Supplemental Carmel River Watershed Action Plan

106 Pages·2007·11.33 MB·English

March 2007
Supplemental Carmel River
Watershed Action Plan
Prepared for
The Planning and Conservation League Foundation
In Partnership with
The Carmel River Watershed Conservancy
PWA
Prepared by
Philip Williams & Associates, Ltd.
with
PHILIP WILLIAMS & ASSOCIATES, LTD
ENVIRONMENTAL HYDROLOGY Ecosystem Management International
Philip Williams & Associates, Ltd. | 550 Kearny Street, Suite 900 | San Francisco CA 95108 | t: 415.262-2300 | www.pwa-lPtdW.cAo mRe f. # 1879
SUPPLEMENTAL CARMEL RIVER
WATERSHED ACTION PLAN
Prepared for
The Planning and Conservation League Foundation
In partnership with the Carmel River Watershed Conservancy
Prepared by
Philip Williams & Associates, Ltd.
with
Ecosystem Management International
March, 2007
PWA REF. # 1806.00
This report has been produced by the Planning and Conservation League
Foundation in partnership with the Carmel River Watershed
Conservancy. Funds were provided in part by the State Water Resources
Control Board (Proposition 13) and by the State Coastal Conservancy.
In this effort, the Planning and Conservation League Foundation has
engaged with local residents, community-based nonprofit organizations,
regional and state agencies to support efforts to develop a watershed
action plan for the Carmel River Watershed that benefits the communities
of the Carmel Valley as well as the residents of the State of California.
Services provided pursuant to this Agreement are intended for the use
and benefit of the Planning and Conservation League Foundation, the
State Water Resources Control Board and the State Coastal
Conservancy.
TABLE OF CONTENTS
Page No.
EXECUTIVE SUMMARY E-1
1. INTRODUCTION 1
1.1 OVERVIEW OF DOCUMENT STRUCTURE 2
1.2 THE CARMEL RIVER WATERSHED 2
1.2.1 Groundwater Pumping and Diversions 6
1.2.2 Dams on the Carmel River 6
1.2.3 Carmel River Estuary 9
1.2.4 Water Quality in the Carmel River and Estuary 12
1.2.5 Existing Human Infrastructure 12
1.3 PREVIOUS PLANNING AND RESTORATION EFFORTS 12
2. KEY ISSUES AND ASSOCIATED IMPACTS 16
2.1 RIPARIAN AQUIFER WITHDRAWALS 16
2.2 SAN CLEMENTE DAM 19
2.2.1 Risk to Public Safety 21
2.2.2 Altered Sediment Transport and Channel Geomorphology 21
2.2.3 Disconnected Floodplain and Reduced Flow 24
2.2.4 Disruption of Ecological Integrity 24
2.3 SEDIMENT TRANSPORT AND RIVER MANAGEMENT 25
2.3.1 Current Disruptions to Physical Processes and
Geomorphology of the Carmel River 27
2.3.2 Potential Impacts of Renewed Sediment Supply 30
2.4 RESTORATION NEEDS 33
2.4.1 Ecological Functions and Processes 33
2.4.1.1 Loss of Streamside Vegetation 33
2.4.1.2 Increased Invasion by Non-native Species 36
2.4.1.3 Modified Aquatic Food Chains 37
2.4.1.4 Loss of Coastal Salt Marsh Habitats 37
2.4.1.5 Reduced Water Quality in Estuary 38
2.4.1.6 Discontinuity of Habitats 39
2.4.2 Effects on Key Species 41
2.4.2.1 Steelhead Trout 42
2.4.2.2 California Red-legged Frog 46
3. PRINCIPLES FOR A FUNCTIONALLY RESTORED WATERSHED 50
3.1 INTEGRATING HUMAN INFRASTRUCTURE WITH ECOSYSTEMS 51
4. RECOMMENDED ACTIONS 52
4.1 REDUCE PUMPING FROM THE RIPARIAN AQUIFER 52
4.1.1 State Water Resources Control Board Order WR 95-10 and CAW Pumping 53
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4.1.2 Private Pumping 53
4.1.3 Benefits of Discontinuing Riparian Groundwater Pumping 53
4.2 REMOVE SAN CLEMENTE DAM 54
4.2.1 Essential Components for Post-Dam Site Design and Management 55
4.2.1.1 Criteria for On-site Restoration – An Eco-Geomorphic
Approach 56
4.2.1.2 On-site Sediment Storage 57
4.2.1.3 By-pass Channel Design 58
4.2.1.4 Monitoring and Adaptive Management 60
