Aliso Creek - Watershed Management Plan Chapter III
Bridge over looking Aliso Creek

CHAPTER III: RECOMMENDED MANAGEMENT ACTIONS III-1
3.1 Introduction III-1
3.2 Multi-Objective Planning III-1
3.2.1 Aliso Creek Mainstem Ecosystem Restoration III-2
3.2.2 Sulphur Creek Ecosystem Restoration III-3
3.2.3 Wood Canyon Ecosystem Restoration III-3
3.2.4 English Canyon Ecosystem Restoration III-4
3.2.5 Pacific Park Basin Ecosystem Restoration III-4
3.2.6 Expansion of Program, Monitoring, and Evaluation of Best Management Practices (BMPs) III-4
3.2.7 Small Wetlands for Water Quality III-5
3.2.8 Bank Stabilization Study - SOCWA Treatment Plant III-5
3.2.9 English Canyon Erosion Control III-5
3.2.10 Floodproofing at Aliso Creek Inn III-6
3.2.11 Watershed Education III-6
3.2.12 Water Quality Monitoring Plan III-7
3.2.13 Exotic Species Eradication Program III-8

Chapter III: Recommended Management Actions

3.1 Introduction

This chapter discusses the recommendations that address the water resource issues described in Chapter 2. The recommendations generally reflect those that the Study Management Team agreed would best address the needs and requirements of each of the water resource problem. The timeframe for recommendations generally ranges from 0 to 5 years for implementation to be initiated.

The Aliso Creek Study Management Team (SMT) is composed of the study partners who provided financial support, direction, data, and conducted analytical studies. The study partners include:

• U.S. Army Corps of Engineers, Los Angeles District
• County of Orange
• City of Aliso Viejo
• City of Laguna Beach
• City of Laguna Hills
• City of Laguna Niguel
• City of Laguna Woods
• City of Lake Forest
• City of Mission Viejo
• Aliso Water Management Agency
• El Toro Water District
• Los Alisos Water District
• Municipal Water District of Orange County
• Moulton Niguel Water District
• South Coast Water District

The SMT also include representatives from other government agencies, non-governmental organizations, special interest groups, and watershed residents.

Historically, natural resource management planning has been done on one resource only, or to deal with a single problem. The WMP is an attempt to begin integrating the many parts of the watershed through recommendations for practices and programs developed with the complexity of the Aliso Creek system in mind. Voluntary implementation of the recommendations in this WMP will not only help deal with identified problems, but will prevent others from occurring. Solutions to problems identified by citizens, agencies, public interest groups, etc. are easily realized when problems are treated as interests to be addressed instead of positions to be defended. This WMP provides a first step toward the mutual education within the community that will provide the basis for broad cooperative actions. No amount of government funding or regulation can equal the effects of broad voluntary participation on the part of individuals in the effort to provide long-term protection to the Aliso Creek watershed's natural resource system.

The Aliso Creek Watershed Management Feasibility Report presents and evaluates various structural and non-structural management measures to address a range of specific problems occurring in the Aliso Creek watershed. Throughout the watershed study, iterations of screening were conducted to ensure the development of efficient and effective solutions. Some measures were deemed not viable based on engineering analysis, environmental soundness, and public acceptability. The following sections describe the management measures that were recommended for inclusion in an integrated WMP. Implementation of these measures will require a continued cooperative effort among the various stakeholders.

3.2 Multi-Objective Planning

In general, stream work in the Aliso Creek watershed for the past several decades addressed only one issue at a time. Usually, stream alteration was done for flood hazard reduction, and relied heavily on engineered channels. Maintenance of these projects is particularly costly, and other aspects of the river system, such as vegetated and riparian corridors, wetlands, public recreation, and geomorphological stability were not fully considered in the final product. Wildlife enhancement projects frequently focused only on wildlife and did not consider flood threat impacts of the enhancement work. Drainage work for urban uses often did not consider either flood control or wildlife in their design and construction. A multi-objective approach to Aliso Creek watershed development and enhancement includes all these factors and seeks to recreate a sustainable system that requires much less long-term maintenance and provide a far greater range of benefits. By anticipating and utilizing the natural energy of the creek, a complete design accommodates channel stabilization, flood hazard reduction, economic uses, aesthetic and recreational opportunities, and habitat concerns.

