Recommended Machado Lake Plan

Habitat and Park Design
An intensive program of invasive removal will take place throughout KMHRP. Invasive species like Ludwigia will be removed, while the Southern Tarplant and the Coastal Sage Scrub will be enhanced to satisfy habitat enhancement opportunities. Construction of park improvements including smart irrigation, new trails, and site amenities, such as fishing piers, are also recommended. Lake edge treatments, or planted bioinfiltration areas, will be constructed. These buffers will be designed and constructed to encourage pedestrians to utilize the park trails and designated access points to walk to the lake shoreline and to intercept irrigation runoff before it enters the lake. Schematics of the lake edge treatment concepts are shown at right.

BMPs were evaluated for each of the major storm drain outfalls to remove trash and sediment from runoff before discharging to Machado Lake or the Freshwater Marsh. BMPs include Continuous Deflection Separation (CDS®) units at storm drain D24010 and at the Figueroa Drain; a Gross Solid Removal Device (GSRD) at Project 77; a bioengineered vegetative swale for dry weather treatment at Project 77; and a bioengineered vegetative swale at Project 510 Line C. The golf course maintenance yard will contain site BMPs.

Lake Options
The full suite of lake rehabilitation options will be implemented in the recommended alternative. This includes lake dredging and lake augmentation with supplemental water. Recycled water from the Terminal Island Water Reclamation Plant will be used for lake augmentation, while potable water will be used as a backup supply. Both these measures are needed to achieve and maintain a lake depth of approximately 8 feet, which is important in order to minimize internal nutrient loading. Dredging the lake will also remove sediment that is currently overenriched with nutrients and contributes to the internal nutrient loading problem. An offline-treatment wetland, an aeration system, and alum injection (as necessary) will also help satisfy the water quality objectives by removing nutrients from the water and increasing dissolved oxygen. In-lake sediment basins will be constructed in the northern portion of the lake just south of the riparian forest and near the Project 77 storm drain outfall to promote localized sediment deposition. The dam at the southern end of the lake will also be modified so that the lake level can be adjusted as desired. A final decision with regard to floating versus terrestrial islands will be made during the design phase.

In addition to the offline treatment wetland adjacent to the lake, wetlands improvements will be made in both the riparian woodland and lower freshwater marsh. Riparian woodland improvements include a runoff capture area and secondary flow channel. In the lower freshwater marsh, various methods will be used to increase flow dispersal, including a series of swales and berms at Storm Drain D7223. In addition, three acres of new emergent wetlands will be created.

Machado Lake
Recommended alternative
Conceptual illustrative Sections of Machado Lake Rehabilitation

Machado Lake Recommended Plan Performance Measure Results
Project Goal Performance Measure Result
Satisfy water quality objectives -Reduce sediment load to Machado Lake
-Reduce wet weather metals load to Los Angeles Harbor from stormwater BMPs
-Reduce mean summer phosphorus
-Reduce mean summer nitrogen
-Reduce mean summer chlorophyll-a
-510 tons removed per year
-222 pounds removed per year

-63% reduction from baseline
-53% reduction from baseline
-71% reduction from baseline
Enhance recreational opportunities -Provision of amenities
-Length of new trails
-2,370 feet
Provide a sustainable project -Probability of meeting TMDL
-Supplemental water requirement
-Recycled water use
-Reuse of dredged material
-5 (rated from low [1] to high [5])
-115 acre feet per year
-10% of total excavation
Enhance habitat -New wetland habitat
-New upland habitat
-Invasive plant removal - primrose
-Invasive plant removal - Cal-IPC non-natives and other non-native threats
-7 acres
-5.4 acres
-5.9 acres removed
-11.5 acres removed
Achieve cost efficiency -Estimated capital cost
-Estimated annual operation and maintenance cost
-$70.2 million
Minimize short-term construction impacts -Dredged material removal requirement -11,250 bins of dredged material

Project Schedule

Construction will begin Summer of 2012.

If you have questions or comments, please call the outreach coordinator at (213) 978-0317. The project description, concepts and design are preliminary and subject to change.