Hahamongna-Watershed-Park-Master-Plan.pdf

Hahamongna Watershed Park

Master Plan Adopted September 29, 2003

THE CITY OF PASADENA

HAHAMONGNA

WATERSHED PARK

MASTER PLAN

Adopted: September 29, 2003

The Arroyo Seco Master Plans consist of the following:

Hahamongna Watershed Park Master Plan Central Arroyo Master Plan Lower Arroyo Master Plan Rose Bowl Use Plan Arroyo Seco Design Guidelines

Workstation 03 Rectangle

Hahamongna Watershed Park During the winter months with storm water held

Behind Devil’s Gate Dam

CITY OF PASADENA / ARROYO SECO MASTER PLANS

Hahamongna Watershed Park Master Plan

HAHAMONGNA WATERSHED PARK MASTER PLAN

Hahamongna Watershed Park Advisory Committee

Tom Selinske, Chair Gregor Edwards Jody Gerstner Frank S. Osen Vannia de la Cuba Michael Hurley Elizabeth Pomeroy Joe Feinblatt Mildred Hawkins Bill Ukropina Anita Fromholz Pixie Boyden Maria Isenberger

Past Committee Members Denise Alvarado Pam Garcia Ramon Oceguera Roy Begley Greg Jones Tony Santilena Eugene Brooks Mark Nelson Tom Seifert, Former Chair Jarratt Brunson Omel Nieves Dr. Ron Williams Jeffery Commons Phil Novelly Katherine Luna Mary Freeman Henreen Nunley John Evans

City of Pasadena Department of Public Works Parks and Natural Resources Division Martin Pastucha, Director Robert C. Baderian, Past Assistant to the City Manager Julie Gutierrez, Past Director Kathy Woods, Parks and Natural Resources Administrator Rosa Laveaga, Arroyo Seco Park Supervisor, Project Manager John Cox, Assistant Project Manager

Pasadena Water & Power Phyllis Currie, General Manager Rufus Hightower, Past General Manager Brad Boman, Principal Civil Engineer Gary Takara, Civil Engineer

Raul Garibay, Civil Engineer

Master Plan Consultant Team Takata Associates, Landscape Architecture, Lead Consultant Philip Williams Associates, Hydrology & Geomorphology Hintz & Balvin, Community Outreach The Natelson Company, Inc., Finance Miralles Associates, Architecture Montgomery Watson, Civil & Environmental Engineering

Beth Thielen, Artist Parsons Engineering Sciences, Biology Hunt Design Associates, Graphic Design

Cover art by: rhandi

TABLE OF CONTENTS

Section Page

1.0 INTRODUCTION 1-1

1.1 Regional Context ………………………………………………………………………. 1-1

1.2 Relationship to the General Plan ………………………………………………………. 1-5

1.3 Project History …………………………………………………………………………. 1-5

1.4 Recent Planning ……………………………………………………………………….. 1-9

1.5 The Guiding Principles for the Arroyo Seco…………………………………………… 1-11

1.6 Goals & Objectives of the Hahamongna Watershed Park Master Plan………………… 1-12

1.7 Report Organization …………………………………………………………………… 1-16

2.0 EXISTING CONDITIONS, ISSUES & OPPORTUNITIES 2-1

2.1 Ownership, Easements & Jurisdiction ……………………………………………….. 2-2

2.2 Zoning & Land Use ………………………..………………………………………….. 2-6

2.3 Natural Environment ………………………………………………………………….. 2-6

2.4 Flood Management ……………………………..…………………………………….. 2-27

2.5 Sediment Delivery & Management …………….…………………………………….. 2-32

2.6 Water Conservation …………………………………………………………………….. 2-34

2.7 Utilities ……………………………………..………………………………………… 2-37

2.8 Circulation …………………………………………………………………………….. 2-48

2.9 Parking ………………………………………………………………………………... 2-54

2.10 Existing Recreation ……………………………..……………………………………… 2-56

2.11 Cultural & Archeaological Resources ………….……………………………………… 2-58

2.12 Summary of Community Outreach …………..……………………………………….. 2-61

2.13 Signage & Graphics ………………………..…………………………………………... 2-66

2.14 Issues & Opportunities …………………….…………………………………………… 2-68

3.0 HAHAMONGNA WATERSHED PARK MASTER PLAN 3-1

3.1 Water Resources Management ………………………………………………………... 3-1

3.2 Conceptual Grading Plan …………………………………………………………… . 3-11

3.3 Habitat Restoration …………………………………………………………………….. 3-16

3.4 Recreation Trails ………………………………………………………………………. 3-42

3.5 West Side & Oak Grove Area Improvements……………………………………………. 3-49

3.6 East Side Park Improvements …………………………………………………………… 3-55

3.7 Circulation & Parking …………………………………………………………………. 3-56

3.8 Utilities & Infrastructure ……………………………………………………………… 3-61

3.9 Safety, Security & Accessibility ……….………………………………………………. 3-68

3.10 Programs ………………………………………………………………………………… 3-70

4.0 IMPLEMENTATION OF THE MASTER PLAN 4-1

4.1 Implementation Plan …………………………………………………………………… 4-1

4.2 Water Resources Commission………………………………………………………….... 4-8

4.3 Environmental Requirements ………………………………………………………….... 4-8

APPENDIX A: Master Plan Concepts and Alternatives A-1

A.1 Master Plan Concepts …………………………………………………………………. A-1 A.2 Disc Golf Altenative …………………………………………………………………… A-4 A.3 Parking Structure Alternatives …………………………………………………………. A-6 A.4 Northern Bridge of Perimeter Trail Alternatives ………………………………………. A-6 A.5 Windsor/Ventura Entrance Alternatives………………………………………………… A-9 A.6 Berkshire Entrance Alternatives …..……………………………………………………. A-11 A.7 Dam Keeper’s Quarters… ………………………………………………………………. A-11

