CLEVELAND, Fla. — Behind a large water storage tank draped with a huge American flag, several dozen local politicians, regional water agency staffers and engineers gathered Thursday to celebrate the completion of a $20 million pipeline across the Peace River.

The 12-mile transmission line will allow the Peace River Manasota Regional Water Supply Authority and Punta Gorda Utilities to ship up to six million gallons per day to each other, either to meet local or regional demands or provide water in case of emergency plant shutdowns.

Its completion represents a major milestone in a 25-year effort by the authority to interconnect water supplies within its four-county region.

“It’s difficult to get across to residents the value of water until you don’t have any,” said Pat Lehman, authority executive director, in remarks to the gathering.

He recalled that in 1998 the authority had only one pipeline to supply water from its plant on Kings Highway in DeSoto County, and it broke in a construction accident. That cut off Charlotte County and North Port from their chief source.

Since then, the authority has increased the number of interconnects tenfold in Charlotte, DeSoto, Sarasota and Manatee counties, Lehman said.

The pipeline will “benefit not only the rest of Charlotte County but the region as a whole,” said authority chairman Robert Skidmore, a Charlotte County commissioner.

Construction began some two years ago. Designed by the Venice firm DMK Engineering and built by the national firm Garney Construction, the 24-inch line runs south along the east side of I-75 from Kings Highway across the Peace River to Hollyman Drive. It ties into the city’s water system at the authority’s new water tank and pumping station on U.S. 17 at Disston Avenue.

The line also features connections to Charlotte County Utilities’ system in Deep Creek.

The pipeline could be used to allow Punta Gorda to stave off building a $28 million reverse-osmosis water plant, said Lehman. The City Council recently reconsidered that project as a way to reduce the hardness of its water during dry seasons.

However, the most important purpose of the pipeline is to provide supply alternatives in emergencies, several officials emphasized.

“This is a great day ­today,” said former authority chairman Dick Loftus, who supported the pipeline during his tenure in 2008-09. “It’s necessary to have interconnected water resources. You can have power failures or pipeline failures.”

The project took shape after a decade of wrangling between authority members, Charlotte County and the Southwest Florida Water Management District.

The authority first crossed the river with a pipeline to the east along U.S. 17 in DeSoto, but its planned extension southward to the Punta Gorda water plant on Shell Creek was abandoned after the authority’s partners refused to fund it.

Charlotte County Utilities then began drafting its own plan for a smaller Peace River pipeline. However, the water district then brokered a deal to co-fund the much bigger interconnect completed Thursday.

The district paid $7 million, the state $5 million and Charlotte County $8 million.

“There’s no limit to what we can accomplish if we use this model, of the partnership that was forged, throughout the state,” said Paul Senft, water district chairman.

Email: gmartin@sun-herald.com