Los Osos is pushing its recycled water to schools, parks, and farmers



The long-awaited Los Osos sewer plant is up and running, with 95 percent of the affected properties hooked up as of Feb. 1, according to San Luis Obispo County officials.

Each day, an average of 446,371 gallons of wastewater is flowing to the plant, which means it's no longer going into the septic tanks that polluted the underlying groundwater for decades.

NO GROUNDWATER, NO PROBLEM A portion of the recycled water generated by the Los Osos sewer will be sold and delivered to properties with poor groundwater for crop irrigation, like this one on Blue Heron View Lane. - PHOTO BY JAYSON MELLOM
  • Photo By Jayson Mellom
  • NO GROUNDWATER, NO PROBLEM A portion of the recycled water generated by the Los Osos sewer will be sold and delivered to properties with poor groundwater for crop irrigation, like this one on Blue Heron View Lane.

While the high percentage of sewer connections marks an important step to solving Los Osos' water woes, the next challenge for the community is in effectively deploying the recycled water the plant generates, a resource that's supposed to play a critical role in the long-term stability of the Los Osos Valley Groundwater Basin.

For this story, New Times tracked down the details of where all of that recycled water is headed and for what purpose. Some elements of the program meet the expectations of a court-approved Los Osos Basin Management Plan, while others may be falling short.

Basin recharge

As a condition of approval for the Los Osos wastewater plant, the California Coastal Commission required that all the recycled water be "reinvested" into the Los Osos basin area.

Most of the 500 acre-feet (there are 325,851 gallons of water per acre foot) of recycled water produced each year will be sent to one location in that area: an 8-acre leach field off Broderson Avenue. Once disposed at the leach field, the water will slowly seep into the underground basin's upper and lower aquifers.

Both aquifers have serious ailments: The upper is plagued with high concentrations of nitrates (due to the septic systems) while the lower is experiencing seawater intrusion as a result of overpumping and drought.

Over the long term, the Broderson leach field is expected to help maintain water levels in the basin.

"Hydrogeologic reports show that 22 percent [of the water at the Broderson leach field] will eventually migrate to the lower aquifer over several years," said Mark Hutchinson, deputy director of the SLO County Public Works Department. "The majority stays in the upper aquifer and eventually make its way to wetlands along the [Morro Bay] fringe."

A small percentage of the recycled water—33 acre-feet annually—will go to the Bayridge Estates leach field to benefit Willow Creek, and another potential basin recharge project is in the works for Los Osos Creek.

While basin recharge is the main element of the Los Osos recycled water program, there are also efforts aimed at reducing the community's demand for groundwater.

Thirsty crops

Farming over the Los Osos water basin accounts for 750 acre-feet of groundwater use per year—far more water than the sewer plant can produce in recycled water over the same time span.

While the sewer can't deliver that much water to agriculture, basin regulators assumed that some farmers would be interested in utilizing recycled water to irrigate their crops in lieu of groundwater, according to the Basin Management Plan. But, ultimately, the county couldn't find any takers.

Still, per the Coastal Commission permit, at least 10 percent of the recycled water is required to go to agriculture as a mitigation measure, since the plant itself was built on ag land, according to county officials.

To stay in compliance, the county entered into recycled water agreements with four area landowners who either had no wells or had poor groundwater conditions on their properties. The county will sell and deliver up to 81 acre-feet, or 16 percent of the annual recycled water, at $100 per acre foot to those parcels, which are all on the east end of town. The agreements run for 10 years, but after five years, either party can back out with six months' notice.

"It's not ideal," said Bruce Gibson, 2nd District SLO County supervisor representing Los Osos. "I absolutely would have rather struck deals with people who could help the basin."

One of the landowners buying recycled water, who asked to be anonymous for this story, said he was considering drilling a well on his property until "this option came up." He plans on leasing the land to a farmer who will make use of the recycled water.

Hutchinson noted that the ag agreements could be beneficial in that they could be "proof of concept" for other farmers skeptical about feeding their crops recycled water instead of groundwater.

Schools, Sea Pines, and construction

In addition to hammering out contracts with farmers, the county is also working with local water purveyors to deliver recycled water to Los Osos' schools, the community park, and the Sea Pines Golf Course for irrigation.

That would save the groundwater basin about 63 acre-feet of pumping per year, and keep the grass green at the park and Los Osos Middle School, Monarch Grove Elementary School, Baywood Elementary School, and Sunnyside Elementary. Providing water for the golf course would save another 25 to 35 acre-feet, according to the Basin Management Plan.

The county also intends to start a construction water program, where local contractors can pick up recycled water from the wastewater plant to use for on-site needs like dust control, as opposed to using potable water for those purposes.

Recycled water deliveries are expected to begin sometime this summer. Standing in the way of all of Los Osos' recycled water projects, other than the leach field deliveries, is Regional Water Quality Control Board approval for a recycled water permit. The local stakeholders also need to finalize the various contracts, and some additional piping is needed.

"There's a lot of paperwork and a little bit of plumbing," Hutchinson said.

In general, Hutchinson emphasized the importance of securing a variety of places to send the plant's recycled water, since it will always be generated.

"The wastewater never stops flowing in," Hutchinson said. "Having as many options, expanding your suite of options, is always important." Δ

Staff Writer Peter Johnson can be reached at


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