APPENDIX B: Biological Inventories B-1

B.1 Vascular Plants Observed at Hahamongna Watershed Park ………………………….. B-1 B.2 Terrestrial Vertebrate Animals of Hahamongna Watershed Park & Nearby Areas With Similar Habitats …………………………………………………... B-11 B.3 References ……………………………………………………………………………… B-23

APPENDIX C: Plant Community Palettes C-1

C.1 Coast Live Oak Woodland …………………………………………………………… C-1 C.2 Southern Willow Scrub ………………………………………………………………... C-2 C.3 Mule Fat Scrub ….……………………………………………………………………… C-3 C.4 Riversidean Alluvial Fan Sage Scrub ………………………………….……………… C-4 C.5 Coastal Sage & Chapparral Scrub ………….……………………………………………. C-5 C.6 Southern Sycamore Riparian Woodland ………………….……………………………. C-7

APPENDIX D: Water Data: Needs & Costs D-1

APPENDIX E: Master Plan Project Descriptions E-1

APPENDIX F: Technical Report on Athletic Fields F-1

Section 1. Introduction

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SECTION 1:

INTRODUCTION

1.1 REGIONAL CONTEXT

The Arroyo Seco is a major tributary of the Los Angeles River. It flows out of the San Gabriel Mountains in the northwest corner of the City of Pasadena, forming a physical link between the San Gabriel Mountains and the Los Angeles River. Much of Pasadena’s civic identity is linked to the Arroyo Seco. Numerous museums, cultural institutions, academic and research facilities, and historic sites are associated with the Arroyo Seco; and a series of regional and local parks still preserve its original natural beauty, providing the community with diverse recreational opportunities. See Exhibit 1-1, The Arroyo Seco Environment.

As the waters of the Arroyo Seco flow through the City of Pasadena, the streamcourse passes through three distinct geographical areas: Hahamongna Watershed Park (the southern portion of the upper Arroyo Seco), the Central Arroyo, and the Lower Arroyo. The City of Pasadena is currently developing Master Plans for each area of the Arroyo Seco that lies within the City limits. (See Exhibit 1-2, The Arroyo Seco in Pasadena.) The Pasadena City Council conceptually approved the Draft Lower Arroyo Master Plan (LAMP) in February of 1997.

LAMP covers the Arroyo Seco from the southern boundary of the City to the Colorado Street Bridge near the 134 Ventura Freeway. The Central Arroyo Master Plan (CAMP) area extends from the Colorado Street Bridge to the 210 Freeway, just south of the Devil’s Gate Dam. The planning process for the Central Arroyo started in 1999 and in January 2000 the Pasadena City Council conceptually approved CAMP. The Draft Hahamongna Watershed Park Master Plan was given conceptual approval in January 1999. The Arroyo Seco Master Plan is comprised of all three Master Plans, plus the Rose Bowl Operating Master Plan and the Arroyo Seco Design Guidelines.

Hahamongna Watershed Park (HWP) is located in Township 1 North, Range 12 West on the Pasadena, California 7.5′ USGS quadrangle map. HWP is bounded on the south by the Devil’s Gate Dam area and Oak Grove Drive. Oak Grove Drive and the Jet Propulsion Laboratory (JPL) of the California Institute of Technology bound HWP to the west in the City of La Cañada-Flintridge. To the east, HWP is bounded by the residential neighborhoods of Pasadena and Altadena. The study area extends as far north as the JPL Bridge, which connects the east parking lot to the main JPL campus on the west. See Exhibit 1-3, Study Area.

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Exhibit 1-1, The Arroyo Seco Environment Source: NorthEast Trees

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Exhibit 1-2, The Arroyo Seco in Pasadena

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In 1920, the Devil’s Gate Dam was constructed at the narrowest section of the Arroyo Seco for flood protection and as a water reservoir to recharge the Raymond Basin Aquifer.

Hahamongna Watershed Park (HWP) is approximately 1,300 acres of open space extending up the Arroyo Seco Canyon from the Devil’s Gate Dam. The lower watershed, the 300 acres roughly defined as the flood plain and basin behind the dam, is the focus of this Master Plan.

1.2 RELATIONSHIP TO THE GENERAL PLAN

This Master Plan has been completed in response to the policies and principles set forth in the City of Pasadena’s Comprehensive General Plan. The seven guiding principles of the General Plan are as follows:

1. Growth will be targeted to serve community needs and enhance the quality of life.

2. Change will be harmonized to preserve Pasadena’s historic character and environment.

3. Economic vitality will be promoted to provide jobs, services, revenues, and opportunities.

4. Pasadena will be promoted as a healthy family community.

5. Pasadena will be a city where people can circulate without cars.

6. Pasadena will be promoted as a cultural, scientific, corporate, entertainment, and educational center for the region.

7. Community participation will be a permanent part of achieving a greater city.

Pursuant to the second Guiding Principle, Objective 9, Open Space Preservation and Acquisition specifically identifies the Arroyo Seco for preservation. Policy 9.2 states “continue and complete comprehensive planning for, and implementation of, plans for the Arroyo, including restoration of the natural area of the Lower Arroyo and the development of the Hahamongna Watershed Park Plan.” This Master Plan directly complies with these mandates.

1.3 PROJECT HISTORY

The Hahamongna Watershed Park Master Plan (Master Plan) report is a product of an analysis of existing conditions, a review of pertinent documents, and input from a wide variety of stakeholders and from the community through an extensive outreach program.

