We’re so excited about the work that will begin this summer at Baldwin Lake and Tule Pond! After years of study and planning, the lake and pond will undergo a major restoration to improve water quality, restore habitat, and enhance stormwater management in the project area. The lake is our most endangered historic feature. This restoration project will take time to complete, and at times some areas of the garden may be temporarily restricted. We appreciate your support and patience. Here’s what you need to know.
The Lake Today
The lake is approximately 2.5 to 3 feet deep due to sediment and organic material accumulation. Since the dredging of the lake in the late 1880s to a depth of 12-15 feet, urban and stormwater runoff draining into the man-made pond upstream have contributed to soil contamination and deposition. Additionally, uncontrolled runoff during storm events and scouring from abrasive flows have led to erosion of the shore edge.
Both Baldwin Lake and Tule Pond will be dredged to remove the buildup of sediment and organic matter. This will be followed by installation of equipment to improve water quality, drainage, flood control and other elements. For full details of the project scope, click here.
This project is a collaborative effort by the Los Angeles County Flood Control District, the Los Angeles County Department of Parks and Recreation, and the Arboretum Foundation.
Restoration to Begin!
July 2026: Fencing will go up to enclose garden areas affected by the project.
September 2026: Dredging will begin and trucks
will be hauling out the sediment.
October 2027: Construction is expected to be completed.
What You Need To Know
• Work will not be conducted on weekends, holidays,
or red flag weather warning days.
• Best management practices are being followed to protect air quality.
• The Arboretum will remain open during the sediment removal. However, garden areas impacted may be restricted during construction hours. Safety measures will be implemented for garden visitors.
• Sediment hauling will take place Monday through Friday, from 7am to 4pm.
Frequently Asked Questions
Community
How will my experience inside the Arboretum be affected during construction?
The Arboretum will remain open to members and visitors during normal hours. Parking will be as usual in the Main and South parking lots. There will be full access to most areas of the garden, and most routes will remain open and clear throughout construction.
How will water be removed from the lake?
If necessary, dewatering will be managed using pumps and filtration equipment that remove water from the lake and pond so sediment can be safely excavated. The process uses temporary tanks, filters, and other treatment systems to ensure water is properly managed before discharge. Treated water will then be routed into the Arcadia Wash.
Will any trees be affected by the Baldwin Lake Restoration?
Yes. Many of the trees along the shoreline around Baldwin Lake are volunteer trees, started by self-planted seedlings that have grown and matured. These trees will be moved to restore the original rock wall along the lake shoreline.
What are the days and hours that construction will take place?
Construction is planned Monday through Friday from 7am to 4pm. No weekend or nighttime construction is currently planned.
How will access routes be managed to minimize disruption to visitors?
All construction staging and truck access will stay within designated areas away from main visitor paths, as much as possible. Clear signs and temporary barriers will help keep visitors safely separated from work zones.
How noisy might construction be?
Typical construction noise may be like loud yard equipment but is limited to weekday daytime hours. Noise will stay within construction boundaries with the aid of noise control measures.
Will there be any smell from the construction project?
Some brief odors may occur during active work but will be managed by the required mitigation controls. Any odors from equipment or exposed soil will be temporary, limited, and not expected to affect visitors or nearby homes.
Wildlife
What will happen to the fish in the lake? Will the lake be repopulated with fish?
Numerous fish, mainly carp, were captured and relocated to other water ponds on the premises, so at present, no fish remain in lake. Mosquito fish will be returned to the lake once construction has been completed to abate mosquito populations.
What about birds?
Birds will naturally vacate the lake during construction. A biologist will check for nests and protect any birds during construction. Waterfowl and migratory birds will return once the construction is completed, and water returns to the lake.
The turtles?
Much like the birds, turtles will also naturally vacate the lake during construction. Thankfully, there are other water sources for turtles from our forest ponds to turtle pond, to waterfall ponds and aquatic pools atop Tallac Knoll. Turtles will also benefit from a newly restored lake and return in due course once construction ends.
Membership
Will my favorite part of the garden be off limits?
That depends on what your favorite part of the garden is! Think of this as a time to explore, discover, and fall in love with new areas across our 127 acres. We will be highlighting and featuring them during construction to whet your appetite for discovery.
What happens to my membership?
Memberships will continue to be active during the restoration project as the gardens will remain open. With 127 acres, there is much to explore, and your support is essential to sustaining our Arboretum! Our goal is to ensure that as construction is completed, the entire garden is stunning. Membership and donor support are key and help to fund more than half of horticultural staff who care for our gardens, our rich educational programming, and care for our historic landmark buildings—all of which continue to need funding during construction. Thank you for your support.
Do I get an extension on my membership?
Memberships continue on the terms and duration the members joined under. Should a member have any concerns or require a special accommodation, please contact Ivonne Escobedo, our Membership Manager at 626.821.3233 or
ivonne.escobedo@arboretum.org. Your membership support is vital to our garden care, maintenance of our historic landmark buildings, and to sustain our programs, all of which will continue during construction.
Will there be extended summer hours?
Yes, beginning on April 1 to Labor Day (Monday) September 7, we are open until 7pm (6:30pm last entry).
Historic & Cultural Considerations
Will an archaeologist be present during construction to address any historical artifacts discovered?
Yes, there will be an archaeologist onsite for both the lake and pond. Any discovery will be documented, and then final ownership determination will be decided in consultation with Public Works, Department of Parks and Recreation, the consulting Tribe(s), and the qualified archaeologist.
Has there been communication with the native tribe groups about this project?
Yes, we have been in contact with appropriate native tribes; the two tribes, Gabrielino Tongva Indians of California and Gabrieleño Band of Mission Indians – Kizh Nation. There will be a tribal monitor from each Tribe, onsite for ground-disturbing activities. For detailed cultural resource protection measures, please see draft CEQA (California Environmental Quality Act) document located on the
Public Works Project website for further details.
Will the rocks and boulders from the historic wall be reused?
When possible, historic rocks and boulders will be salvaged and incorporated into the project to maintain the site’s character.
Construction & Design Details
I live in the neighborhood near the Arboretum. Will there be a lot of dust and noise during construction?
Any dust and noise will be mitigated through mandatory watering, covered trucks, and limited work hours. The CEQA analysis found these impacts to be less than significant with controls in place. Dust controls are designed to keep dust from traveling off‑site. If dust becomes a concern, residents can call the construction contact number that will be provided in advance notices. You may also email
BaldwinLakeTulePond@dpw.lacounty.gov on any dust concerns.
What methods will be used for sediment removal?
Sediment will be removed using standard excavation methods. After the lake and pond are drained and the sediment has dried, excavators and loaders will remove the material and load it into haul trucks for off‑site disposal in accordance with all regulatory requirements.
How many truck trips are expected per day?
Truck activity will vary by phase. On average, about 10 truck trips per hour are expected, with peak periods reaching approximately 100–130 truck trips per day during the main sediment‑hauling phase.
Is there a potential for hazardous materials at the construction site?
Any sediment contaminated with lead will be removed and taken to a proper hazardous‑waste facility, and the rest of the material that is non-hazardous and will be handled normally. The CEQA report found no danger to visitors, neighbors, drinking water, or air quality because all materials will be contained and managed under strict guidelines.
What is the anticipated construction schedule and major milestones?
Construction is expected to begin in July 2026 after permits are finalized and will continue through October 2027. Work will occur in phases, including site preparation, sediment removal, historic wall rehabilitation, habitat restoration, and final landscaping.
Questions?
Who should I contact regarding my question?
