Wastewater agencies are playing a crucial role in shaping a sustainable water future by increasingly reusing highly treated water. Since the 1980s, the use of recycled water in California has nearly tripled, highlighting its growing importance in addressing the water needs of an expanding population.
Governor Newsom’s August 2022 Water Supply Strategy sets ambitious targets for the recycling of water, aiming to recycle at least 800,000 acre-feet per year by 2030 and 1.8 million acre-feet by 2040. This vision primarily involves redirecting wastewater that would otherwise be discharged into oceans. The November 6 State Water Resources Control Board meeting included a presentation of the numbers for recycled water production and use for 2023 and the progress the state has made towards achieving the ambitous goals. Rebecca Greenwood, an engineering geologist with the Recycled Water unit in the Division of Water Quality, provided the update.
Although volumetric data for recycled water has been collected intermittently since the 1970s, the 2019 Recycled Water Policy included a requirement to report influent, effluent, and recycled water use as appropriate for wastewater treatment plants and recycled water producers across the state. Now in its 5th year, there is a 98% compliance rate for reporting across all years.
With five years of data now available, the relationship between annual precipitation and volumetric data is emerging. Specifically, in wet years, recycled water production is lower. Staff attributes the decrease to increased inflow and infiltration of stormwater and groundwater into treatment and collection systems.
“So what we have here is a little bit of a switch,” said Ms. Greenwood. “We didn’t technically lose any groundwater recharge. We just were not recharging groundwater with recycled water; we were recharging groundwater with stormwater.”
With less effluent available on average in dry years, you might think there would be less reuse occurring, but that seems different from what’s happening, said Ms. Greenwood. The graphic shows the different discharge categories, including recycled water use, with the percentages representing the percent of total volume.
“Looking in terms of percentages, effluent is dominated largely, no matter if it is a wet or a dry year, by ocean discharges, so a lot of our treated wastewater is going into the ocean,” said Ms. Greenwood. “But what we want to highlight is recycled water, shown in the purple color; in drier years such as 2020, 2021, and 2022, the reuse of recycled water is a lot higher than compared to wet years such as 2019 and 2023.”
So the upshot is that even while investment in recycled water may be consistent, the growth may not be linear year over year; however, she said recycled water remains especially important in dry and critically dry years.
The Water Supply Strategy set a goal to recycle 800,000 acre-feet per year by 2030 and 1.8 MAF by 2040, focusing on redirecting wastewater discharged to the ocean to recycling. Ms. Greenwood noted that if they were able to utilize all the water currently being released to the ocean, it would not achieve the 2040 goal of 2.5 MAF of recycled water use.
“At this point, we’re projecting that we are on the path to meet our 2030 goal of 800,000 acre-feet, but it really will require additional investments and project planning to meet our 2040 goal,” said Ms. Greenwood. “The State Board will continue to work to achieve the state’s recycled water goals and support recycled water projects. We’ll work on that by identifying and resolving permitting and funding barriers; expanding our portfolio of recycled water projects by implementing direct potable reuse; and funding and research to advance the use of recycled water across the state.”