4.2.2 Benefits of Dam Removal with Eco-Geomorphic Restoration 60
4.3 DEVELOP A SEDIMENT MANAGEMENT STRATEGY FOR POST-DAM
CONDITIONS 64
4.3.1 Evaluating Impacts from Changing Sediment Supplies 65
4.3.2 An Integrated System of Sediment and Runoff Management Controls 67
4.3.3 Benefits of Sediment Management Actions 70
4.4 INTEGRATE SOLUTIONS INTO A CARMEL RIVER WATERSHED
RESTORATION PROGRAM 71
4.4.1 Purpose 74
4.4.2 Key Objectives and Work Plan 74
4.4.3 Structure and Funding Ideas 78
4.4.4 Scientific Research on Dam Removal 79
5. REFERENCES 80
6. LIST OF PREPARERS 85
LIST OF APPENDICES
Appendix A. Key Species List
Appendix B. Frequently Asked Questions
Appendix C. Eco-Geomorphic Conceptual Model
Appendix D. Adaptive Management

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LIST OF TABLES
Table 1. Total Available Spawning and Rearing Habitat (NOAA, 2005) 42
Table 2. Potential Rearing Habitat for Steelhead Trout (NOAA 2001) 43
Table 3. Total Steelhead Rearing Habitat Carrying Capacity 43
LIST OF FIGURES
Figure 1-1. Carmel River Watershed 4
Figure 1-2. Groundwater Pumping Station along the Carmel River 7
Figure 1-3. San Clemente Dam 8
Figure 1-4. Carmel Lagoon Following Construction 10
Figure 1-5. Restored Carmel Lagoon 11
Figure 2-1. Carmel River Aquifer 18
Figure 2-2. Typical Summertime River Conditions Along Pumping Zone 20
Figure 2-3. Flood Conditions at San Clemente Dam 22
Figure 2-4. San Clemente Dam and Reservoir 23
Figure 2-5. Incised Reach of the Carmel River 26
Figure 2-6. Residential Homes Along the Carmel River 28
Figure 2-7. Longitudinal and Lateral Channel Responses to the San Clemente Dam 29
Figure 2-8. Typical Response of the Downstream Riparian Community to Dam Removal 31
Figure 2-9. Typical Responses to Dam Removal with Associated Timeframes 32
Figure 2-10. Cumulative Effects of Dams 34
Figure 2-11. Key Landscape Drivers of Cumulative Impacts 35
Figure 2-12. Land-use Distribution in the Lower Carmel River 40
Figure 2-13. California Red-legged Frog 47
Figure 4-1. Stored Alluvial Sediment Integrated with Eco-geomorphically Functional Conditions 59
Figure 4-2. Example of Functional Geomorphic Channel Design 61
Figure 4-3. Eco-geomorphic Design Incorporates Channel, Floodplain, and
Vegetation Components 63
Figure 4-4. Existing Floodplain Functions 66
Figure 4-5. In-channel Structures Designed to Hold Channel Integrity and
Provide Sediment Storage 68
Figure 4-6. Linkages between Key Watershed Processes Supports the Need for an Integrated
Management Solution 72
Figure 4-7. Components of an Integrated Watershed Restoration Program 73
Figure 4-8. Inputs and Outcomes Associated with the Integrated Watershed Restoration Program 75
Figure 4-9. Landscape Functions for the lower Carmel River 77
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EXECUTIVE SUMMARY
The Carmel River presents one of the most significant opportunities for river restoration
on California’s Central Coast. Flowing through the Ventana Wilderness and the Los Padres
National Forest, the Carmel River provides essential wildlife habitat for important species,
including the state and federally listed steelhead trout and California red-legged frog.
Since 1921, the San Clemente Dam has impacted the Carmel River and its wildlife
resources. As a result, the Carmel River suffers accelerated erosion, its once vibrant steelhead run
has dramatically decreased, and lives and property below the dam are threatened with potential
dam collapse and inundation by sediment currently trapped behind the dam. In addition,
groundwater pumping in the lower river basin seasonally dewaters the Carmel River channel in
many years further impacting sensitive habitat and wildlife.
