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Arana Gulch Enhancement Plan  -   Creekside Restoration Project

Sediment Basin Clearing Project at Harbor High School
 
Informal Fish Survey

The Sediment Basin Clearing Project
at Harbor High School
Santa Cruz, CA.

Prepared by:
Roberta Haver, B.S.
Arana Gulch Watershed Alliance (AGWA) Coordinator

Prepared for:
Jess Mitchell, Game Warden,
California State Fish and Game

ln Compliance of Stream Alteration Agreement # 04 76-99

The first part of this report explains the background and benefits of the project. The second part presents the methodology of the project and the agreement of parties.

1. INTRODUCTION

Arana Gulch Watershed Alliance (AGWA) is a local group organized three years ago focusing on the management of resources in the Arana Gulch Watershed. This is a collaborative group dedicated to restoring, protecting, and enhancing fish and wildlife habitat, water quality, and natural resources throughout the watershed. Arana Gulch is a 3.5 square mile coastal watershed, and is a historic spawning stream for steelhead, with a substrate consisting primarily of Prisma sand. Sediment loading into the stream is a major problem. This is our first action project to address excessive sediments clogging the stream. Concurrently AGWA is in partnership with others at Harbor High School fish ladder to control bank erosion and improve fish and wildlife habitat.

BENEFITS

Benefits to the watershed which would result from clearing this sediment basin:

1. Immediate development of deeper pools downstream, as well as fewer of the large, soft bars, which inhibit adult upstream migration following the storms of the past several years.

2. Reduce bank erosion, since streams with partly-cohesive or non-cohesive banks become narrower and slightly deeper when coarse sediment transport is diminished.

3. Reduce sedimentation and the resulting excess oxygen demand in the tidal segments of the stream and the upper harbor.

4. Maintaining channel capacity not only through the high-school parcel, but also through the Jeffrey's reach and City's greenbelt parcel.

5. Speeding post-El-Nino recovery of all downstream channel segments from the sedimentation episode caused by 1998 storms, and enhancing steelhead passage by reducing the number and width of the sandy bars and shoals which inhibit steelhead migration.

6. Adding to stability of all reaches downstream from the basin, including the fish-ladder reach about to be restored, but also including the intervening ('tennis court') reach, the City's greenbelt parcel, and the tidal area just upstream of the harbor.

7. Reducing sedimentation of the harbor.

8. Reducing wear-and-tear and downtime due to flooding of the sewer lift station on the downstream side of Soquel Drive, resulting in lower costs and increased reliability, plus less likelihood of an uncontrolled overflow/upset.

The plan for clearing the sediment basin in compliance with Stream Alteration Agreement 0476-99 has four key players; Santa Cruz City Schools, Santa Cruz Port District, Coastal Watershed Council, and AGWA. All parties will continue involvement throughout the process.

• Santa Cruz Schools gives permission for work and will be assisting in the monitoring by photo documenting the before, during and after condition of the site and help with the watering regime. Their interest in the project is primary property protection and flood control.

• The Port District will facilitate the removal of the sediment. Removal of sediments before reaching the harbor is a direct benefit to the Port District Harbor operation.

• The Coastal Watershed Council (CWC) will assist in the turbidity monitoring before and after sediment removal and in the revegetation process and in monitoring. CWC is a local nonprofit dedicated to volunteer water monitoring and habitat protection and restoration.

• AGWA will orchestrate the removal of vegetation and planting of new vegetation. A representative member of AGWA will be in attendance during all four phases of the project: 1) vegetation removal, 2) sediment removal, 3) revegetation and 4) monitoring. AGWA continues to work on managing resources throughout the Arana Gulch Watershed.

The proposed methodology to perform the sediment removal from the basin and adherence to the Stream Alteration Permit is presented below followed by the Monitoring Plan:

II. Sediment Basin at Harbor High School Action Plan (see Table I)

Exotic Plant Removal and revegetation:

1. Thirteen alders within the basin and other trees within the actual confines of the basin walls will be removed. Twenty-foot lengths of the larger alders will be stockpiled along the southeastern edge to allow quick construction of a log structure to aid migration through the basin, if such proves needed.

2. Exotic vegetation will be removed including the two large acacias on the southeast bank. Revegetation of oaks, big leaf maples, and box elders since that grow well will improve habitat cover. The hope is the growth of equally large and vigorous trees immediately beyond the basin may be spurred by the removal of competition, such that a semi-closed canopy may develop, more amenable to occasional long term re-occupancy of the basin when necessary.

3. Trees within six feet upstream of the service road will be retained, which include several willows and alders that are 8-to 15-feet high. These will help shade the stream from the southwestern sun, screen the basin from the road, and provide both hydraulic roughness and cover under all seasonal conditions. Further they can lead to diverse and changing patterns of flow through the arch culvert beneath the access road, facilitating upstream migration of steelhead.

4. Vegetation and tree removal is scheduled for completion by August 30, 1999.

Sediment removal (see attachment A):

1. City and County Public Works Departments may contribute to the work as well as an outside contractor will perform mechanical removal of sediments in basin.

2. Mechanical sediment removal to be completed by October 15, 1999.

Turbidity:

1. Before and after turbidity collection before and after records by CWC.

2. Stream turbidity shall not exceed JTU's =50 NTU'S.

3. Results will be submitted to Fish and Game and kept at AGWA office.

Revegetation mitigation:

1. Up to 39 mix trees: alders, maples, box elders are to be planted in vicinity of sediment basin.

2. Sites will be prepared by October 1.

3. Best planting time is in October or after first winter rain.

4. New arboreal to be watered as needed (see monitoring plan, p.4).

Recommendations 1-9, 11, 16, 19-21 and 22:

1. All recommendations are to be adhered to.

2. Fish and Game will be notified by AGWA Coordinator of date of commencement of at least five days prior to completion. Fish and Game representative will be invited to inspect for compliance.

3. Work is to be completed by October 15, 1999.

Recognition Plaque:

1. Volunteer recognition plaque to be created and installed in area by AGWA.

2. Plaque acknowledges all participants in this project.

3. To be installed within six weeks of completion of planting.

Monitoring Plan

Photo Documentation:

1. Digital camera photo documentation by Santa Cruz Schools staff will be submitted to Fish and Game.

2. Photos are to be taken before work begins, during the removal process, after revegetation and on an annual basis for the next five years.

Revegetation Monitoring:

1. Alder cuttings from existing trees will be used for some of the replacement of cut alders, watering these cuttings is crucial to success of their rooting,

2. AGWA and CWC volunteers, students and parents will be watering and monitoring these plants for 5 years,

3. A 70-80% success is to be maintained. AGWA will replant if needed.

Review, monitoring and reapplication for next year:

1. AGWA members will evaluate the project during and after the winter storms,

2. Reapplication to Fish and Game for an annual maintenance program.