Additional input was received from City officials and staff. Oversight of the entire project

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The following summarizes the history of the area and the project.

May 1919 The area north of what was commonly known as Devil’s Gate (and today encompasses the entire study area) was annexed to the City of Pasadena by popular vote. This area was referred to as the “Arroyo Addition.”

The City of Pasadena entered into a lease agreement with the City of Los Angeles for the construction of Devil’s Gate Dam as well as for the maintenance of a reservoir capable of impounding waters of the Arroyo Seco for the purposes of water conservation and flood control.

1920 The County of Los Angeles completed construction of Devil’s Gate Dam at the narrowest portion of the Arroyo Seco for flood control and water conservation.

Jan. 1931 “Arroyo Addition No. 2”, consisting of approximately 1,000 acres in the upper

Arroyo Seco watershed was annexed to the City. Now known simply as the Upper Watershed area, it extends north from the JPL Bridge.

1948 The Los Angeles County Department of Public Works (LACDPW) constructs

13.1 acres of spreading grounds and a two-acre overflow basin (No.13) on the northeast edge of the flood basin.

1960 On the eastside of the basin, 9.6 acres were leased to the Jet Propulsion

Laboratory (JPL) for parking. This resulted in an asphalt lot with 1,132 parking spaces.

1968 The City of Pasadena leased the operation and maintenance of Oak Grove Park to the County of Los Angeles.

Jul. 1970 Approximately 30 acres (on the northwest side of the study area, most within the

Los Angeles County easement and a portion of Oak Grove Park) was sold to the Metropolitan Water District (MWD).

1971 The County designed and implemented major improvements to Oak Grove Park including roadways, restrooms, maintenance facilities, and other infrastructure.

1978 The Division of Safe Operation of Dams (DSOD) imposed an operational restriction on Devil’s Gate Dam and officially declared the dam seismically unsafe. These actions were taken in part due to the 1971 Sylmar earthquake.

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May 1986 The City of Pasadena received a grant from the Santa Monica Mountains Conservancy for a study of the use of the Devil’s Gate basin. A formal progress report for the Devil’s Gate Multi-Use Project (DGMUP) was presented to the Pasadena City Council in March of 1988.

Jan. 1987 The Devil’s Gate Multi-Use Project Advisory Committee was established to further develop and design this plan. Preliminary economic, biological, and feasibility studies were conducted by outside consultants. The Devil’s Gate Project was propelled by Pasadena’s Strategic Planning Process, a citizen’s planning project, which identified it as one the most promising projects necessary to make Pasadena a great city in the year 2000 and beyond.

Mar. 1987 On the west side of the basin, 1.21 acres were leased to JPL for parking. This resulted in an asphalt lot with 214 spaces.

1986-91 A series of public participation workshops were held which included exhibits by environmental artists Newton & Helen Harrison.

The Devil’s Gate Joint Power Planning Authority, made up of appointees representing Pasadena, La Cañada-Flintridge, Native Americans, and the Santa Monica Mountains Conservancy held a series of public meetings during an 18-month period. It also oversaw the development of the Preliminary Plan by Takata Associates, held three public workshops as part of the planning process, developed governance and funding recommendations, and obtained $1.86 million in County Parks bond money through the November 1992 election.

Dec. 1992 The Preliminary Park Plan was received and conceptually approved by the

Pasadena City Council.

1993 The area was named Hahamongna Watershed Park

Oct. 1993 The Pasadena City Council established a Creation Task Force to develop the legal structure for the Hahamongna Operating Company (HOC) which would implement, manage, and operate the project. When the transfer of the operation and maintenance responsibility of the Oak Grove Park portion was returned to the City of Pasadena, 500 people attended the dedication of Hahamongna Watershed Park.

The HOC began monthly meetings starting in November of 1994. These meetings were open to the community. A 300-person mailing list was developed for meeting and event notification. During its operation, HOC participated in

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Dec. 1994 All mining operations in the Hahamongna Watershed Park basin ceased.

As many as eight mining operations had been in the basin and had been licensed to mine sand and gravel. They had contributed significantly to the dumping of concrete, asphalt, and other materials in the basin.

Nov. 1995 The rehabilitation of Devil’s Gate Dam was initiated by the County of

Los Angeles. HOC staff worked closely with the County and the contractor to minimize neighborhood impacts and begin habitat restoration in the flood basin. This project was completed in January of 1998.

Jan. 1996 Los Angeles County Department of Public Works (LACDPW) began the seismic strengthening and spillway modification to Devil’s Gate Dam. This project was completed in the winter of 1998.

Aug. 1996 The Pasadena City Council disbanded the Hahamongna Operating Company

Board and transferred all responsibilities of the Hahamongna Watershed Park to the Department of Public Works.

Nov. 1996 Hahamongna Watershed Park was allocated $1 million for capital improvements as a result of the 1996 Los Angeles County Park Bond Act.

Jan. 1997 The Pasadena City Council established the Hahamongna Watershed Park

Advisory Committee (HWPAC) which was comprised of all members of the City’s Recreation and Parks Commission with two additional members representing the Northwest Commission and two members representing the Utility Advisory Commission.

In September and October, two public hearings on Hahamongna Watershed

Park planning were hosted by the HWPAC to reaffirm the Preliminary Park Plan that had been completed nearly five years previous. More than 100 people representing community members, special interest groups, and regulatory agencies attended these meetings. From these meetings the “Park Elements” for HWP were established as the new framework for the final Master Plan.

Dec. 1997 The “Park Elements” that reflected consensus towards the development of the

Park’s Master Plan were presented to the City Council for review.

