The Colusa Groundwater Authority this past month has taken their first groundwater report on the road.
Authority officials have given multiple presentations to public agencies and stakeholders in Colusa, Williams, Maxwell and Arbuckle. The report, which the California Department of Water Resources will require annually, provides an overview of local groundwater conditions and the Colusa Subbasin Groundwater Sustainability Plan.
CGA Chairwoman Denise Carter said the Groundwater Sustainability Plan, which is presently under a review by the State, is a joint document of the Colusa and Glenn groundwater agencies that describes how the two agencies will reach long term groundwater sustainability by outlining the need to reduce overdraft conditions and by identifying projects that may replace or supplement groundwater supplies to meet current and future water demands.
“We’ve developed one plan between the two counties,” Carter said. “The plan was submitted at the end of January. It took consultants and board members interaction and review over the past three years to put this plan together.”
Carter said DWR has up to two years to review the plan, which she said is a dynamic planning document that will guide how groundwater will be managed over the next 40 years.
“The plan is meant to be revised as needed,” she said. “It is required to be updated every five years. Groundwater conditions don’t change overnight, so you have to look for major trends.”
Because the plan has been submitted to the state for review, the groundwater authority has begun to implement the plan by monitoring groundwater levels, measuring land subsidence, and developing a well-monitoring program of 48 sites between the two counties.
The GSA also established 63 sites to establish benchmarks for land subsidence, which is a gradual settling or sudden sinking of the earth’s surface, often caused by aquifer-system compaction and the overpumping of groundwater during droughts.
Carter said the DWR is also measuring ground subsidence with interferometric synthetic aperture radar (InSAR), with data made available to the GSA every three months.
Although most of the local area appears to be in fairly good shape, Carter said subsidence is occurring in the Arubuckle and Orland areas.
“One of our biggest concerns is the impact it has on adjacent infrastructure,” Carter said.
The report also provides information on historical groundwater conditions. Between 1990 and 2015, measurements show that when dry conditions occur, groundwater levels diminish because groundwater is replenished by rain and surface water.
While the region sits over a somewhat healthy but unmeasurable aquifer that could range from 26 million acre-feet to 140 million acre-feet, the purpose of the Groundwater Sustainability Plan is to achieve and maintain groundwater for the survival of humans, wildlife, the environment, and food production, especially when ongoing drought taxes both surface and groundwater systems.
The GSA outlines about 34 projects and management actions, both planned and ongoing, to achieve sustainability, including actions to help recharge groundwater in the Colusa Subbasin.
“The uncertain future really calls for an adaptive management approach,” Carter said.
Carter encourages public agencies and stakeholders to remain involved with the groundwater sustainability process.
Williams City Councilman Sajit Singh, one of several local officials to participate in groundwater management activities, said the process and plan the groundwater authorities have engaged in and prepared is intense.
“I’m also very thankful the CGA and the GCA came together, too, for one Subbasin,” Singh said. “It’s a very impressive piece of work and there are some brilliant minds working on it.” ■