Arroyo Seco Watershed

Restoration Feasibility Study – Phase II  

 

Framework for Restoration Projects  

On May 20, 2002 North East Tress and the Arroyo Seco Foundation submitted the Final Report of the Arroyo Seco Watershed Restoration Feasibility Study to the California Coastal Conservancy.  Now you can review the Goals and the Projects contained in that report. 

 

Restoration Goal 1:  Restore the natural hydrological functioning of the watershed

 

1.1

Restore Arroyo Seco stream and tributaries through widening and lengthening of streams.

1.1.1

Remove the concrete lined channel, and replace it with a naturally functioning stream where possible:

§         Create meanders and braiding in stream

§         Restore floodplains

1.1.2

Restore creek tributaries:

§         Enhance drainage swales

§         Daylight creek tributaries

1.1.3

Conduct a detailed hydraulic analysis of the modified channel and floodplain.

1.1.4

Conduct a detailed geomorphic analysis to determine an appropriate combination of channel sinuosity and channel geometry.

1.1.5

            Formulate program for multi-objective operation and maintenance of restored system that is adaptable by all management agencies.

1.2

            Create floodplain system allowing for periodic channel overflows while maintaining existing level of public safety.

1.2.1

Mitigate existing flood hazard conditions.

 

1.2.2

Utilize existing open spaces along Arroyo Seco and tributaries for floodplain restoration.

1.3

Reduce volume and velocity of storm water runoff.

1.3.1

Utilize multiple-purpose BMPs and management practices such as reforestation, bioengineering, and/or other non-structural approaches for flood management.

1.3.2

Implement flood attenuation measures in subwatersheds through increased groundwater percolation and slowing of surface runoff.

1.3.3

Utilize non-structural, aquatic habitat-friendly grade control measures.

1.3.4

Utilize neighborhood-based flood detention solutions.

1.3.5

Restrict hillside development.

1.3.6

Evaluate the effects of BMPs on volume & velocity of storm water.

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Restoration Goal 2:  Better Manage, Optimize, & Conserve Water Resources While Improving Water Quality

 

2.1

Improve quality of surface water for aquatic habitat and human contact.

2.1.1

Implement BMPs to mitigate water quality pollutants flowing into the Arroyo Seco.

2.1.2

Develop source protection measures.

2.1.3

Reduce non-point sources of pollution.

2.1.4

Develop ongoing water quality monitoring programs and public education of water quality issues.

2.1.5

Monitor and clean out pollutants that accumulate in non-structural BMPs.

2.1.6

Evaluate existing point-sources of pollution for monitoring compliance on a regular basis.

2.2

Restore the quality and quantity of water recharge to the Raymond Aquifer.

2.2.1

Increase permeability of developed land uses through implementation of BMPs such as redirecting runoff into bioswales, removing unneeded concrete and asphalt.

2.2.2

Manage groundwater to prevent future overdraft.

2.2.3

Mitigate water quality pollutants percolating into the groundwater.

2.2.4

Test the feasibility of recharging the groundwater basin with surface flows in the channel through Hahamongna Basin.  Requires a detailed monitoring program and cooperation by groundwater users.

2.2.5

Develop detailed water budget to assess current inputs and outputs of rainfall, imported water and groundwater for the hydrologic cycle of the watershed. One purpose includes assessing the potential overdraft of groundwater.

2.2.6

Promote program that encourages all property owners to take responsibility for retaining 50% of the “first flush” of storm water or similar benchmark onsite.

2.3

Develop groundwater management strategy for optimum use of local water resources.

2.3.1

Expand conjunctive use of groundwater basin for enhanced storage during wet periods for use during dry periods.

2.3.2

Preserve foothill open space to protect percolation into the groundwater basin and to prevent aggravated runoff.

2.4

Reduce dependence on imported water.

2.4.1

Increase groundwater percolation through BMPs.

2.4.2

Promote comprehensive conservation programs and best management practices throughout the watershed to reduce water consumption.

2.4.3

Develop upper hillside watershed reforestation and revegetation programs to improve local retention.

2.5

Reinstate sediment transport.

2.5.1

Control erosion & manage sedimentation in restored streams (e.g., bank regrading and revegetation, channel grade control structures, riprap), and under bridges & freeway overpasses.

2.5.2

Implement BMPs for construction and existing land uses to reduce and manage sedimentation from human disturbance.

