On Friday, the U.S. Supreme Court will evaluate two appeals filed by California water agencies and a coalition of Central Valley farmers that urge the court to strip away strict regulations regarding agricultural and commercial water deliveries under the Endangered Species Act (ESA).

The two groups argue that under ESA protections afforded to the threatened delta smelt fish, critical water deliveries to parts of the state have plummeted by up to 30 percent per year, according to the Los Angeles Times. Environmental advocates say the water is needed to protect the delta smelt from extinction.

In October, a group representing San Joaquin Valley nut growers filed an appeal with the Supreme Court, urging them to reverse the delta smelt “biological opinion,” or “BiOp,” previously upheld by the Ninth U.S. Circuit Court of Appeals. The “BiOp” is the piece of legislation that mandates the water cutbacks under the ESA.

In the decision upholding the BiOp, Judge Jay Bybee wrote that economic factors and the legislation’s effect on third parties does not change the responsibility of the Fish and Wildlife Service to protect endangered species.

“The delta smelt has teetered on the brink of extinction…and the FWS has a duty to protect the viability of the smelt whatever the cost,” the judge wrote, according to the Times.

“We are asking the court to make sure the ‘whatever the cost’ language no longer applies,” Pacific Legal Foundation Director of Litigation James Burling told Breitbart News. Burling said he was “cautiously optimistic” the court would agree to hear the case, because it represents a “big case in terms of how the Endangered Species Act should be implemented.”

The Metropolitan Water District of Southern California filed their own appeal with the Supreme Court. A lawyer for the group reportedly argued in the appeal that the amount of water withheld during the winter of 2012-2013 “would have been enough to supply the entire San Diego region this year.”

In October, Kern County Agricultural Commissioner Ruben Arroyo explained to Breitbart News how reduced water deliveries affected agriculture and the economy in the Central Valley and the rest of the country.

“What’s changed now is that, let’s say a farmer has 100 acres of land,” Arroyo said. “Instead of asking, ‘What will I plant on 100 acres?’ the question now is, ‘How many acres of water am I going to get and which crops can be grown using the least amount of water?'”

“People might see $10 lettuce at the grocery store in a few years,” Arroyo added. “And all we’re going to be able to say is, ‘Sorry, but we don’t grow lettuce here anymore.'”

Opposing the water districts and nut growers are the National Resources Defense Council and U.S. Solicitor Gen. Donald Verrilli Jr.

“The underlying problem in California is that our demand for water consistently exceeds our supply, even in non-drought years,” NRDC attorney Kate Poole told the Times. “Wiping out our native fisheries will not solve this problem.”

Poole added in the report that water agencies have “a long history of exaggerating the impacts” of the protection of endangered fish species.

“I’m not exactly sure what the water agencies have said, but the effects on agriculture can clearly be seen from Fresno County to Kern County along Interstate 5,” Arroyo told Breitbart News on Thursday. “In Kern County, fields were left unplanted, trees removed, and wells went dry. So I can’t imagine what could be considered ‘exaggerating’ when there is clearly plain sight evidence regarding the lack of water.”