SANTA CRUZ >> Some 10 months after it began meeting, the city Water Supply Advisory Committee has begun to dig into the “meat and potatoes” of its mission, said Santa Cruz Water Director Rosemary Menard.

Looking at consultant- and city-produced projections that build off historical water usage data, Santa Cruz could face as much as 68 percent water shortages during its peak demand months in its driest years by 2020, the water committee was told at its meeting Thursday.

“In the driest years, under either proposal, significant shortages are estimated,” consultant Gary Fiske said.

Fiske pointed to the impact of ongoing negotiations over fish habitat in the San Lorenzo River and North Coast streams as significantly affecting city water supplies. The outcome of city negotiations with state and federal regulators will likely result in reduced water usage access.

“They’re starting to move on from a lot of learning and getting their arms around the issue to something more concrete,” Menard said Thursday.

The 14-member committee was appointed by the Santa Cruz City Council and tasked with coming back by October with recommendations designed to help ensure a sufficient city water supply into the future.

This week, the committee began to draft a base-line assumption about the city’s expected demand going into the future. From there, the committee will be able to tweak the projections with future complications, such as climate change, and see what will be needed to conserve, produce and/or store more water.

Some members of the two dozen audience members attending the meeting urged the committee consider making their water use assumptions based on the water supply available, rather than trying to meet the need of a higher demand. Speaker John Aird said it would at least be useful for the committee to consider including a reduced-water usage scenario in their planning, “to see what we have to give up to achieve it.”

Consultant Fiske said he believed the projections should not included reduced water usage assumptions because that would disguise part of the issue from the public and city policy makers.

Thursday’s and Friday’s meetings came after a public water policy forum Wednesday night at the Santa Cruz Museum to hear from experts on big-picture energy and water conservation concepts and a look at the economic impact of water rationing.

Economist David Mitchell said a look at Santa Cruz County businesses in 2013 showed that water restrictions notably affected local nurseries and garden center, landscape contractors, golf courses and the hospitality industry, particularly restaurants. The agriculture industry took the hardest hit, though, Mitchell said.

“Agriculture is the most vulnerable to water shortages. Ag is the one that has the cross hairs on it,” Mitchell told the audience. “Counties like Santa Cruz County are doubly affected, with the urban and ag both affected. You can end up in a situation where they both get whacked.”

Rosenblum looked at the benefit of water and energy conservation as a way to reduce long-term capital investments in the water system. Cities that have succeeded in mandatory efforts to reduce water usage have created a comprehensive strategy to market an energy efficient technology program, Rosenblum said.

A successful energy reduction plan would include drought-resistant landscaping, well-marketed water and energy conservation technology packages for the public and high consumer buy-in, Rosenblum said.

The Water Advisory Committee will continue its meeting with a second session Friday, beginning at 2 p.m. at the Santa Cruz Police Department’s community room, 155 Center St.