Salinas >> With seawater continuing to seep deeper in the Salinas Valley groundwater basin and threaten a deeper aquifer that helps feed municipal and agricultural uses, Monterey County officials are poised to consider a formal plan of action including a proposed moratorium on new wells in the area after months of discussions.

On Tuesday, a joint meeting of the Board of Supervisors and the county Water Resources Agency board are set to consider new groundwater maps showing seawater intrusion is continuing its “vertical migration,” and a final report and recommendations from a working group on how to respond to the worsening situation.

The meeting is set for the supervisors’ afternoon session starting at 1:30 p.m. at the County Government Center in Salinas.

Water agency senior hydrologist Howard Franklin said new northern Salinas Valley groundwater maps using 2017 groundwater wells data shows “islands” of seawater intrusion are still growing, indicating that salt water is continuing to leak from the 180-foot aquifer into the 400-foot aquifer, and is now the “dominant mechanism” for seawater intrusion in the area. Franklin blamed groundwater users “going deeper for water,” including drilling even beyond 400 feet into the constrained deep aquifer, for their supply.

In October, the water agency produced a report based on 2015 data that showed vertical migration of seawater intrusion into the 400-foot aquifer, and recommended an immediate halt to new wells and other measures. But county supervisors decided to spend six months taking a closer look at the issue and potential measures to address the problem, and the more recent data has been analyzed showing the trend is continuing in the meantime.

At the same time, Franklin said the new maps show the “contiguous front” of seawater intrusion has slowed considerably since speeding up two years ago, probably in response to the drought and a three-year hiatus in operation of the Salinas Valley Water Project that required the increased use of groundwater wells instead of treated river water for farmland irrigation.

Meanwhile, the 90-day working group’s report offers a series of immediate, short-term and longer-term actions over the next two to 20 years designed to address the saltwater advance. Most of the recommendations mirror the water agency’s own advice with a few tweaks.

According to a staff report, the group’s recommendations are aimed at producing a “comprehensive solution intended to protect public health and drinking water quality” from the seawater intrusion threat, while preserving agricultural production and economics, and noting the impending development of a state-mandated groundwater sustainability plan for the entire Salinas Valley basin due in the next two to four years.

First, the group calls for the county to enact an immediate moratorium on new wells in the 180-foot and 400-foot aquifers in a finalized “area of impact” most affected by the trend, though it also suggests allowing replacement wells to be drilled and exempts domestic, municipal and monitoring wells.

The group also recommends the county devote $1 million in emergency funding to begin destroying dozens of abandoned, leaking wells blamed for facilitating the deeper saltwater migration, starting with eight of the worst wells identified as urgent priority within three to six months. The county would also develop a program for destroying all of the 142 abandoned wells in the area.

In addition, the group advises spending up to $1.5 million on an investigation of the capacity of the deep aquifer, where an increasing number of landowners have begun drilling in search of fresh water, and minimize well drilling until that study is complete. Replacement wells could be allowed under the condition that landowners must meter their groundwater extractions, and monitor levels and quality, while agreeing to provide that data to the agency.

At the same time, the group calls for optimizing and enhancing the Castroville Seawater Intrusion Project, which provides recycled water and treated river water for farmland irrigation, while developing an annexation plan aimed at expanding the project’s area of service.

Over the longer term, the group calls for destroying the remaining abandoned wells at a total cost of about $7 million, completing the Castroville project expansion, and ending all pumping in the 180-foot and 400-foot aquifers in the area with the exception of Castroville project supplemental wells, and domestic, municipal and monitoring wells.

While the group considered extending the new wells moratorium to domestic and municipal wells, it opined that general plans and land use policies would supercede such an effort, but advised pursuing land use policy changes in the future and near-term incentives aimed at reducing all groundwater pumping and increasing irrigation efficiencies.

Jim Johnson can be reached at 831-726-4348.