairs and will maintain notes on persons and agencies contacted, dates of communications, dates of repairs, and any follow up actions. Contact information for OCFCD is listed in Section 6.

• Frequency: Annually.

• Reporting: Paper or electronic notes on tidal gate inspections and repairs will be maintained by the manager and summarized in each year’s annual report.

2.1.4 *Water Quality Emergency Response* If the manager is notified of any spill event that could threaten Marsh resources, such as oil or sewage releases, the manager will coordinate immediately with the Corps. The Corps will be responsible for notifying other appropriate agencies, including OCFCD if the tide gates should be closed. If immediate response is needed, the manager may contact OCFCD directly.

• Frequency: As needed.

• Reporting: If a spill occurs, the incident will be reported to the appropriate resource agencies, and will be included in each year’s annual report, along with any recommendations for clean up or restoration.

2.1.5 *Coordination with Agencies and Stakeholders* Prior to implementation of the HMP, the site manager shall coordinate management actions with other agencies and stakeholders with an interest in the Marsh to maximize the knowledge base regarding restoration, surveying, and monitoring techniques and strategies, and to complement other such activities in the area.

Annually, within 3 months after the release of the annual report, the site manager shall host a meeting with these agencies to discuss the management actions that have been implemented, the results of these actions, lessons learned, and problem areas. Strategies for adaptive management that may be needed to remedy problem areas shall also be discussed (see Section 3).

The invited agencies and stakeholders shall include, but are not limited to, the Corps, USFWS, CDFW, RWQCB, CCC, NMFS, OCFCD, OC Water District (OCWD), and the Santa Ana Watershed Association (SAWA). Lack of attendance by any invited agency or stakeholder other than the Corps shall not prevent the meeting from occurring. A Corps representative must be present and meeting content coordinated in advance.

• Frequency: Annually.

• Reporting: The meeting details will be documented in each year’s annual report.

2.1.6 Public Education

2.1.6.a Signage Inspection and Maintenance

Interpretive signage on the levee bike trail and no trespassing signage in the Marsh will be inspected annually and maintained as needed. Any graffiti will be removed, and any damaged or degraded signage will be replaced.

• Frequency: Inspection annually with as needed maintenance.

• Reporting: Inspections and maintenance activities will be documented in each year’s annual report.

2.1.6.b Additional Signage Installation

Two additional interpretive signs will be designed, printed, and installed along the Marsh at the northern Marsh boundary and adjacent to the downstream tide gate. Content of the interpretive signs may be at the discretion of the manager, which could include information related to historic pre-development conditions, light-footed Ridgway’s rail and cordgrass habitat, and/or sensitive coastal wetlands. Additional signage will be maintained with existing signage, as in Section 2.1.6.a.

Telescope viewers may also be installed at strategic points along the levee, in coordination with OCFCD.

• Frequency: Installation of signage within the first 3 years. Inspection annually with as needed maintenance (see Section 2.1.6.a).

• Reporting: Installation will be documented in the annual report for the year in which it is performed. Inspections and maintenance activities will be documented in each year’s annual report.

2.1.6.c Community Outreach

The site manager will meet with the public (resource agencies, local city and county agencies (e.g., City of Newport Beach, OCFCD, OCSD), neighboring land owners (e.g., Newport Banning Ranch, West Newport Oil), local libraries, local non-profit organizations (e.g., Audubon, Surfrider), and community associations that may be affected by the project (e.g., Newport Shores Community Association, West Newport Beach Association) once per year, or less frequently as outreach is needed, to discuss trends in Marsh biological resources and species use. Meeting dates and location will be coordinated with the Corps, who will be notified to participate in the meeting.

The manager will also perform community outreach with the residents adjacent to the Marsh, with a focus on discouraging trespass and unleashed dogs, which disturb nesting birds, including threatened and endangered species.

• Frequency: Annually, or less frequently as community outreach is needed.

• Reporting: The meeting and outreach details will be documented in each year’s annual report when they occur.

2.1.6.d Community Volunteering and Recreation

The site manager may host supervised volunteer events (i.e., trash cleanups, weeding, planting) and supervised passive recreation events (hiking, nature tours, bird watching).

Volunteer and recreation events must be overseen by the Corps and/or site manager, must comply with environmental laws and regulations, and must avoid impacts to endangered species and their habitats (tern island, cordgrass habitat, pickleweed habitat). Managed volunteer and recreation events shall be held between September 16 and February 14 to avoid the nesting season for birds.

