Ponds at wastewater treatment plants are like magnets for birds and bird-watchers, especially those along the migration flyway in California’s Central Valley area.

Among them is the Clear Creek plant in Redding, along the Sacramento River, which serves as its receiving stream. A 93-acre portion of the property contains 10 ponds, each about 7 feet deep, that were process ponds when the plant was built in 1961. Since then, two upgrades and expansions have altered the use of the ponds — except for the birds’ purposes.

Destination for walks

“The ponds attract a large variety of resident and migrating birds each year,” says Troy Mitchell, wastewater utility supervisor. The ponds draw a fair number of birders, too, especially from members of the local National Audubon Society chapter. Large groups can visit as well. Each year, the Wintu Audubon Society includes the Clear Creek ponds as a destination for it Second Saturday Bird Walk.

These are often full-day events held at various locations on the second Saturday of each month. The Clear Creek plant has been noted by the society as one of the top five bird-watching destinations in its county.

During the latest upgrade and expansion that began in 2007 and upped the dry-weather design flow to 9.4 mgd and wet-weather flow to 40 mgd, the ponds were closed to the public because of safety concerns during construction. Not everyone was happy.

Big upgrade

The seven-phase plant upgrade included treatment improvements and wet-weather flow enhancements. New influent pumps, a toxic gas scrubber system, and a chemical feed and storage facility were added. Chlorine and sulfur dioxide equipment was rehabilitated, and a new biofilter system was installed for odor control.

Clarifiers, the headworks, pump stations and filters were renovated. A new blower building was constructed, aeration basins were rehabilitated for nitrification and denitrification, and one of the ponds was converted to a facultative sludge lagoon. Overall, 10 ponds are used for emergency water storage.

When construction ended in 2014, the bird-watchers were back and happy again. Once through the main gate, they park in a designated area, sign a release-of-liability form and are given the combination to a lock on the pond area access gate.  

Diverse visitors

Waterfowl such as American avocets, northern shovelers, Bullock’s orioles, greater yellowlegs and blue-winged teal are commonly seen in the ponds. One birder reported seeing 500 birds of 19 species in a single day. “There are lots of birds in and around the ponds, and they build their nests out there because we are right along the Sacramento River and in the flyway,” Mitchell says. “We see a lot of wildlife, too.”

Other than a 6-foot-wide gravel walkway around and between the ponds, there are no special viewing structures, park benches or picnic tables near the ponds. Beyond grass mowing and weed control, the site needs no special maintenance.

Mitchell is glad the birders are back and he and his staff welcome them, but safety is his greatest concern: “We have had people actually go into a sludge lagoon, and we can’t have that. It’s always got to be safety first.”