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Nov. 1998 The City Council reaffirmed its commitment to reinvestment and acquisition of parkland. The landscape architecture firm of Takata Associates was brought on board to develop the final Master Plan for Hahamongna Watershed Park.

Dec. 1998 The Pasadena City Council, with the recommendation of the Recreation and

Parks Commission, approved a motion to pursue the re-purchase of the 30-acre MWD property.

1999 Responsibility for operating and maintaining the 13.1 acres of spreading grounds on the northeast edge of the flood basin was turned over to the City of Pasadena.

The City Council authorized the use of the JPL parking lot lease funds for the planning, maintenance, and operation (including security) of Hahamongna Watershed Park.

1.4 RECENT PLANNING

In January of 1997, Pasadena City Council established the Hahamongna Watershed Park Advisory Committee (HWPAC) which was given the charge of overseeing the Master Plan process. Since a number of years had passed since the approval of the Preliminary Park Plan by City Council in December 1992, and the start of the Devil’s Gate Dam renovation in 1996, the HWPAC held two community workshops to solicit input on the project. Based on this public input, a list of Park Elements was drafted and adopted by the HWPAC in 1997 as a bridge between the Preliminary Park Plan and the start of the Final Park Master Plan Process.

The final Master Plan reflects these elements as they have evolved.

PARK ELEMENTS of 1997

Major Themes HWP should be a showcase for:

Water and natural resources education and utilization The preservation of native plants and habitat Native American culture Passive and active recreation

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Water Feature Water and water resources are major functions of this area that must be protected and enhanced.

An analysis of flood potential and sediment buildup in the basin should be pursued.

Now that Devil’s Gate Dam has been rehabilitated, Pasadena should coordinate with

Los Angeles County on the possible development of a water feature to maximize water conservation and habitat restoration in HWP.

Recreation Design children’s play features to emphasize appreciation of the natural environment.

Provide the opportunity to experience the natural outdoors by providing overnight camping, fishing, and nature study.

West Athletic Field—upgrade this field in cooperation with youth sports leagues to promote usage.

Johnson Field—integrate this venue into HWP by coordinating use and scheduling

Entrances Create an entrance at Woodbury & Arroyo/Windsor with access to the dam.

Create secondary entrances at Foothill Boulevard and Windsor/Ventura.

Prohibit any entrance at La Cañada-Verdugo Road or through residential neighborhoods.

Parking Renegotiate the leases for the Jet Propulsion Lab parking lots.

Ensure adequate parking at multiple sites around the park and at the central parking area on the west-side Oak Grove area.

Improve the parking area and intersection at Windsor/Ventura to promote safety and neighborhood protection.

Structures:

Minimize new structures and analyze costs and benefits related to maintenance and public safety.

All facilities should emphasize the natural setting and use of natural materials.

Trails & Linkages:

Develop a major perimeter trail around the Hahamongna basin for walkers and joggers.

Improve equestrian trails through the park and linkages to nearby trails. Provide a linkage for bicyclists outside of the basin to connect to the San Gabriel Mountain trails.

Trails should be inclusive where possible; multiple uses can coexist.

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Signage & Nomenclature:

Tasteful signage should be used for interpretive and educational purposes rather than facilities that are expensive to build and maintain.

Develop a standard nomenclature for all park signs.

Design Standards for Entire Arroyo:

Consistent design standards for all Arroyo parks and nature areas should be developed that would cover entrances, signage, circulation, architecture, native landscaping, and the use of Arroyo materials and crafts (such as rockwork and tiles) to convey the unique character and beauty of the Arroyo Seco.

1.5 THE GUIDING PRINCIPLES FOR THE ARROYO SECO

The Guiding Principles for the Arroyo Seco were developed to serve as the umbrella under which fall the specific goals and objectives for each of the Arroyo Seco Master Plans. These six Guiding Principles were developed collaboratively between members of the community, members of the Recreation and Parks Commission members of the Hahamongna Watershed Park Advisory Committee, and City staff. These Guiding Principles will also serve as a bridge between the Arroyo Seco Master Plans and the City's General Plan Update. The six principles are:

To encourage and promote the stewardship and enjoyment of the Arroyo Seco in

Pasadena.

To balance and integrate the interrelated issues of water resources, recreation, natural resource preservation and restoration, and flood management in the Arroyo Seco.

To provide a safe, secure and accessible Arroyo Seco for public enjoyment.

To recognize the importance to Pasadena of the history, cultural resources and unique character of the Arroyo Seco, and to conserve and enhance these assets.

To preserve and acquire open space in or adjacent to the Arroyo Seco.

To recognize that the Arroyo Seco in Pasadena is comprised of distinct geographical areas that are interconnected by a number of resources and features including, but not limited to, water, habitat, geology, recreation, and culture; and that it is part of a larger watershed.

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1.6 GOALS & OBJECTIVES OF THE HAHAMONGA WATERSHED

PARK MASTER PLAN

The following are the goals and objectives specific to Hahamongna Watershed Park:

Goal 1: Preserve, restore, and enhance the native habitats

Objectives:

• Develop a habitat restoration plan for Hahamongna Watershed Park.

• Protect and enhance the Hahamongna Watershed Park wildlife corridor linkages to the upper watershed and the downstream reaches of the Arroyo Seco.

• Restore, enhance, and reestablish the historical native plant communities of the Arroyo Seco.

• Create wetland and aquatic habitats in HWP to increase the biodiversity.

• Locate new facilities in developed or disturbed areas so as to minimize impact to established habitats.

• Enhance the edges of the spreading basins with native trees and other appropriate plantings to blend these facilities with the riparian setting.

• Limit exterior lighting for security, safety, and operational purposes to lessen the impact on nocturnal wildlife.

