Kauai Mayor Bernard Carvalho’s rejection of a contentious bill that would restrict and monitor the use of pesticides by major agricultural and biotechnology companies should compel the state to move quickly into the void, whether or not the Kauai County Council overrides the mayor’s veto as expected.

Carvalho insists that he agrees with the intent of Bill 2491, which the Council approved 6-1 on Oct. 16 after a marathon hearing, but that a comprehensive legal review of the measure by the county attorney’s office made it clear to him that the county lacks the authority to enact the bill’s major elements.

Chief among his concerns: that existing federal and state laws may pre-empt the county from enforcing its own pesticide laws, that the measure may violate the state’s Right to Farm Act, and clearly violates the County Charter and usurps the mayor’s executive power by assigning new regulatory functions to the Office of Economic Development, an agency within the executive branch.

The bill’s supporters are outraged by the veto and accuse the mayor of caving in to pressure from biotechnology and agricultural companies that oppose it.

While many legal arguments have been floated by those opposing the measure, a coalition of environmental lawyers back the bill and say the threatened legal challenges are not insurmountable.

Defending the lawsuits would be expensive, though, and paid for by the taxpayers, a burden for the county that Carvalho would like to avoid.

Councilman Gary Hooser, who co-introduced the bill, promises that the veto will fall to an override, which requires five votes, and must occur within 30 days.

Threaded through Carvalho’s explanation of the veto is the core message that the state has a large role to play in regulating Hawaii agriculture, and he’s right about that.

The state Department of Agriculture is seeking funding to hire more agricultural inspectors on Kauai and is working with Syngenta Hawaii, Dupont Pioneer, BASF Corp., Dow AgroSciences and Kauai Coffee — the five companies affected by this bill — to develop voluntary guidelines for pesticide-use disclosure and the creation of no-spray buffer zones around schools and hospitals.

At this point, voluntary guidelines perceived as being devised by biotech and agribusiness are not going to cut it. Although the fight over the cultivation of genetically modified organism (GMO) crops and the large-scale use of restricted pesticides is most heated on Kauai, this is a statewide issue.

Carvalho’s veto rightly highlights that fact, and should add new urgency to the effort to craft statewide standards that require large enterprises to disclose pesticide use in a format easily accessible to, and understood by, the general public.

While a county’s authority to enact and enforce such requirements may be cloudy, the state’s authority to regulate pesticides is clear.

Given Carvalho’s veto, and his doubts about whether this county bill will withstand legal challenge if overridden, the state should exercise its power and make the best elements of the Kauai bill mandatory throughout Hawaii.