A controversial bill that environmental groups said would weaken protection for Pennsylvania’s cleanest streams won final approval by the state’s General Assembly on Wednesday.

The final bill was little changed from one passed a week earlier by the House that was backed by builders but strongly opposed by environmental groups.

The bill would change a regulation adopted by the Department of Environmental Protection in 2010 that requires projects disturbing more than an acre of land in state-designated high quality and exceptional value watersheds to provide a 150-foot forest buffer along streams.

Instead, the bill says a 100-foot buffer “may be used as a preferred choice” along streams but allows developers to substitute other stormwater control practices.

The Senate slightly changed the House language to say that the substituted pollution control practices had to be “substantially equivalent” to a stream buffer.

Environmental groups had contended in their comments that no other practices provide both the pollution control and in-stream habitat benefits as forest buffers.

The Senate version also included language saying that removed buffers had to be replaced “as close as feasible” to the area where they are removed. The earlier version had only required that replacements be planted in the same watershed.

After the Senate passed the amended version on a 27-22 vote Tuesday, the House adopted the revised bill Wednesday, sending it to Gov. Tom Corbett.

In a last-minute letter to lawmakers, the Chesapeake Bay Foundation called the Senate tweaks to the bill “ambiguous,” adding “the science is clear — there is simply no scientifically equivalent practice equal to forested riparian buffers.”

The state is already falling short of its Bay cleanup plan goal of planting 109,735 acres of forest buffer by 2017, and the legislation would make that job even more difficult as the state would likely to begin losing already established buffers, CBF said.

Besides CBF, the legislation was opposed by numerous other organizations such as the Pennsylvania Chapter of The Nature Conservancy, the Pennsylvania Council of Trout Unlimited  and Citizens for Pennsylvania’s Future, among others.

The state Fish and Boat Commission also opposed the bill, as did former Department of Environmental Protection Secretary David Hess.

Hess, who served in the administrations of Republican Governors Tom Ridge and Mark Schweiker, said in a letter to lawmakers that forested buffers were “the most effective and least costly” way to reduce stream pollution and protect habitat. He noted that only 4 percent of watersheds in the state are designated as high quality or exceptional value, and that the rule requiring the buffers contained nine different exemptions and six different waivers from the requirement, including single family homes not part of a development; pipeline maintenance; and oil, gas timber and mining operations.

“Pennsylvania is facing significant mandates to meet water quality standards under the federal Clean Water Act in every watershed in the Commonwealth as well as in special areas like the Chesapeake Bay, Lake Erie and Ohio River watersheds,” Hess wrote. “To deny us the use of tools like stream buffers in our best watersheds will impose additional costs on taxpayers they can ill afford in today’s economy.”

In testimony to a House Committee earlier this year, a DEP representative indicated she did not know of any requests for a waiver from the regulation that had been denied.

Nonetheless, passage of the bill had been a priority for builders and developers who argued that it imposed extra burdens on landowners.

State Sen. Lisa Baker, a Republican who represents several counties in Northeastern Pennsylvania which has many high quality and exceptional streams, characterized the bill as a “landowner/property rights bill” that seeks to “develop a balance between responsible development and environmental protection.”

“I’m not interested in paving the way for huge developments nor trying to punch holes in clean water,” she said. “My interest is in giving relief to landowners who find they can not do improvements to their property costing jobs and opportunities that rural areas can ill afford to lose.”