Natural Treatment Site: Old Laguna

Old Laguna NTS site

Old Laguna NTS site has functioned well throughout this year.  It was taken offline only twice to facilitate repairs to the outlet structure and clear vegetation.  There have been no problems with sulfides, however, algal growth in the slow-moving pools continues to be a problem, but not enough to warrant drainage of the site.

Water quality monitoring at the site has shown good removal rates for all nutrients including nitrogen and phosphate; suspended solids and total coliform removals were adequate as well. Selenium removal rates were within the standard range.  

The site is scheduled for maintenance upgrades next fiscal year, including sediment removal near the inflow pool. Went online February 2006.

 Location & Size

ocation: 16585.5 Laguna Canyon Road, Irvine
Size: 2.5 acres
Tributary Watershed: 231 acres

  Biological Values

he site is somewhat isolated, and wildlife values are low.  Additionally, African Clawed Frogs were discovered at the site this year, which may warrant further action, such as draining the site to facilitate removal. The following nesting bird species were observed on the site: Marsh Wren, Bewick’s Wren, House Wren, Mallard, Western Bluebird, House Finch, Black Phoebe, Tree Swallow, Common Yellowthroat, Song Sparrow, American Crow, Greater Roadrunner, Yellow Warbler, Mourning Dove, Yellow-breasted Chat, American Coot, Bullock’s Oriole, Ash-throated Flycatcher, American Robin, Cooper’s Hawk, Red-shouldered Hawk. Additional wildlife observations are planned for next year’s report.  


Routine Maintenance Activities:

    • TruGreen LandCare provides routine irrigation and landscape maintenance services at the site. Additional work such as mulch replacement, irrigation repairs, aquatic herbicide application, aquatic vegetation removal, and sediment removal were performed throughout the year.
    • System operations staff performed weekly site inspection, water quality monitoring, and landscape and irrigation maintenance review.

Major Repairs: The slope along Laguna Canyon Road (which the City of Irvine maintains an easement upon) was excavated in part to install a manhole for a fiber optic cable.  Sediment removal at this site is planned.