3.2.1 Aliso Creek Mainstem Ecosystem Restoration

This management measure proposes stream restoration and stabilization of the Aliso Creek in the reach beginning just upstream of the South Coast Treatment Plant and ending at the Pacific Park Drive. The components are as follows:

• Lower Aliso Creek Stabilization Plan, a measure that includes a series of low riprap drop (or "riffle") structures with pools in between. The pools will have the long-term equilibrium slope necessary for a stable channel while the drops provide the fall necessary to meet the overall gradient of the creek. Each structure consists of a buried soil cement grade control, a grouted riprap riffle slope, a dumped riprap scour pad, and a side slope of open-celled articulated concrete revetment (e.g., Armorflex) with vegetation planted in the voids. This stabilization measure begins in the reach just upstream of the South Coast Treatment Plant and ends at the Aliso Water Management Agency (AWMA) Bridge.
• Middle and Upper Aliso Creek Stabilization Plan extends the pool and riffle concept into the Aliso Creek reach beginning just upstream of the AWMA access road bridge and ending at Normandale. The riffles are intended as a replacement for the vertical concrete drops that currently segment the stream and restrict movement of aquatic, amphibious, and terrestrial wildlife species. The existing riprap will be removed and replaced with vegetation.
• Floodplain Riparian Habitat proposes to flatten and terrace the vertical banks. In terms of stream stabilization, the modified sections will reduce stream velocities and unit discharges, and will be less erosive. In terms of restoration, the flattened slopes will provide a stable surface for plantings and for establishment of riparian and upland habitat. With a stable profile combined with flattened, terraced, and vegetated side slopes, lateral instability will be reduced.
• Off-Channel Aquatic Habitat and Riparian Restoration proposes to construct an off-channel riparian and aquatic habitat in the abandoned oxbow near the confluence of Aliso Creek and Wood Canyon. A low-flow channel would be constructed along the outside of the abandoned bend with the appropriate depth, velocity, substrate, and vegetation to provide for fish spawning and rearing. The side slopes would be vegetated with emergent, riparian, and upland species at the appropriate elevations.
• Modify Existing Grade Control Structures (Interim Measure): The two 10-foot vertical concrete drops located upstream of the AWMA road bridge result in wide shallow ponding on the upstream side. This ponding can be eliminated by cutting a low-flow triangular notch in each of the structures. This measure is a low-cost, interim solution that will immediately reduce ponding, but is not considered a permanent restoration alternative.
• Aliso Creek Riparian Revegetation Plan involves the planting of native vegetation within this reach of the Aliso Creek mainstem.

TOTAL ESTIMATED COST: $16 million

The positive effects of this management measure include:

• Reduced erosion in the Aliso-Wood Canyon reach
• Removal of barriers to wildlife movement; Increased terrestrial wildlife connectivity
• Water quality improvement by aeration and temperature reduction for the low flows
• Attenuation of certain pollutants
• Creation active floodplains
• Riparian revegetation
• Restoration of floodplain moisture
• Reestablishment of native species

3.2.2 Sulphur Creek Ecosystem Restoration

• This management measure proposes restoration of Sulphur Creek in the reach beginning just upstream of the water treatment plant to the community center access road along Crown Valley Parkway. This involves the modification of the existing flow control structure at the upstream boundary of the reach, modification of the small basins at the upstream and downstream ends of the reach, restoration of the riparian terraces and stabilization of side slopes, and reestablishment of native riparian vegetation.
  
