Chico’s AquAlliance has joined a coalition of groups in a lawsuit on the Delta Plan, which sets out the groundwork for water tunnels around the delta.

“The Delta Reform Act gave the Delta Stewardship Council a historic opportunity to remedy 40 years of water policy failures,” a press release sent by the coalition Friday states.

“The council instead failed to use the best available science — biological or economic — and adopted a status quo program that fails to fix the Delta or the water supply problem.”

The group plans a press conference Monday to discuss the lawsuit details.

Members include AquAlliance (www.aqualliance.net), California Water Impact Network, California Sportfishing Protection Alliance, Restore the Delta, Friends of the River and the Center for Biological Diversity.

Northern California “plays a pivotal role because of the location, geography and focus on groundwater,” said AquAlliance Director Barbara Vlamis, who has been working on issues in the lawsuit for the past two years.

“Groundwater was not on the radar of the environmental community 10-15 years ago.”

After the droughts in the early ’90s, and drop in groundwater, “I and others started beating the drum on how important groundwater is up here.”

She’s been working to submit documents with colleagues, attending meetings and “emphasizing how important the hydrology is to not just this region, but the entire state.”

“You can’t ignore the source when you’re trying to fix the delta,” Vlamis said.

Also Friday the State Water Contractors announced a separate lawsuit against the Delta Plan.

The contractors (www.swc.org), represent landowners from the Bay Area to San Diego who receive water from the State Water Project, which originates at Lake Oroville.

Members include Kern County Water Agency and Metropolitan Water District of Southern California, among dozens of others.

The press release on that lawsuit states that the current Delta Plan “exceeds the legislature’s express grant of jurisdiction,” and “violates the California Environmental Quality Act.”

The plan would result in less water delivery from the delta through a concurrent Bay Delta Conservation Plan, but “fails to identify feasible replacement water sources, and it fails to analyze the many significant impacts of the plan that will occur outside of the Delta region,” the release states.

Reach Heather Hacking at 896-7758, hhacking@chicoer.com or on Twitter @HeatherHacking.