2.5.3

Conduct a detailed hydraulic and geomorphic investigation of channel conditions with respect to erosion potential.

2.5.4

Establish a maintenance and management program to either trap the sediment in areas where it can be easily processed or to promote its passage through Devil’s Gate reservoir and dam downstream.

2.5.5

Develop re-vegetation programs and BMPs where appropriate to reduce erosion.

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Restoration Goal 3:  Restore, Protect and Augment Habitat Quality, Quantity and Connectivity

 

3.1

Restore and protect missing linkages of fragmented habitat.

3.1.1

Allow Rainbow Trout / Steelhead passage from upper watershed to Glendale Narrows.

3.1.2

Provide and protect habitat corridors linking the San Gabriels to the Verdugos to the San Rafaels to Mt. Washington to Debs Park to Elysian Hills through smaller linkages between upland and lowland zones, and from habitat patches to waterways need to be established.

3.1.3

Enhance habitat linkages through the creation of new urban stream corridors.

3.1.4

Plant linear urban forest streetscapes for urban habitat connectivity.

3.1.5

Facilitate and monitor terrestrial habitat connectivity from San Gabriel Mountains to Santa Monica Mountains.

3.1.6

Facilitate and monitor wildlife movement among fragmented habitats of the watershed and the Arroyo Seco.

3.2

Integrate fire management into native vegetation zones.

3.2.1

Implement fire management techniques in urban interface zones.

3.2.2

Develop fire management strategy, especially in areas that have not experienced burns in over 30 years.

3.3

Restore, protect and augment terrestrial species habitat in existing open space of foothills and floodplains.

3.3.1

Protect and restore habitats, processes and ecological relationships supporting sensitive and endangered species, including arroyo toad, western pond turtle and other focal species.

3.3.2

Key species to target for restoration include Lesser Nighthawk, Greater Roadrunner, California Quail, Bobcat, and Gray Fox.

3.3.3

Promote watershed and habitat consciousness, and appropriate actions among residents, agencies and businesses in the watershed, including urban forestry, historic native plant distribution overlay.

3.4

Enhance and strengthen the urban interface zone.

3.4.1

Reduce negative effects of exotic plants and animals on native habitat.

3.4.2

Develop management guidelines for buffer and edge zones.

3.5

Restore and protect terrestrial species habitat in the riparian zone.

3.5.1

Naturalize stream and floodplain to provide viable riparian and aquatic niche opportunities while providing required level of flood hazard mitigation.

3.5.2

Restore native understory components of existing riparian and other woodlands.

3.5.3

Seek creation of new niche opportunities through biological storm water treatment systems and restoration of watershed-supporting native plant communities – combining habitat with water resource protection.

3.5.4

Restore and protect riparian vegetation communities such as alluvial fan sage scrub and sycamore-alder woodland.

3.5.5

Key species to target for restoration include the Arroyo Toad.

3.5.6

Develop exotic pest plant and animal management strategy for the watershed.

3.6

Restore aquatic species habitat.

3.6.1

Augment and restore missing species from endemic plant communities.

3.6.2

Key species to target for restoration include Southern Steelhead Trout.

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Restoration Goal 4:   Improve Recreational Opportunities and Enhance Open Space

 

4.1

Improve connectivity and public access from the Angeles National Forest to the coastal shore.

4.1.1

Improve the network of trails and open spaces with multi-modal trails.

4.1.2

Provide access for public use of the watershed’s rivers and streams.

4.2

Protect and interpret natural, community, cultural and historic resources.

4.2.1

Improve connectivity between parks, open space, cultural and historic resources through trails and land acquisition.

4.2.2

Develop trails that connect residents across communities to meaningful destinations.

4.3

Integrate natural resources management with recreational needs.

4.3.1

Manage parks and other open spaces, including golf courses, trail connections and native habitat to benefit flood management.

4.3.2

Provide opportunities for a range of recreational activities.

4.3.3

Coordinate between agencies and groups to meet community needs for recreation with agency priorities.

4.4

Protect existing open space while augmenting open space network.

4.4.1

Inventory existing and potential open spaces for protection, recreation, land use conversion.

4.4.2

Introduce the concept of long-term acquisition with an open public process.

4.5

Improve visual quality of the landscape.

4.5.1

Expand urban tree-planting programs.

4.6

Mediate conflicts between recreation and conservation and opposing recreational users.

4.6.1

Improve the cooperative spirit among recreational users through an open public process.

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