Implementation or creation of public access and/or trails would be subject to review and approval from the Corps, non-federal sponsors, environmental resource agencies, and other impacted agencies and stakeholders including, but not limited to, OCSD, OCFCD, City of Newport Beach, and Newport Shores Community Association (NSCA).

Additional NEPA and ESA (Endangered Species Act) compliance would also be required.

• Frequency: As planned, outside nesting season.

• Reporting: Volunteer and recreation events will be documented in each year’s annual report.

2.2 Maintenance

2.2.1 *Trash Inspection and Maintenance* Bi-monthly (i.e. every other month) outside of nesting season (3 months annually), the accessible intertidal areas will be walked over to collect litter or other debris. Inspection will also be performed at this time to identify habitat damage by erosion, vandalism, or other causes, and to locate trails or other trespass damage in need of repair. The manager will evaluate the site for trespass including visual inspections for signs of use or damage (construction of ramps, barriers, or forts; presence of planted non-native plants; etc.).

Periodically, on an as-needed basis, litter clean-up may be conducted from a non-motorized boat for better access. Human disturbance will be avoided in sensitive species breeding habitat during nesting season, and litter removal from those areas will be postponed. Trash will be disposed of properly at an off-site location.

If the manager observes trespass or evidence of trespass, the manager will coordinate with the Corps Operations Division for enforcement.

• Frequency: Bi-monthly outside of nesting season.

• Reporting: Trash maintenance and inspection activities, including needed repairs, will be documented in each year’s annual report.

2.2.2 *Weeding Inspection and Maintenance* The manager will remove non-native invasive species, including but not limited to Algerian sea lavender (Limonium ramosissimum), iceplant (Carpobrotus sp.), and non-native grasses, to benefit habitat quality and special status species. Weeding will be performed by individuals familiar with southern California native salt marsh species and weed species and able to distinguish weed seedlings and juveniles from the native seeded and planted species.

Methods may include mechanical removal or chemical removal with herbicide(s) approved by the Environmental Protection Agency for use in aquatic environments and demonstrated to be effective in treating the target species. Vegetation removed mechanically will be transported off-site to a licensed landfill or composting facility. Vegetation removal must be completed between September 16 and February 14, to ensure no disturbance to nesting birds.

Weeding of the California least tern island specifically would be performed as described below.

• Frequency: Three times annually, outside nesting season, for the first 5 years.

Annually, prior to nesting season, thereafter.

• Reporting: Weeding activities and species removed will be documented in each year’s annual report.

2.2.2.a *California Least Tern Island Maintenance*

To improve and maintain suitable California least tern nesting habitat on the tern island and to minimize potential cover for predators, the manager will monitor and assess native and non-native vegetation cover on the tern island (see vegetation mapping in Section 2.3.4), remove non-native vegetation from the island (see weeding maintenance in Section 2.2.2), and maintain cover of native vegetation on the top, flat portion of the island that is consistent with the species needs and percent cover at the adjacent Huntington State Beach colony. Temporary access ramps (i.e. gang planks) may be placed to span the wetted Marsh channel to improve access to tern island, as needed.

At the Huntington State Beach colony, raking has occurred sporadically since 1985. The nesting area typically supports a widely spaced and low-stature population of beach primrose (Camissoniopsis cheiranthifolia), and some sparse beach morning-glory (Calystegia soldanella), sea rocket (Cakile edentula), and beach sand verbena (Abronia umbellata). Currently, the vegetation is strategically cleared to maintain approximately 25% bare sand and varying levels of vegetative cover. The vegetation is removed in a grid pattern so that a strip is raked every four years, allowing for various amounts of vegetative cover (SAWA 2016).

Based on vegetation mapping and site conditions, the manager will assess the suitability of the least tern island for nesting prior to each nesting season. Vegetation removal shall be directed based on the professional judgment of an ornithologist familiar with California least tern breeding habitat. The top of the least tern island shall be maintained free of dense vegetation. Percent cover of native vegetation on the least tern island shall be maintained between 5% and 25%. Vegetation removal must be completed between September 15 and February 15 to ensure no disturbance to nesting birds. Any vegetation removed will be transported off-site to a licensed landfill or composting facility.

• Frequency: Weeding of the California least tern island three times annually, outside nesting season, for the first 5 years. Annually prior to nesting season thereafter.

• Reporting: Tern island nesting suitability and maintenance activities, including weeding, species removed, and native species maintained, will be documented in the annual report. Proposed future maintenance and any recommendations for tern island management will also be described.

