NID tries to predict change in water supply, demand for next 20 years
The Nevada Irrigation District has reviewed the projected supply and demand of drinking and irrigation water to over 25,000 homes, farms and businesses within its boundaries — a move needed to update its Urban Water Management Plan.
As a supplier servicing over 3,000 customers with over 3,000 acre feet of water annually, NID is required by the California Department of Water Resources to submit an Urban Water Management Plan once every five years. The plan offers an overview of the district’s water availability and reliability, estimates of past, present and projected water use, and strategies for meeting the community’s changing water needs.
Jim Crowley of Zanjero, the consultant company responsible for designing the district’s plan, discussed the scope of the issue during Wednesday’s NID meeting. Crowley said the plan has a 20-year horizon that demands that the district consider changes to the climate, community demographics and identity.
Crowley said treated retail customer trends over the last six years indicate a marked increase in connections to single-family homes and “other,” the customer classification use for standby fire services. The number of connections to industrial, commercial and government accounts, along with multifamily homes, has remained steady.
The district met the demand to provide their connections with 161,678 acre feet of water in 2020. By 2040, the plan predicted customer water needs increasing to 174,782 to 217,950 acre feet.
NID supposedly has access to 450,000 acre feet of watershed runoff and storage per year, Crowley said, but less is actually available “due to temporal differences between rights, demand patterns and storage strategies.” Additionally, capacity is potentially increased by the 54,361 acre feet of water the district can purchase from PG&E each year.
The plan requires districts to consider options in case of a drought once every five years, and in the case of a five-year drought.
Crowley said water supply is significantly impacted by short, extreme events. Longer drought events afford opportunity to “adjust strategies,” “decrease demand” and “increase carryover opportunities.”
Division 5 Director Rich Johansen said he would like to see more accountability efforts in the area to discourage violations of the drought irrigation constraints, which limits watering to before 10 a.m. or after 9 p.m.
“We should investigate impact mitigation effectiveness,“ Johansen said.
Crowley said the supply and demand forecast is based off the change in demand over the last few years, as opposed to anticipated population growth.
“Projections did not use county’s projected population growth,” Crowley said. “They are based on the six to seven years previous. It has nothing to do with making adjustments in demand, it’s the number based on previous (consumption), including Placer County.”
The consultant company Zanjero chose this method because of the challenges posed to calculating population growth, not just in Nevada County, but unincorporated parts of Placer County as well.
“For our situation it made much more sense to project future demand numbers based on historical actuals than population,” Crowley said.
Rebecca O’Neil is a staff writer with The Union. She can be reached at email@example.com
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