The following frequently asked questions were developed while the Lake Calavera Preserve Improvement Project was active from August 2016 to January 2017. They have not been updated since that time and are provided here for reference only.
What’s happening at Lake Calavera Preserve?
The Carlsbad City Council approved a contract in June 2016 for the first of two upcoming improvement projects to the Lake Calavera Preserve slated for this fall. The Lake Calavera Preserve is one of the city’s largest areas of protected habitat and nature trails, located in the northeastern part of Carlsbad. The first project includes the removal of invasive plant species, primarily non-native Mexican fan palm and Brazilian pepper trees, and then habitat restoration with native trees and plants. The second project includes the installation of a single-unit restroom with a drinking fountain and bike rack for preserve and trail visitors. Both projects will require some temporary trail closures this fall once work gets underway.
When will the improvements start, and how long will they take to complete?
Some minor prep work for the non-native palm grove removal took place this summer. It included the application of a glyphosate herbicide to the trees slated for removal. The balance of the work - including the actual tree removals - will begin on September 19 after the bird nesting season has concluded. All work will be completed by the end of December.
Will trails be affected during the improvements?
Intermittent trail closures are expected to allow for work near the project sites. Please stay on marked trails at all times and observe all posted signage during improvements.
How much is the city spending on these improvements?
Nearly $600,000 is being invested by the city for these improvements to this popular open space area.
Is the level of Lake Calavera lower because of these projects?
No. The water level in Lake Calavera is unrelated to these improvements. The lake was lowered through the reservoir’s valve system in advance of the predicted El Niño storm season. Because the predicted storms did not come to pass, the lake’s level remains lower than usual. Caution signs have been posted near specific areas of the lake’s edge to deter people from entering the mud flats.
The effects of invasive vegetation like the palm and pepper tree can have profound effects on native vegetation and wildlife while providing habitat for non-native species that prey upon native species, including those that are threatened or endangered. The dead and dried palm fronds also increase fire risk.
What prompted the timing of this removal?
The removal of palm and pepper trees is required by permits issued by the State of California as mitigation for native vegetation removed near the dam. This vegetation removal was necessary to allow the state to conduct safety inspections.
Will something be planted in place of the palm grove?
The site will be restored with native plants like the western sycamore, western cottonwood, coast live oak, California blackberry, red willow and Mexican elderberry.
How long will it take for the new plant material to become mature?
Sycamore and oak trees will become established in a relatively short order, but will take years to reach full height. Willow and cottonwood trees will grow faster. The willow trees should easily reach 20 feet within a few years.
How will the palm grove be removed?
Holes were drilled into the trees and glyphosate herbicide was injected to stop the trees’ uptake of water and to reduce their weight for removal in September. The foliage of the trees is now turning brown in response to the application. Once the trees have died, they will be cut down and removed from the site. At the request of the California Department of Fish and Wildlife, a few palms of the trees will not be removed in order to preserve nearby valuable native habitat. Instead, they will be cut down, then cut into smaller pieces and will remain on site. These remnants will not be visible from the trails. Removal work will begin on September 19 and will take five weeks to complete.
Why is herbicide being used, and is it safe?
The use of this Environmental Protection Agency-approved herbicide is a widely used product approved by the Environmental Protection Agency. It is largely comprised of a salt compound and is similar to what’s available at local home improvement stores for residential use. Only a few ounces will be injected into each tree. It will not be applied to the plant leaves or soil. More information about glyphosate can be found on this third-party website: http://npic.orst.edu/factsheets/glyphogen.html
Will there be particulate drift from the tree removal process?
The herbicide applied to the trees will have been metabolized by the time they are cut down; therefore, the concern of particulate drift is unwarranted. Further, particular drift is typically associated with aerial broadcasting of herbicide, not the drill/injection method used in this situation.
What will happen to wildlife living in the palm trees?
Wildlife will relocate to surrounding areas in the 256-acre Lake Calavera Preserve or other preserves nearby (Carlsbad Highlands Preserve and Robertson Ranch). All are managed properties. Biologists advise there will not be much (if any) native wildlife occupying the palms.
Is this the first time the city has done something like this at Lake Calavera Preserve?
No. Over the last nine years, the city has performed many maintenance activities and has several mitigation and restoration sites within the preserve. Each of these projects has improved the quality of the preserve for wildlife.
Where will the restroom be located, and what will it look like?
The single stall, unisex restroom will be located near the dam spillway. It will include a drinking fountain and a bike rack. The exterior will feature materials similar to what was used for the nearby pump station.
Why is the city adding a restroom to this open space?
Plans for a restroom were included in the trails master plan in 2005 after a comprehensive public input process. A restroom has long been one of the top items requested at this popular open space area.
When will the restroom open?
It is anticipated to open by the end of January.
How will the restroom be monitored?
The restroom building will be equipped with an exterior motion sensor light and will be locked overnight to help prevent vagrancy and vandalism. The restroom building will also be patrolled by the police on the same basis as other park facilities in Carlsbad.