2.2.3 *Fence Inspection and Maintenance* The perimeter fence surrounding the Marsh and the fence surrounding the tern island will be inspected annually to identify any needed replacements and repairs. Maintenance will be performed on the fence as needed. The fence is intended to prevent trespass onto federal land and to prevent access to the tern island by non-native predators, including domestic and feral dogs and cats, and red foxes.

Additional fencing installation or repairs must be scheduled outside the breeding season to avoid impacts to nesting birds, eggs, or nestlings. Fencing installation along Marsh roadways will be coordinated with agencies that have easements on the road, including City of Newport Beach and OCSD. Any impacted areas will be restored.

Other potential fencing materials and designs may be suggested prior to replacing/repairing the existing fence. Regardless of design, any future replacement fence must minimize potential that predators such as kestrels, crows, or loggerhead shrikes could view the tern island’s surface from fence posts, as these species prey on least terns.

• Frequency: Inspections annually. Installation and maintenance as needed. Installation and maintenance may occur during nesting season if a qualified biologist is on-site to monitor work and ensure work does not impact potential nests/nesting habitat.

• Reporting: Inspections and fence replacements will be documented in each year’s annual report.

2.3 Monitoring

2.3.1 *Water Quality Monitoring* Approximately five permanent monitoring stations shall be established in the Marsh to evaluate water quality trends and identify issues that may impact persistence of native plant species and impacts to wildlife species.

Water quality parameters to be monitored include, but are not limited to, water temperature, dissolved oxygen (DO; percent, saturation, and mg/L), turbidity (neophelometric turbidity units [NTUs]), percent transmittance, total suspended solids (TSS; mg/L), total recoverable petroleum hydrocarbons (TRPH; mg/L), pH levels, conductivity (uS/cm), and salinity (mg/g). Total nitrogen and phosphorus (ppm) shall also be monitored. Measurements should be taken using Hanna HI 9928 and HI 93703 water quality meters or other similar water quality meters.

• Frequency: Twice annually, spring and fall, outside bird nesting season.

• Desired Outcomes: Maintain healthy water quality to support salt marsh habitats.

• Triggers: Water quality monitoring shows consistent trends of decline, particularly reduced DO and/or increased turbidity, TSS, nitrogen and phospohorus.

If monitoring results indicate a decline in water quality, the manager will coordinate with the Corps to determine potential causes and adaptive management actions. Declines in water quality may be attributed to poor water circulation in the Marsh, which may indicate a need for more frequent or targeted water quality monitoring, inspection and repair of tide gate/culvert structures, culvert trash screens, and/or dredging maintenance. Declines may also be attributed to poor water quality in the Santa Ana River and/or local surface runoff and storm drains, which may indicate a need for additional monitoring and/or coordination with agencies managing such flows into the Marsh.

• Reporting: Monitoring results will be compiled in each year’s annual report along with a summary of any adaptive management actions taken and recommendations for future action or changes to the monitoring program. Data will be presented in tabular and graphic formats, indicating correlating rainfall and effluent discharge from upstream sources, as applicable.

2.3.2 *Topography Monitoring* The depth and extent of sediment deposits will be monitored in the tidal channels through topographic surveys. The manager will prepare cross-sectional channel topographic profiles and photo documentation at a minimum of twelve selected locations within the Marsh identified in Figure 9. Locations and numbers of cross-sections may be adjusted over time as trends in sedimentation become clear or to avoid impacts to cordgrass and resident rails. The timing of the surveys shall be approximately repeated, outside nesting season, to enable year-to-year comparisons.

The cross-section locations shall be repeated to enable year-to-year comparisons.

Topographic surveys will be performed by an independent third-party surveyor with at least five years of qualifying experience in topographic surveying and have a current California Land Surveyor’s license. All survey work will be in accordance with the following USACE Engineering Manual (EM) technical references: EM 1110-1-1002 (most recent edition) Survey Markers and Monumentation and EM 1110-1-1005 (most recent edition) Control and Topographic Surveying. Perform all surveys using the control network obtained from the USACE. The network uses coordinates from NAD83 California Lambert Zone 6, and elevations referred to Mean Lower Low Water (MLLW). The unit of measure will be U.S.

Survey Feet. All survey and mapping work must be in the datum, projection and units of the control provided by the USACE.

For each cross-section profile, the manager will install permanent transect endpoints on either side of the channel flush-mounted to the ground. Topographic cross-section data will be collected along the length of each cross-section at five-foot intervals, at a change/break in slope, or where an elevation change exceeds 0.5 foot.