• Relocate existing overhead power and communications lines to restore the natural environment and provide adequate, safe maintenance access.

• Develop dam maintenance and flood control procedures that promote preservation of native habitats.

• Repair the harmful impacts of the mining operations by regrading the highly disturbed, unnatural topography within the flood plain to allow for the successful planting of native plant communities to establish quality habitat.

• Establish a monitoring program to study runoff and sediment delivery in the flood basin to determine impacts on plant communities in HWP.

• Restore areas where erosion has occurred.

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Goal 2: The Devil’s Gate flood control basin will be managed to provide protection to the developed and natural downstream areas.

Objectives:

• Facilitate the dam and reservoir maintenance operations in a manner that is compatible with the proposed features of the Master Plan and will result in minimal impacts to the surrounding area.

• Maintain or improve the flood capacity behind Devil’s Gate Dam.

• Develop a sediment removal plan that minimizes the impact to the basin and to the surrounding neighborhoods.

• Develop a grading plan that allows habitat restoration and recreational activities to co-exist with flood management and water conservation.

• Develop a multi-agency task force to review maintenance, sediment removal, dam operation, permit, and liability issues on a continual basis after this plan is adopted.

• Develop dam maintenance and flood control procedures that promote water conservation.

• Establish a monitoring program to study runoff and sediment delivery in the flood basin to determine impacts on flood management/water conservation capabilities.

Goal 3: Conserve and protect the water resources of the Arroyo Seco.

Objectives:

• Maximize groundwater recharge to minimize the amount of water purchased from outside sources.

• Develop a grading plan that allows habitat restoration and recreational activities to coexist with flood management and water conservation.

• Monitor water entering the basin from Flint Wash and various storm drains to ensure safe water quality.

• Develop a program to minimize and provide the means to control the inflow of trash from

Flint Wash and various storm drains.

• Develop an alternative to the JPL eastside surface parking area for expanded spreading basins for groundwater recharge.

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Goal 4: Provide diverse recreation opportunities for the Pasadena community.

Objectives:

• Balance the recreation needs for active, passive, and educational activities in HWP.

• Develop a grading plan that allows habitat restoration and recreational activities to co-exist with flood management and water conservation.

• Design children’s play areas to emphasize learning and connections to the natural environment.

• Distribute recreation facilities to allow equal access from the surrounding neighborhoods.

• Maintain the historic recreational uses within HWP.

Goal 5: Enrich and promote the unique history and culture of Hahamongna Watershed Park.

Objectives:

• Develop HWP as a “living laboratory” for local schools and environmental education programs.

• Preserve and encourage Native American use of HWP as a cultural resource.

• Explore the possibilities of a joint partnership with the U.S. Forest Service and Native Americans in developing an interpretive center and native-plant nursery at HWP.

• Develop design guidelines to ensure aesthetic compatibility and quality construction for any improvements made in HWP.

• Develop passive viewing areas with unique vantage points.

• Create programs that inform and educate the public about the natural processes, the history and the culture of the site.

• Underground or relocate the existing above-ground electrical transmission lines.

Goal 6: Provide a safe and secure park.

• Provide adequate water and sewage infrastructure where needed throughout HWP.

• Develop guidelines and delegate agency responsibilities for recreation, flood management, and water conservation liabilities.

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• Retain and enhance, as needed, the recently reestablished Park Ranger Program to ensure compliance with municipal laws, codes, and regulations. Secure entrances and perimeter of HWP.

• Develop an all-weather perimeter trail/road for emergency and maintenance access as well as for passive recreation.

Goal 7: Provide adequate circulation, access and parking

• Provide public transportation and nonmotorized access to HWP.

• Provide adequate parking throughout the park for all proposed recreation activities and facilities.

• Maintain and restore the trail links to the Central Arroyo, the surrounding neighborhoods, and the Angeles National Forest.

• Develop separate trail systems for bicycles, hikers, and equestrians wherever possible.

• Comply with ADA (Americans with Disabilities Act) standards for a “natural park.”

• Develop a signage system that provides clear directional information and informs park visitors without being intrusive.

• Improve the east entrance for better access, circulation, and traffic safety.

• Protect residential neighborhoods from the nuisances related to maintenance equipment, traffic, and noise.

• Improve and enhance regional trail connections.

• Continue to assist JPL in meeting its parking needs.

The Arroyo Seco Master Plans were developed by the combined efforts of the Planning and Development Department and the Department of Public Works. The implementing department for the completed Arroyo Seco Master Plans will be the Department of Public Works. The projects identified in the Arroyo Seco Master Plans are described and listed to easily translate to the City’s capital improvement program.

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1.7 REPORT ORGANIZATION

The HWP Master Plan report is the product of an analysis of existing conditions: A review of previous planning documents; meetings with user groups, neighborhood groups, regulatory agencies, environmental groups and other interested groups; three community workshops;

and the guidance and direction given by the Hahamongna Watershed Park Advisory Committee.

The Hahamongna Watershed Park Master Plan report consists of four sections:

Section 1 - Introduction: This first section provides an overview of the Arroyo Seco and Hahamongna Watershed Park; regional context; history; recent planning efforts; goals and objectives; and scope and content of the Master Plan report.

Section 2 - Existing Conditions, Issues, and Opportunities: This section identifies HWP's existing natural and man-made setting. A summary of the park's issues and opportunities, based upon the technical analysis and community outreach, are discussed.

Section 3 - Master Plan: This section describes the recommended Master Plan elements.

Section 4 - Implementation: This section details the phasing of specific Master Plan projects and provides a summary of environmental requirements needed to implement the Master Plan.