This report, the Supplemental Carmel River Watershed Action Plan, analyzes the
extraordinary opportunities that now exist to remove the antiquated dam, reduce downstream
groundwater pumping, and implement an integrated watershed restoration and sediment
management strategy that will bring this river back to life. This Supplemental Action Plan focuses
on opportunities to provide benefits to the downstream community and the public through
restoration of the Carmel River Watershed. The following paragraphs outline these opportunities
and benefits.
A Public Safety Risk Will Be Eliminated
The San Clemente Dam poses a significant threat to lives and property. The State has
determined that this dam could fail during a magnitude 6.5 or greater earthquake, releasing over
2.1 million cubic yards of sediment trapped above the dam. Removal of San Clemente Dam
would expedite resolution of the seismic safety issue that now threatens 1500 homes,
infrastructures, vineyards and commercial buildings downstream of the dam. Allowing the dam
structure to remain in place would require long-term management of associated impacts to the
river ecosystem, including significant costs, to assure sediment management problems and
challenges posed by the existence of a dam structure are fully addressed.
Threatened Species Will be Restored
San Clemente Dam is a barrier to threatened south central population of steelhead trout.
Nearly half of the natural spawning habitat and three-quarters of the potential rearing habitat is
located above the dam. The existing 85-foot fish ladder prevents many adult fish from accessing
upstream habitat areas while no provision exists to guide downstream migrating juvenile trout
and smolts. The Carmel River once boasted an estimated steelhead run of 10,000 to 20,000 fish,
and now, less than 700 fish return to the Carmel River each year. Though small, the Carmel River

E-1
steelhead population is genetically important. The National Oceanic and Atmospheric
Administration has determined that the Carmel River steelhead run is a critical foundation and
source population that is essential for the recovery of steelhead on the Central Coast. Removal of
San Clemente Dam would contribute to recovery of this important trout population and restore
access to seven miles of river habitat now blocked by the dam.
The California red-legged frog is a threatened amphibian found in the Carmel River
Watershed. Impacts related to development and changes in the dynamics of sediment and water
regimes have impacted its habitats. San Clemente and Los Padres dams and downstream
groundwater pumping have changed the hydrologic regime of the Carmel River and resulted in a
disconnecting of the river from the floodplain and wetlands. Restoring the Carmel River physical
and hydrologic processes will provide and opportunity to restore habitats for the frog and prevent
its extirpation in the watershed.
Sediment Transport Will be Re-Established
The San Clemente Dam has captured sediment from the upper half of the 255 square-mile
Carmel River Watershed. The loss of a natural sediment regime in the lower river has resulted in
channel incision and coarsening of the riverbed. This in turn has degraded the habitat in the
Carmel River and decreased the production of macroinvertebrates, the primary food of
endangered steelhead trout. Lack of seasonal sediment regime has contributed to accelerated
erosion of the Carmel River channel, lagoon and beach habitats. Erosion threatens to destabilize
homes and roads adjacent to the Carmel River lagoon. Removal of San Clemente Dam would
establish a new natural sediment regime on the Carmel River. This would help restore natural
channel processes in the River’s lower reaches and contribute to improved habitat in the river
channel.
Working Toward Restoration
This Supplemental Carmel River Watershed Action Plan has been developed by the
Planning and Conservation League Foundation in partnership with the Carmel River Watershed
Conservancy. The Plan focuses on two primary activities as key components of a restoration
strategy: removal of San Clemente Dam and cessation of downstream groundwater pumping.
The Supplemental Carmel River Watershed Action Plan builds on existing research,
management and restoration work being done in the watershed. It is based upon understanding
that complex ecological and geomorphic processes affect watersheds. It presents information that
describes how human actions at one location have influences throughout the watershed. The
cumulative effect of these actions has led to a disrupting of the ecological processes in the
watershed. Resolving these problems cannot be accomplished by independent actions. Instead a
coordinated approach to watershed restoration must be employed that focuses on specific actions
that cumulatively work together to support ecological restoration. This Plan outlines how to
manage those human and natural influences and strategically accomplish tasks to achieve a

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sustainable, self-maintaining watershed that supports fish, wildlife, protects water quality, and
provides for human needs.
