It didn't take arcane alchemy or a purification plant to transform Palo Alto's groundwater from a construction nuisance into a precious resource.

All it took was a surge of civic engagement and intense lobbying from residents, many of whom packed into City Hall on Tuesday night to urge city leaders to put an end to "dewatering" -- the act of pumping out groundwater to enable basement construction. In 2016, the eight residential projects that entailed dewatering pumped out 140 million gallons of water, according to Public Works staff. Many in the community were offended by the sight of rivers flowing down gutters en route to the city's storm drain system.

On Tuesday, members the City Council added their voices and votes to the citizens movement when they approved new requirements for basement pumping. These include a new time limit for pumping (a two-week "startup" period followed by 10 weeks of pumping); new standards for fill stations at pumping sites; and a requirement that pumping go no deeper than 3 feet below the basement slab during the construction period and 1 foot after the slab is poured.

The council also signaled that greater changes may be on the way in 2018, when the city may start requiring basement builders to use cutoff walls, a construction technique that isolates the basement area from the broader site and drastically reduces the amount of water being pumped.

While the issue of groundwater pumping isn't new to Palo Alto, it has taken on renewed urgency over the last few years, thanks to a lingering drought and a growing number of construction projects. Dozens of residents, most of them wearing "Save Palo Alto's Groundwater" stickers, flocked to the council meeting Tuesday to urge action. Some called for a moratorium on groundwater pumping; others urged members to immediately require the more localized construction techniques.

Keith Bennett, founder of the citizens group, urged the council Tuesday to demand a greater contribution from builders who pump out water.

"Dewatering makes significant use of public resources, particularly groundwater and storm drains, by a few without compensation to the community who provide funding for these resources," Bennet told the council. "Impacts of private development on the larger community are an increasing angst for many residents -- not only for basement construction. We must not be afraid to require applicants to incur additional project costs to reduce impacts on the community."

Former Mayor Peter Drekmeier, a longtime conservationist, noted that one property had pumped out 30 million gallons of water last year. That amount of water, he said, has a market value of about $130,000.

"We all know water is very precious," Drekmeier said. "Unfortunately, the water pumped out of basements is considered to have no value because it's a nuisance. That's why we don't care for it."

Ester Negenda, who is also a leading organizer of the citizens movement, urged the council to think of the city's groundwater "as a resource, not a construction byproduct."

"It's time to work together to make sure we have a sustainable water future," Negenda said.

The council largely shared this sentiment. Vice Mayor Liz Kniss said there's "never been a time when we've been as aware of water flowing in a gush down the streets." The only question that stirred debate was: How far and how fast should the city go?

Councilwoman Karen Holman, joined by Lydia Kou and Tom DuBois, advocated for a more aggressive approach. Rather than wait until 2018 to impose the new cutoff-wall requirement, the city should consider adopting them for this year's construction season, which goes from April to October, Kou and Holman both argued.

"I think we've waited long enough and the residents have done a great deal of research on this," Kou said.

Holman agreed.

"We have plenty of data," she said, "We need to move on it. We need to act on it. We need to stop the waste."

Others were more cautious. Rather than requiring cutoff walls this year, the council supported giving incentives to builders to construct them. Chief of these is waiving the requirement for an enhanced geotechnical study for those who use the less wasteful technique (they would still have to perform a more rudimentary study).

After the proposal from Kou and Holman failed by a 3-6 vote, with DuBois joining them, the council unanimously approved the gradual approach, which Mayor Greg Scharff called "a good compromise."

"I think it's a good vision and I think it's a sustainable vision," Scharff said.