Secttion 2. Existing Conditions Issues & Opportunities

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SECTION 2:

EXISTING CONDITIONS,

ISSUES & OPPORTUNITIES

This section of the Master Plan describes the current physical setting of Hahamongna Watershed Park (HWP) and its environment. Opportunities for improvement and issues that pertain to the various features of the park are reviewed.

Hahamongna Watershed Park in 1988. Sediment removal and mining operations are evident throughout the flood basin.

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2.1 OWNERSHIP, EASEMENTS & JURISDICTION

LAND OWNERSHIP

Hahamongna Watershed Park (HWP) is located within the City of Pasadena. Other neighboring landowners within the basin include the Metropolitan Water District (MWD) and the Jet Propulsion Laboratory (JPL). The MWD property is within the master plan study area and although JPL is not a part of this park master plan, it is very much within the sphere of influence of HWP. The majority of the JPL campus is located in the City of La Cañada-Flintridge, northwest of HWP. Refer to Exhibit 2-1, Master Plan Area, for the major physical elements located within the study area.

JPL leases the two parking lots within HWP. The 30-acre MWD property was parkland purchased from the City of Pasadena in 1968. The current leaseholders on MWD property include the United States Forest Service (USFS), Los Angeles County Fire Camp 2, and the Rose Bowl Riders who sublet to the Tom Sawyer Camp. The study area also includes a small parcelof land between the mouth of Flint Wash and the dam, including an area southeast of the intersection of Linda Vista Avenue and Oak Grove Drive, which is currently within the La Cañada-Flintridge city limits (Exhibit 1-3, Study Area).

EASEMENTS

Los Angeles County Flood Control Easement

Los Angeles County Department of Public Works (LACDPW) holds an easement granting the County the right to construct and maintain Devil’s Gate Dam, its spillway, bypasses, tunnels and other support facilities as may be necessary or convenient for the construction and maintenance of a reservoir capable of impounding the waters of the Arroyo Seco for purposes of storage and control; and to control such waters as may be necessary in the prevention of damage by flood. The easement applies to land below the 1075′ contour as determined from the benches of the United States Geological Survey (USGS) See Exhibit 2- 5, Water Elevations later in this section.

Included in this granted easement, the City retained the right to the top of the dam as a public access way and utility corridor across the Arroyo Seco.

Gabrielino Trail Easement

The U.S. Department of Agriculture / U.S. Forest Service (USFS) has been granted an easement by the City of Pasadena for the Gabrielino Trail. The Gabrielino Trail begins at the intersection of Windsor Avenue and Ventura Street and extends north for 1.5 miles into the

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Arroyo Seco Canyon and then enters USFS lands in the Angeles National Forest. Two-thirds of a mile is within the HWP study area. This section of the trail from its beginning at the intersection of Windsor and Ventura, is a multi-use, paved trail and a maintenance/ emergency roadway that follows the upper edge of the eastern slope of the basin. Bicyclists, hikers, and equestrians are all allowed access along the trail.

Utility Easements

Southern California Edison and the Southern California Gas Company hold easements for their utility lines. See Section 2.6, Utilities, for further information on these lines. The Pasadena Department of Water and Power holds easements for utility lines within the MWD property.

JURISDICTIONS

U.S. Army Corps of Engineers

The U. S. Army Corps of Engineers has jurisdiction over the area of potentially impounded waters north of the dam (below the 1040.5 elevation). North of this area and above the

1040.5 elevation, the Corps’ jurisdictional area includes the intermittent, meandering stream corridors at their high-water mark. Any impact to these areas will require the filing of an Army Corps of Engineers 404 Permit (See Environmental Requirements Technical Report).

California Department of Fish and Game (CDF&G)

The CDF&G has jurisdiction over the entire Master Plan area:

Should any project within the HWP Master Plan area change the natural flow or bed, channel or bank of any river stream or lake, a Section 1601/1603 Stream Alteration Agreement will be required. This same area of jurisdiction is shared with the Army Corps of Engineers.

Should any project within the HWP Master Plan area impact any state-listed or endangered species or their habitat, then an MOU (Memorandum of Understanding) under the California Endangered Species Act will be required. Again, this jurisdiction is over the entire Master Plan area.

U.S. Fish and Wildlife Service (USFWS)

If federally listed sensitive species were to be found in areas of the park that are to be disturbed, Federal Endangered Species Act (FESA) Section 7 or 10 consultations with the USFWS could be required.

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Following the City Council's conceptual approval of the draft Hahamongna Watershed Park Master Plan, USFWS declared approximately half of HWP critical habitat for the Southwestern Arroyo Toad, a federally listed endangered species. On February 7, 2001, approximately 182,000 acres in California were designated critical habitat for the Arroyo Toad pursuant to the Endangered Species Act of 1973, as amended. The federal ruling designated six miles in Arroyo Seco Creek, from the Long Canyon confluence downstream to the central area of the Hahamongna Basin, as Arroyo Toad critical habitat area. On October 30, 2002, the U.S. District Court for the District of Columbia eliminated the current designation of critical habitats for the Arroyo Toad. The Building Industry Legal Defense Foundation sued the U.S. Interior Department to nullify the habitat designation. Under federal law, the costs to industry and the public of designating critical habitat for an endangered species must be considered, and if they outweigh the benefit to the species, then habitat need not be designated. The U.S. Fish and Wildlife Service (USFWS) has until July 30, 2004, to redo its economic impact analysis and the Interior Department will decide by 2005 which areas of critical habitat to re-designate. See Exhibit 2-3, Terrestrial Natural Plant Communities, for the limits of the critical habitat area and Section 3 for more detailed information on this topic.