The Supplemental Action Plan presents several key recommendations, including
establishing a coordinated Carmel River Watershed Restoration Program. By integrating the
information and recommendations provided in this report, implementation of a Restoration
Program can link current opportunities with the potential benefits of future restoration needs that
will occur as resolution to the dam seismic problem goes forward, and as a solution is identified
for State Water Board Order 95-10. A key objective of the Carmel River Watershed Restoration
Program is to provide the organizational structure necessary to achieve these and other goals
articulated in this report. Recommended actions for implementation of the Restoration Program
will:
ƒ Provide an integrated scientific and management organization that can identify
problems, set priorities, find solutions, and track progress. The program can take a lead
role in identifying lead agencies for various projects, establishing funding, provide
staffing and other resources, and ensure effective accountability.
ƒ Facilitate collaboration and coordination among stakeholders. The success of the
program will depend on the cooperation of many agencies, entities, landowners, and
other stakeholders. The program will promote an integrated approach throughout the
watershed that can act to remove existing barriers to cooperation.
ƒ Establish and maintain a working conceptual model for the interactions between the
various geomorphic, ecological, biological, social and political systems within the
watershed. This will provide a common basis for management actions that can be used
by all agencies, landowners, and managers within the watershed to prioritize actions and
serve as a roadmap for restoration.
A Vision for a Restored Carmel River Watershed
The vision of a restored Carmel River Watershed described in this document is based on
the understanding that management actions should encourage the river to restore itself through
natural processes that result in a more resilient and sustainable watershed ecosystem. Restoring a
fully functional watershed will contribute to numerous valuable environmental services and
functions that will meet both human and ecosystem needs. A functioning watershed ecosystem
can minimize flood risks, recycle nutrients, purify water, augment and maintain stream flow,
recharge groundwater, provide habitat for fish and wildlife, and provide recreation for people.
Achieving these benefits will require collaboration among many stakeholders including
landowners, local nonprofit organizations, state and federal agencies. Through their collective
efforts, actions to prioritize and implement restoration on a watershed scale will promote
successful outcomes from the headwaters to the coastal estuary and lagoon, and assure a healthy
future for the Carmel River Watershed.
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1. INTRODUCTION
The Carmel River Watershed exhibits the effects of changes to the natural environment that have
occurred through time, as well as human impacts that have occurred in the last 150 years. Natural
environmental processes are influenced by geology, climate, vegetation, and topography. Key
natural processes include fire, floods, landslides, vegetation succession, and wind. Human
impacts in the watershed are typically related to development, water management, land
management, forestry practices, and infrastructure, including the construction of dams on the
river.
The Carmel River Watershed has significant long-term physical and biological problems that
require watershed-based solutions. The impact of upstream San Clemente and Los Padres dams,
groundwater withdrawals along the lower Carmel River, and current management of the Carmel
River Estuary have negatively impacted the ecological and physical character of the river and the
aquatic, avian, amphibian and terrestrial wildlife that it supports.
The vision of a restored Carmel River Watershed described in this document is based on the
understanding that management actions should provide the river with the physical processes to
restore itself through natural actions. As the physical processes are restored, the biological
processes will occur. These actions will ultimately lead to a more resilient and sustainable
watershed ecosystem. Restoring a fully functional watershed will contribute to numerous
valuable services and functions that will meet both human and ecosystem needs. A functional
watershed can minimize flood risks, recycle nutrients, purify water, augment and maintain stream
flow, recharge groundwater, provide habitat for fish and wildlife, and provide recreation for
people.
This report entitled, The Supplemental Carmel River Watershed Action Plan, was funded by the
State of California Coastal Conservancy and the California State Water Quality Resources
Control Board. This report augments the Carmel River Watershed Assessment and Action Plan
(Carmel River Watershed Conservancy 2005), which identified and summarized many of
the major issues facing the Carmel River Watershed based on numerous technical and scientific
documents that have been developed specifically for the Carmel River. This report also
synthesizes information from reports developed by NOAA (2002, 2001), USFWS (2002), the
Environmental and Biological Assessment of portions of the Carmel River Watershed (MPWMD
2004), and the Physical and Hydrological Assessment of the Carmel River Watershed (Smith, et al.
2004). The goal of the Supplemental Plan is to provide recommendations for restoring the Carmel
River Watershed ecosystem under a scenario of: a) discontinued riparian aquifer/groundwater
withdrawals, and b) removal of the San Clemente Dam..
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