• The measure also proposes to restore riparian habitat in the reach along the Crown Valley Parkway between La Plata Drive and Moulton Parkway. This includes the replacement of the concrete low-flow V-ditch with a natural meandering low flow channel, removal of non-native species, as well as reestablishment of native riparian vegetation.

TOTAL ESTIMATED COST: $2 million

The positive effects of this management measure include:

• Restore natural hydrologic regime
• Restore and stabilize riparian terraces
• Reestablish riparian vegetation
• Restore aquatic habitat

3.2.3 Wood Canyon Ecosystem Restoration

The restoration alternatives included in this management measure are as follows:

• Gabion Removal and Stream Restoration which proposes to remove the 300-foot gabion structure and realign the tributary from the end of the culvert until its terminus at the Wood Canyon Creek. Modification would include stream lengthening and meander restoration, creation of wetlands, and reestablishment of native riparian vegetation.
• Restoration at the Wood Canyon Detention Basin proposes to modify the outlet of a detention basin located at the upstream extent of Wood Canyon.
• Localized Stream Restoration addresses localized erosion and stream degradation sites located in the heavily vegetated portion of upper Wood Canyon, approximately 3 miles from the gate at the AWMA Road gate.

TOTAL ESTIMATED COST: $550,000

The positive effects of this management measure include:

• Reduced erosion in the Wood Canyon reach
• Create wetlands
• Riparian revegetation
• Water quality improvement through filtration

3.2.4 English Canyon Ecosystem Restoration

This management measure proposes to restore emergent wetland and riparian habitat along the English Canyon Creek between the confluence with Aliso Creek and Los Alisos Boulevard. This would include the removal of riprap and exotic species, limited excavation and regrading of the north bank of the creek (between the Aliso Creek confluence and the existing culvert at the Los Alisos crossing), and the reestablishment of native riparian vegetation.

TOTAL ESTIMATED COST: $660,000

The positive effects of this management measure include:

• Reestablish emergent wetland and riparian vegetation
• Water quality improvement through filtration and sediment retention
• Water temperature reduction by added shade

3.2.5 Pacific Park Basin Ecosystem Restoration

The proposed measure is located just upstream of Pacific Park Drive. The area under consideration extends from Pacific Park Drive to the San Joaquin Hills Transportation Corridor and is bound by the ball fields on the west and the road embankment on the east.

This measure proposes an emergent freshwater wetland and riparian habitat along a 2,460-foot section of Aliso Creek within the existing Pacific Park detention basin.

TOTAL ESTIMATED COST: $260,000

The positive effects of this management measure include:

• Construction of new habitat
• Encourage development of biodiversity in the watershed
• Water quality improvement through filtration and sediment retention
• Water temperature reduction by added shade

3.2.6 Expansion of Program, Monitoring, and Evaluation of Best Management Practices (BMPs)

This program involves expansion of the BMP Program to include on-site biofiltration, landscape controls, and enforcement of ordinances on pet waste disposal. It also provides for a detailed review of design and development standards for Orange County and associated cities within the Aliso Creek watershed. The review should be based on the need to have water quality controls on stormwater runoff as well as water quantity management. Also, the review needs to address BMPs from the perspective of implementation and effectiveness relative to water quality benefits.

Monitoring programs (i.e., Orange County NPDES Stormwater Program Drainage Area Management Plan, Management guidelines for the use of Fertilizers and Pesticides, etc.) to evaluate effectiveness of current standards need to be implemented. This will identify opportunities for retrofitting current facilities and modifying standards.

TOTAL ESTIMATED COST: Variable based upon the intensity of the program developed.

The positive effects of this management measure include:

• Generate information needed to continue BMP program, or develop new measures if BMPs are not effective
• Encourage individual participation in BMPs by showing BMPs values to watershed

3.2.7 Small Wetlands for Water Quality

This management measure proposes to construct wetlands or wet detention areas at the confluences of Dairy Fork/Aliso Creek and English Canyon/Aliso Creek. At each location, the wetland area would be shaped by a combination of excavation and fill to provide for a variety of habitats, ranging from a relatively deep water zone to shallow water zone, with dry islands that support riparian vegetation and provide shading.