Critical habitat identifies specific areas that are essential to the conservation of a listed species with respect to areas within the geographic range occupied by the species. The City of Pasadena completed focused biological protocol surveys of the Southwestern Arroyo Toad in December 2001, and the presence of the Southwestern Arroyo Toad was not indicated.

(See Focused Herpetological Surveys Conducted in Support of the Arroyo Seco Master Plan by AMEC, December 2001.) A minimum of three consecutive years surveying for the Arroyo Toad is needed to establish their presence. Due to the extreme drought in the winter of 2002, the USFWS advised the City to not complete a survey started in 2002, but instead extend the surveys through 2004.

California Regional Water Quality Control Board (CRWQCB)

Elements of the Park Master Plan may require a Section 401 Water Quality certification under the Clean Water Act if any project results in a discharge into a water body. The CRWQCB also has jurisdiction over the area for any construction project with grading of more than five acres; in this instance a National Pollution Discharge Elimination System (NPDES) program is required.

Either the County of Los Angeles and/or the City of Pasadena will review any alterations to storm drains, septic systems, sewer connections, power, communications systems, or fire suppression requirements.

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2.2 ZONING & LAND USE

ZONING

Hahamongna Watershed Park is zoned as open space with the exception of a parcel zoned as Planned Development Districts (PD-16). This parcel, indicated in Exhibit 2-2, Zoning, is leased to JPL for its east parking area.

The adjacent land in Pasadena, Altadena, and La Cañada-Flintridge is zoned residential. All Pasadena areas are zoned RS-4, which permits four residential dwelling units per acre. The JPL parking lots are allowed under a conditional-use permit.

LAND USE

The entire basin is designated open space by the City of Pasadena’s General Plan. “Open Space” is defined by the Pasadena General Plan as follows: “This category is for a variety of active and passive public recreational facilities and for City-owned open space facilities. This includes natural open spaces and areas which have been designated as environmentally and ecologically significant. This category also applies to land which is publicly owned, though in some instances public access may be restricted. Most importantly, this designation only applies to lands owned by the City.”

Within the LACDPW Flood Control Easement, Oak Grove was given the designation of parkland. This area was City-dedicated parkland at the time Los Angeles County assumed control of it; and this designation remains. Permitted uses of City-dedicated parkland include active and passive recreation. Under this permit the County first developed the recreation facilities at Oak Grove. Exhibit 2-2, Zoning, illustrates dedicated parkland and waterfund land. Waterfund land is City land maintained and used by the Pasadena Department of Water and Power for water conservation purposes.

2.3 THE NATURAL ENVIRONMENT

Hahamongna Watershed Park (HWP) is located on the south flank or south-facing slopes of the San Gabriel Mountains, in the Arroyo Seco drainage. The San Gabriel Mountains are part of the Transverse Ranges physiographic province of southern California. HWP is situated in what was formerly the Arroyo Seco Canyon. After the dam was constructed, sediments from mountain runoff began to accumulate behind it. This deposition raised the ground surface in the reservoir area and created a broad plain between the canyon walls. Today, this flood sediment plain gently slopes from an upstream elevation of approximately 1100 at the JPL Bridge to a downstream elevation of approximately 986 at the dam face. The former canyon walls slope steeply up from the sediment plain at its edges.

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The sediment plain itself is quite irregular due to erosion and historical excavation within the reservoir. Throughout the park, shallow ridgecrests, alluvial fan slopes, and riparian areas exist along the floor of the Arroyo Seco drainage. There are a few areas that are level, or have nearly level, terrain.

HWP is located approximately at the boundary between two different precipitation regions— The San Gabriel Mountains and the San Gabriel Valley. These two regions receive an average of 27.5" and 17.6" of rain per year, respectively. Most precipitation occurs during the winter months.

The upper reaches of the Arroyo Seco watershed cover an area of approximately 21.75 square miles and include runoff from Ladybug, Cloudburst, Daisy, Cloby, Little Bear, Bear, Long, Dark, Twin, Brown, Pine, Falls, Aqua, Fern, El Prieto, and Millard Canyons. Between the JPL Bridge and Devil’s Gate Dam an additional 10.15 square miles drains directly into the basin primarily through municipal storm water culverts, but also through Flint Wash which drains into the southwest corner of the basin from the City of La Cañada-Flintridge.

Three large drainages within and near HWP contain ephemeral or intermittent streams with surface water flow only during extended periods of sustained rain and runoff. Streams within these three drainages originate from the upper elevations of the Arroyo Seco, Millard Canyon, and El Prieto Canyon. All streams provide at least minimal surface flow to the JPL Bridge for a portion of their length throughout the year.

THE ALLUVIAL FAN ENVIRONMENT

Erosion from the steep slopes of the San Gabriel Mountains is commonly deposited where there is a sudden reduction in streambed slope. There, the deposits form a roughly semi-circular arc referred to as an alluvial fan. HWP is situated at the opening of the Arroyo Seco canyon along the upper portion of an alluvial fan environment.

Alluvial fans are complex and potentially unstable environments, since they occur at the point between sediment supply and the beginning of extensive channel carving. Processes that have caused extensive damage on alluvial fans include lateral scour in existing channels, the formation of new channels by sudden redirection of flow at the top of the alluvial fan, and inundation by debris and sediment in the alluvial fan environment. These types of channel processes are common.

THE BIOLOGICAL ENVIRONMENT

The plant communities, vegetation, and wildlife of HWP probably would not exist in their current array without man’s influence. The altered and unnatural environmental conditions currently found there are due mainly to four factors. These are: (1) the presence of Devil’s Gate Dam; (2) the requirements for necessary sediment and debris removal behind the dam;

(3) the landscaping practices that have over time significantly changed the appearance and composition of HWP and nearby areas, including the MWD property, from that once familiar to the Native American Gabrielinos; and (4) the encroachment of invasive nonnative plants.

