Late Night Visitors

First thing in the morning, our team of biologists head out to the Calaveras Dam Replacement Project construction site to inspect for animals that may have wandered onto the construction site overnight. The inspectors help to ensure that none of the rare and endangered species in the area end up in the path of the day’s construction activities. 

Sometimes they find critters that need to be taken off site to a safe place. In fact, to date, our environmental inspectors have relocated western pond turtles, Alameda whipsnakes, California tiger salamanders, and many other species to a nearby, safe habitat away from construction.

Other times they find evidence that something passed through, but didn't stick around. This last week, our inspectors found the paw print of a mountain lion at the edge of a water holding pond. Also known as a cougar, puma, or panther, mountain lions are solitary predators of other large mammals, such as deer and elk.  Males can weigh up to 200 pounds, while females could reach 140.

Glimpses of these creatures have been seen by project personnel, but thankfully, none of our biologists have encountered the feline while making their rounds. But it serves as a reminder that we are not alone out here in the watershed, and we must continue our vigilance to help protect the animals and plants in the Southern Alameda Creek Watershed while we continue with construction of this important water reliability project. 

We are Building a “Mini-Dam”...for the California Tiger Salamanders!

Prior to and during construction, the Calaveras Dam Replacement Project implements measures to avoid and minimize impacts to wildlife located in the Alameda Creek Watershed. 

Our Environmental team has taken proactive steps to protect and relocate the California tiger salamander (Ambystoma californiense) species since the start of the project.  The California tiger salamander (CTS) is an amphibian native to Northern California growing up to 8 inches long.  CTS have started to migrate at night from upland habitats to aquatic breeding sites, especially during the first major rainfall events of fall and early winter.

 California tiger salamander (Ambystoma californiense)

Wildlife exclusion fencing is strategically located along the boundaries of the construction work limits to deter wildlife from entering.  Also, water moistened buckets are placed in trenches between silt fences to catch the critters, which are later relocated to nearby ponds.

Just this week our approved biologist monitored berm repairs performed on a relocation pond for CTS.  The berm serves as a barrier which is positioned on the top of the pond, to reduce turbidity and maintain suitable conditions in the pond.  Permission was given by the California Department of Fish and Game to relocate 50 CTS to this location. 

As of today, 78 California tiger salamanders have been trapped and relocated to safer habitats away from project construction. With the repaired pond, we will be able to provide them a suitable and safe environment for breeding.

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org.

Repair work on Pond for California tiger salamander

Repair work on Pond for California tiger salamander

Photo of pond after work completed

Sustaining the Environment at the New Irvington Tunnel

The seismic upgrade and expedited delivery of the New Irvington Tunnel is crucial to maintaining a consistently reliable, high-quality water supply for 2.5 million Bay Area residents. Engineers and construction and mining professionals work daily to achieve this goal. The San Francisco Public Utilities Commission (SFPUC) is equally committed to remaining environmentally responsible, and is working in collaboration with environmental scientists to ensure the work is done in a timely manner and environmentally sustainable manner.

Before construction could begin at any of the three tunneling sites, the SFPUC took numerous measures to ensure that environmental impacts are kept to a minimum on the project sites. One measure used to protect wildlife is to install wildlife exclusion fencing around each of the work sites. The black 4-foot high fabric fencing deters wildlife from entering the construction sites and is monitored for its integrity on a weekly basis.


The fence won’t discourage all wildlife. For our winged neighbors, an environmental monitor scours work sites for any signs of nesting birds. Initially, monitors try to discourage birds from establishing nests on site. However, if they encounter a completed nest, construction zones are altered or activities are postponed in that area until all the nesting birds have fledged or left the nest.

Protections against erosion and storm water run-off are also required. On the exposed slopes at all three tunneling sites, workers laid down wattles ( which are woven netted tubes filled with straw) to help prevent soil erosion. Wattles are laid down perpendicular to the slope, and when combined with other practices (such as mulching), prevent or slow down the effects of stormwater runoff.

Mulch is also applied to the hillsides to prevent erosion, through both a process called hydro-mulching and by manual methods. Hydro-mulch, which consists of recycled natural fibers combined with a tackifying agent, is sprayed onto the hillside and coats the soil. Straw is also manually laid down onto the slope. To help the vegetation grow, seed is added to the mulch mixture and applied to the slope through a process called hydro-seeding. As the vegetation grows, the mulch decomposes into the soil and the vegetation itself stabilizes the slope and prevents rain from directly falling on the soil and producing erosion.


Finally, all three of the tunneling sites are monitored daily by SFPUC environmental inspectors and specialty monitors. They verify that workers are in compliance with the environmental standards set by the SFPUC and environmental permitting agencies to maintain a healthy environment!