TOTAL ESTIMATED COST: $1.5 million

The positive effects of this management measure include:

• Construction of new habitat
• Encourage development of biodiversity in the watershed
• Water quality improvement through filtration and sediment retention

3.2.8 Bank Stabilization Study - SOCWA Treatment Plant

This measure proposes to address the potential for failure of the South Orange County Wastewater Authority Treatment Plant bridge. An abandoned, encased sewer pipe crosses the invert at grade immediately upstream of the bridge. This pipe contains residual sewage solids and is a potential health threat if it breaks. The modification includes installation of a soil cement grade control immediately downstream of the bridge, pavement of the invert with riprap, and capping and removal of the pipe.

TOTAL ESTIMATED COST: $300,000

The positive effects of this management measure include:

• Prevention of sewage spill into Aliso Creek
• Prevention of bridge failure
• Restoration of aquatic species passage
• Revegetation

3.2.9 English Canyon Erosion Control

This management measure proposes to (a) install riprap bank protection on the outside of a bend on English Canyon Creek between Los Alisos Boulevard and Trabuco Road. The bend may potentially threaten Los Alisos Boulevard. The measure will also repair the existing scour holes downstream of the Via Noveno and Vista del Lago bridges, and below the pipe outlet just downstream of Entidad. The scour, if unchecked, could eventually threaten the structures.

TOTAL ESTIMATED COST: $790,000

The positive effects of this management measure include:

• Streambank stabilization
• Decreased erosion
• Protection of existing infrastructure

3.2.10 Floodproofing at Aliso Creek Inn

Within the watershed, there are several locations at which flood damages can not be addressed by cost-effective flood control solutions that would address more than a single beneficiary. This appears to be the case in the lower reach of the Aliso Creek watershed. There are six general non-structural floodproofing methods to reduce the occurrence of flooding and/or the hazards associated with flood events. These include the following:

• Structure elevation
• Levees and floodwalls
• Wet floodproofing
• Dry floodproofing
• Relocation
• Demolition

None of the floodproofing methods above has been identified as an economically viable option. Unless a source of funds could be identified which is not tied to benefit-cost analyses, the current situation will continue. A flood warning system may be a viable alternative to structural measures at this site, should there be a desire to pursue this option.

ESTIMATED COSTS:

• Structure elevation $6.4 million
• Levees/floodwalls $1.6 million
• Wet floodproofing Not viable
• Dry floodproofing $764,000
• Relocation $8.2 million
• Demolition $5.4 million

3.2.11 Watershed Education

Watershed Education Plan

The goal of this management measure is to provide technical guidance for the development of local education program for K-12 that addresses scientific and cultural impacts of urbanization as it specifically relates to the Aliso Creek watershed. A significant opportunity exists by directing some of the potential community service hours required by some of the high schools into a focus on the watershed ecology and monitoring.

The curriculum program should help students develop a sense of stewardship toward their environment and community, and give them a background to make educated and informed decisions regarding wise resource management as part of their day to day life. The program should also focus on observation and appreciation, relationships and interaction, and how an understanding and application of scientific principles impacts watershed management, policies, and regulations.

In addition to the local schools and universities located within the watershed, there is a need for additional facilities that are dedicated to watershed program activities and community education. The opportunity for siting and developing an education center that provides a staging area for research-oriented science programs and community education should be further explored. Funding mechanisms for such a facility may be pursued through public-private partnerships with corporate sponsors contributing to the operation and maintenance of the facility.

TOTAL ESTIMATED COST: Variable based upon the intensity of the program developed

• The positive effects of this management measure include:
• Short-term environmental restoration improvements associated with field exercises
• Long-term environmental benefits associated with stewardship and modification of behaviors
• Community consensus for watershed management need and direction

Also includes:

Non-Point Source Public Awareness

This element represents the second component of the overall education initiative. This effort targets the remainder of the general public living, recreating, vacationing, or conducting business within the Aliso Creek watershed.

