Highlighting the increasingly complex legal and environmental issue of whether beachfront homeowners should be allowed to armor their property against the eroding south shore, the West Tisbury conservation commission last week once again rejected plans for a large stone revetment on a private property on Tisbury Great Pond.

At issue is a proposed 135-foot stone revetment on the West Tisbury property of Wall Street financier Wesley Edens. Mr. Edens has been trying to armor his property for over a year. His house sits some 90 feet from the edge of the shoreline.

In March 2010 the conservation commission rejected Mr. Edens’ plans for a 170-foot stone revetment, scaled back from an original 255-foot plan. In October, after an appeal, the state Department of Environmental Protection approved a smaller plan for a 135-foot revetment under the state wetlands protection act. But last week, at a well-attended public hearing, the conservation commission, citing its stricter town wetlands bylaw and after consultation with third-party environmental engineers, unanimously rejected plans for the revetment. The commission recommended that the property owner explore “softer” solutions such as coir logs and sand envelopes to manage erosion. Mr. Edens needs both state and local permits to go ahead with his plans.

The commission has 21 days to issue a written decision; Mr. Edens is expected to appeal.

In its 2010 decision the conservation commission cited a provision of the West Tisbury wetlands protection bylaw concerning coastal banks and their environs. The bylaw allows only for projects “determined by the commission to have no adverse effect on bank height, bank stability, wildlife habitat, vegetation or the use of the bank as a sediment source.”

As that written decision records, “The applicant has not overcome the presumption of significance that the coastal bank is a sediment source to down drift or adjacent beaches.” In other words, the effect of the revetment on abutters was unknown. Revetments can interfere with the natural processes of shoreline erosion and can sometimes transfer the problem of erosion elsewhere. Mr. Edens has proposed shipping in 38 cubic yards of sand every year to counter those effects.

The Trustees of Reservations, whose Long Point Wildlife Reserve abuts the Edens property, objected to the plan.

“In general The Trustees of Reservations does not support shoreline armoring projects,” former Long Point superintendent Chris Egan wrote to the conservation commission in 2010. “The sand spit to the south of the project area is suitable habitat for and has had nesting piping plovers and least terns. The shoreline adjacent to the project area was used as feeding area for piping plover chicks.”

In its decision last Tuesday the conservation commission relied on the expertise of two third-party environmental engineers as well as the Martha’s Vineyard Commission.

One report, from Stanley Humphries of the environmental firm LEC, ordered by the commission and paid for by the applicant, found that the construction of the revetment would adversely impact storm damage prevention and wildlife habitat.

The other report, from consultant Greg Berman of the Woods Hole Sea Grant Program, highlighted the differences between state and local wetlands protection regulations. Mr. Berman said state law provides for the construction of revetments to “prevent storm damage to buildings” where the town bylaw more specifically pertains only to those structures in “imminent danger.”

“Looking at this site through the lens of the West Tisbury wetlands protection bylaw regulations is quite different than solely looking at the State Wetlands Protection Act,” Mr. Berman said in the report. “While a coastal engineering structure at this site may prevent storm damage at some point in the future, a possible 40-plus year timeframe before the top of the bank reaches the deck of the house is not ‘imminent.’”

In a letter, Martha’s Vineyard Commission coastal planner Jo-Ann Taylor said the Island Plan specifically calls for minimizing shoreline armoring.

“As erosion rates increase with sea level rise, pressure will increase to armor shorelines to protect houses,” the plan says. “However this just directs the erosive forces to the next unprotected shoreline down-drift and prevents beaches from rebuilding such natural storm defenses as dune systems.”

The conservation commission meets again on Sept. 8 to discuss the written decision.