A bill aimed at making it easier for shoreline property owners to put up retaining walls may set a dangerous precedent and cause harm to Oahu’s beaches and other coastal areas, city planning officials and environmentalists say.

Bill 17, which will be heard by the City Council Zoning Committee at 9 a.m. Thursday, would allow a shoreline property owner to seek a minor shoreline structure permit in some circumstances from the city Department of Planning and Permitting instead of going through the more expensive and timely process of obtaining a shoreline setback variance that DPP officials now require.

But Robert Harris, Sierra Club Hawaii executive director, said the bill could drastically alter how the city decides what structures are allowed on Oahu’s shorelines.

"To do a variance, you have to meet the criteria and the city actually has to consider it and make a determination that a variance is permissible," Harris said. "What this bill is proposing to do is to say people are entitled to build these things unless the city comes along and says otherwise."

Council Chairman Ernie Martin said he introduced the bill to make it easier for property owners trying to control runoff and erosion.

"To apply for a variance is currently extremely costly and time-consuming," Martin said in an email. "It is a complicated legal process out of reach for many landowners, especially families on the Windward side who have experienced years of continuous erosion of their property."

Businessman and attorney Howard Green said planning officials told him he could not have an after-the-fact minor shoreline structure permit for two walls to help stave off erosion caused by rainwater that comes down a storm drain easement next to his property. Green estimated that requiring a variance costs at least $30,000 more. A shoreline variance requires a property owner to first obtain a "finding of no significant impact" from the state Office of Environmental Quality Control, which can come only after conducting a draft environmental assessment, he said.

Green, who said he helped Martin prepare the language in the bill, contends the law entitles him to obtain a minor shoreline structure permit as long as the walls do not interfere with drainage, tidal action and other beach processes; do not establish an artificial shoreline; do not block public views; and do not block public access.

"They have to accept retaining walls if they don’t violate the four standards" Green said. A DPP inspector should have gone to his property, determined after a site inspection that there would be no adverse impact, and granted a minor shoreline structure permit, he said.

Art Challacombe, DPP deputy director, said the bill would reverse a shoreline review process that has existed since 1970.

The department does issue minor shoreline structure permits, but only for structures that are "small, inexpensive and easy to remove." Two rock walls, such as the ones built without any permits by Green, are designed to be permanent and would not be allowed by permit.

Only an environmental assessment can determine the long-term impact a structure might have on a shoreline, Challacombe said. No one imagined two decades ago that beachfront homes along the North Shore’s Rocky Point could be threatened by high waves as they were in January, he said.

An environmental assessment also allows for public review and a variance application calls for a public hearing, he said.

"Is the city’s policy to protect homes and sacrifice sandy beaches, or is the city’s policy to retreat from the eroding shoreline? I don’t have an answer to that," Challacombe said. "That’s a policy question the Council will have to tackle."

The state Department of Land and Natural Resources issued a statement voicing reservations about the bill.

"Given what we know about sea level rise predictions, seawalls and other shoreline hardening structures will negatively impact Hawaii’s sandy beaches," DLNR spokeswoman Deborah Ward said in an email.