The public awareness program would target the residents and businesses within the watershed informing them how their activities have a direct influence on the creek and its quality. There is a general lack of understanding and limited information available to residents and proprietors about the purpose and impacts of best management practices (BMPs) that they can implement themselves. Appendices A and B provides recommendations on management practices that can influence the water quality in the Aliso Creek watershed. These recommendations promote and encourage practices and behavior that will support development and maintenance of a healthy environment for the Aliso Creek watershed.

TOTAL ESTIMATED COST: Variable based upon the intensity of the program developed.

The positive effects of this management measure include:

• Improvements in water quality
• Improvements in stormwater runoff
• Improvements in environmental quality
• Improvements in instream habitat in Aliso Creek
• Public awareness of cause and effect relationship of individual actions to watershed health

3.2.12 Water Quality Monitoring Plan

Water quality monitoring is an iterative process that will develop as the needs for subsequent sampling are determined by previous results. Availability of funding can also be a constraint for continued sampling. As presented in Appendix C of this document, a volunteer program is proposed to involve the public in monitoring of the Aliso Creek watershed. This would increase public awareness of the status of Aliso Creek as well as supplement data available to agencies involved. A generic water quality monitoring plan is presented in Appendix D for the continued monitoring of the Aliso Creek watershed.

TOTAL ESTIMATED COST: Variable based upon the intensity of the program developed

The positive effects of this management measure include:

• Determine if Aliso Creek meets water quality standards
• Encourage individual participation in BMPs and watershed issues

3.2.13 Exotic Species Eradication Program

The goal of this program is to enhance habitat by allowing native plants to reestablish in the areas where non-native species have displaced natives. This plan would include removal and control approaches, as well as public education, such as why planting these species in their yards affects the watershed. The plan will also outline an annual monitoring element to track the progress of eradication and to locate any new outbreaks of the species within the Aliso Creek watershed. The exact methods used to eradicate the plants will depend on several factors, but the use of volunteer resources including school program should be explored. However, due to castor bean's potential toxicity, children should not carry out physical removal and handling of this species. The effective removal of thistle will probably incorporate herbicides, which also limits the range of volunteer action that could be taken. A program outline is presented in Appendix D.

TOTAL ESTIMATED COST: Variable based upon the intensity of the program developed. Currently estimated at $9 million.

The positive effects of this management measure include:

• Reestablishment of native vegetation that provides higher-valued, diverse habitat

Overall, the watershed resource issues and recommended management actions discussed in this WMP could be summarized into the following common themes:

• Preservation, conservation, enhancement, and restoration of natural resources in the Aliso Creek watershed;
• Conservation and improvement of water quality and quantity;
• Utilization of environmentally sound land use practices;
• A need to reduce overlap and duplication of services and programs offered for resource management; and
• Communication needs for resource management

Taking Responsibility

All stakeholders must recognize their responsibility in natural resource management. Environmental issues and concerns in the Aliso Creek watershed need to be addressed promptly and efficiently. The state of the environment must not fall victim to "finger pointing" or financial constraints. Watershed stakeholders need to continue to work cooperatively to improve, preserve, enhance, and rehabilitate the environment.

Streamlining and Coordination

Resource management programs and services must be streamlined and coordinated to provide an efficient delivery of services.

Partnerships

Partnerships between any stakeholder group involved in watershed planning and management need to continue. Regardless of who is involved in the process, partnerships are an effective solution to many resource management issues in the Aliso Creek watershed.

Policy Implementation

Where there is significant concern for a particular resource and no policy is in place, efforts should be made to establish a local policy.

Effective Communication

People need to be informed and educated about natural resource management. Effective communication is a key component to watershed planning and management. It can change attitudes, create awareness, improve land use practices, and improve relations between watershed stakeholders.

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