Consultant Lisa Maddaus answers questions about drought and water availability data in the water supply assessment for the Rancho Murieta North Project.
Development took center stage at the Community Services District last week with a public meeting on a water supply report that concludes there is enough water for 827 new residential lots proposed for Rancho Murieta North. Some audience members challenged the report’s conclusions and data.
At the meeting, CSD General Manager Darlene Gillum explained the report was done at the request of Sacramento County. “The primary purpose of the water supply assessment is to determine if the water agency’s supply is sufficient to serve the proposed development under a normal year, single dry year and multiple-dry-year conditions during a 20-year projection,” Gillum told the audience of about 18 people. The assessment covers the next two decades, to 2035. It includes a development schedule, lot sizes and the total number of lots, as well as an overview of CSD water operations.
The CSD diverts water from the Cosumnes River, stores it in reservoirs, treats it and distributes it to CSD customers.
The report will be used in the California Environmental Quality Act analysis for the Rancho Murieta North project, which is going through the county planning process and would substantially complete the development of Murieta North.
Consultant Lisa Maddaus, of Maddaus Water Management Inc., prepared the report. It utilizes information from previous CSD water studies.
Gillum described the supply report as a conservative approach to water supply projections. Available water is limited to what is stored in the reservoirs and does not include water used during the diversion season or water from wells.
“The wells are not drilled. We don’t know for sure what the augmentation wells will actually provide for any additional supply,” she said. “So to keep things on a conservative basis, we did not include any augmentation well supply.” A supply of recycled water is included, however.
Currently the CSD supplies the Country Club with the wastewater it recycles. The club uses the water to irrigate the two golf courses, and additional recycled water is needed to fully supply the club’s needs. As the amount of wastewater increases with development, there will be enough recycled water to meet the club’s needs, plus an additional amount that can be used to offset the demand for potable water.
Gillum said 560 acre feet of recycled water is included in the water supply assessment as the amount that will be available in the future to offset potable water use. The number was derived from the 2006 Integrated Water Master Plan, Gillum said, by subtracting the 550 acre feet the Country Club needs for the golf courses from the total amount of recycled water estimated to be available with growth. According to the water supply report, additional recycled water is not expected to offset potable water use until 2030-2035.
Gillum emphasized that while water supply assumptions are constrained in the assessment, water demand assumptions for the proposed developments are not. “We didn’t try to constrain the estimated demands ... we wanted to see where it would go,” Gillum said. “We wanted to build it up, again being more conservative on the demand side.” Indoor water use in the report is “about 61 gallons per day per capita,” she said. “We estimated there would be three people on average per lot per house. That’s a higher number than what the census shows. Typically we run about 2.3 people.” Irrigation demands are calculated for the proposed lots and park land. “It’s projecting a larger demand than is probably going to happen in reality,” Gillum said.
President Jerry Pasek remarked that “outdoor irrigation is becoming less and less of a water hog. ... Leading to 2014, most of our water went to irrigation, so when we got a water shortage or a drought condition, that was a place where we saved.” According to Pasek, outdoor water use accounts for 70 percent of water use in the district. The role landscape irrigation plays was apparent in the 2013 CSD water use study based on customer billing from 1998 through 2012, where two-story houses on larger lots emerged as major water users.
The water supply assessment will undergo peer review at the county, and eventually become an attachment to the environmental impact report for the development project, Gillum said.
More than half a dozen audience members commented on the water supply report. Some expressed concerns about groundwater depletion if CSD installed wells for emergency use, the need for a glossary of water terms and explanations of the water calculations, and the potential for multi-year droughts caused by climate change.
“The drought projections are all based on our ‘75-’76 or ‘76-’77 driest year, but there’s no effort to see if that driest year is what experts are predicting for the future of California,” said Linda Klein of Save Our Lakes & Open Spaces, a group formed in opposition to the proposed development plan. “There are predictions by scientists that drought conditions perhaps would be more extensive than they have been in the past.”
Consultant Lisa Maddaus responded that an earlier CSD study modeled worst case scenarios at various development levels and employed climate-change analysis. “The assumptions still hold. ... Your worst case hydrology, the ‘76-’77, is still worst case,” she said. “In ‘77, you could not pump at all.”
Gillum observed that the latest drought “did not impact us the way it impacted the rest of the state. ... ‘76-’77 is the worst it’s been for us.”
The district had a close call in 2014, when Maddaus was called on to evaluate the possibility that river flows wouldn’t allow diversions. But rain arrived in February that year to raise river flows, and the reservoirs were filled.
“You’ve got to keep in mind that we’re dependent on river flows, not annual rainfall or anything else that they talk about,” Pasek told Klein. “Two good rainstorms get the river flowing for 30 days plus and we fill the reservoirs.”
Klein continued the dialogue in the RanchoMurieta.com forums a few days later.
Cheryl McElhany, head of SOLOS and a Rancho Murieta Association director, characterized the CSD water emergency plan as a choice between 50 percent water conservation or using wells to augment the water supply. Why wasn’t a reduction in households considered as a way to safeguard the water supply? she asked.
“It’s an alternative, but I’m not sure I know too many people who would support it,” Parek replied when McElhany pressed for a response.
The water supply assessment is available here.