Environmentalists on P.E.I. are concerned legislation meant to protect Island waterways from the runoff from farm fields is too unclear to be effective.
Conservation groups want government to review those laws.
Their concern follows a recent court case in which buffer zone regulations were challenged for the first time.
"It was confusing to the courts," said Shawn Hill, executive director of the P.E.I. Watershed Alliance.
"If it's confusing to the courts, it's probably confusing to producers in the province as well."
The court case stemmed from a fish kill last summer. Two farmers were charged with buffer zone violations. One fought the charges, and, after a trial in Summerside this month, he won his case.
Court heard the farmer had no grass headlands, but he did have 30 metres of forest between his fields and the river.
In the view of prosecutors, the law required farmers to have grass headlands on all fields within 200 metres of waterways, in addition to any forest or buffer zones. But the court ruled they were wrong.
The Environmental Protection Act says either a grass headland or a buffer must be used, but does not require both.
Many farmers, such as Randall Neiuwhof in Rustico, have been using grass headlands whether there is a forest buffer or not.
He plants grass headlands on almost all his fields, which helps keep soil out of rivers.
"We think that it's important to look after the environment," said Nieuwhof. Conservationists say most farmers are using both headlands and other buffers close to waterways and believed it was the law. Environment Minister Janice Sherry is looking into it.
"I certainly have every confidence in the judicial system in Prince Edward Island but the situation has arisen and that sends us back to look at those [regulations] and see what we need to do," said Sherry.
Environment Canada is continuing to investigate last summer's fish kill. The federal government has a two-year window to lay charges.
Nieuwhof says the buffer-zone case won't change his farming practices. He said grass headlands are important, whether they're the law or not.