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Field inventory surveys of biological resources in HWP and the MWD property were conducted over a twelve-month period. Both vegetation and wildlife resources were surveyed in a floristic and faunistic manner that ensured a complete and thorough identification of all species encountered during the fieldwork. The inventories also included the identification of existing natural plant communities, and landscaped and ruderal (non-native) vegetation in the park. The inventory information about biological resources in HWP helped to define the existing setting and to lay the foundation for the habitat establishment and restoration plan presented in Section 3 of this Master Plan.

More than 300 plant species and nearly 100 animal species were observed during the inventory surveys. These numbers demonstrate a high biodiversity in HWP. See Appendix B.1 & B.2 for an inventory of existing plants and animals observed. Only plants that were actually observed were placed on the plant species inventory list. However, the animal species inventory list includes both recently observed and historical records of animals known from HWP and nearby areas with similar habitats.

The vegetation classification of plant communities in the study area was taken mainly from Holland (1986) and Sawyer and Keeler-Wolf (1995).1 Plant nomenclature followed that of Hickman (1993), Munz (1959, 1968, and 1974), Sunset (1995), and Bailey (1949). Animal species nomenclature followed that of Jameson and Peters (1968), Burt and Grossenheider (1980), Whitaker (1980), and Ingles (1995) for mammals; Peterson (1990) National Geographic Society (1983), Stokes and Stokes (1996), Udvardy (1988), and Garrett and Dunn (1981) for birds; and Stebbins (1985), and Behler and King (1979) for reptiles.

The Existing Setting

HWP, as it exists today, represents a unique albeit somewhat unnaturally occurring set of plant and animal communities that largely would not be present in their current assemblage without Devil's Gate Dam. However, a mixture of California terrestrial natural plant communities (Holland, 1986), or vegetation series (Sawyer and Keeler-Wolf, 1995), continues to dominate the site.

Throughout the majority of the Arroyo Seco drainage in HWP, riparian scrub habitats and weedy nonnative grassland dominate the floor of the central portion of the drainage,and a portion of the MWD property. Oak woodland and other types of scrub habitats occupy large and small variable areas along the perimeter and/or side walls of the drainage. Segments of the survey sites (i.e., landscaped areas) are widely populated with introduced ornamental shrubs and trees, and exotic, ruderal weedy species of grasses and forbs (herbaceous, non-grass species). Several of these introduced species are from places other than California, and some of the plants are native to other regions and habitats of California but not to those in which HWP is located. Many of the introduced plant species generally used in landscaped settings are not from North America.

1 See Appendix B.3 for a complete reference list of sources cited in this portion of the Master Plan.

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Several terrestrial natural plant communities, that form a patchy mosaic of dominant vegetation types, occupy the survey areas. A particular plant community may fill an area forming relatively pure stands of the dominant species, or the site may contain transitional areas that possess elements of several plant communities, or vegetation series and associations, as the case may be.

The Plant Communities

At least six native terrestrial natural plant communities exist in the survey areas with characteristics common to (1) coast live oak woodland, (2) southern willow scrub, (3) mule fat scrub, (4) riversidian alluvial fan sage scrub, (5) sage scrub, and (6) southern sycamore riparian woodland. Holland (1986) describes these communities in a document prepared for the California Native Diversity Database. See Exhibit 2-3, Terrestrial Natural Plant Communities.

One nonnative, terrestrial natural plant community is also present in large and small sections of the master plan study area survey sites, i.e., ruderal vegetation. In areas of the basin that have undergone considerable disturbance by man due to periodic flood management through sediment and debris removal upstream of Devil’s Gate Dam, much of the vegetation is comprised of ruderal species. The majority of this ruderal vegetation is comprised of herbaceous forbs rather than nonnative grasses. However, certain small areas are dominated by introduced, nonnative grasses and fewer forbs. Holland (1986) refers to this community as nonnative grassland. Nonnative grassland is widely scattered depending on the history of site disturbance by man (e.g., repeated fires and grading).

It should be noted that a vegetation category termed “streambed riparian vegetation” is also described below. However, this is not a true terrestrial natural plant community or vegetation series. This vegetation category is used in this report to help depict those locales along the Arroyo Seco stream channel where riparian or wetland indicator species may occur in isolated areas and/or numbers of individual species. These sections of the stream channel are sparsely covered with vegetation since it is still in a state of primary succession due to ongoing disturbance by annual flooding and scouring from seasonal rainfall runoff and sediment deposition. These species may be present in greater numbers and distribution in other major terrestrial natural communities of HWP.

Under a more recent classification system of vegetation by Sawyer and Keeler-Wolf (1995), the terrestrial natural plant communities in HWP are more complex. Using Sawyer and Keeler-Wolf’s approach, at least twelve different vegetation series are known from the surveyed areas of the Arroyo Seco and canyon slopes and sidewalls along the site boundaries. The vegetation that dominates the HWP survey sites include the following

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Sawyer and Keeler-Wolf series: Coast live oak, arroyo willow, black willow, red willow, mule fat, scalebroom, California sagebrush-California buckwheat, California sagebrush-black sage, chamise-black sage, sumac, California sycamore series, and California annual grassland.

Descriptions of the terrestrial natural plant communities (Holland, 1986) and/or the related vegetation series (Sawyer and Keeler-Wolf, 1995) are given below. For ease of reading this report, information about a particular vegetation series is combined with that for the respective terrestrial natural community.

Coast Live Oak Woodland

Coast live oak woodland is typically located on north-facing slopes and shaded ravines in southern California.