LIMA, Peru —- The police and demonstrators opposed to an irrigation project in the south of the country clashed Thursday, killing one man and injuring 18, as President Alan Garcia faced a new conflict over natural resources in Peru’s surging economy.

The skirmish occurred before dawn in the town of Espinar, 400 miles south of Lima, officials in Peru’s human rights office said. Police officers fought with protesters who contended that the Majes-Siguas II irrigation project would leave Espinar without water, said Silvio Campana of the human rights office, which tries to mediate conflicts. The man who died was a bystander, officials said.

The irrigation project calls for a dam and water system capable of irrigating 95,000 acres of agricultural land in the region of Arequipa.

Peru’s government has encouraged the growth of the petroleum industry and of export-oriented agricultural farms to diversify the economy, which has traditionally depended on mining. The economy is forecast to grow by about 7 percent a year.

But conflicts over natural resources have weighed on Mr. Garcia, whose disapproval rating is nearly 60 percent. Last year, three dozen people died in a clash over land in the Amazon jungle where indigenous tribes oppose oil exploration.

Water is a sensitive issue in Peru, because desert covers its Pacific coast, where most of the population lives, and its Andean glaciers are melting because of climate change.

While the government has issued a decree guaranteeing the population’s water supply, residents of Espinar were upset that the state investment agency awarded a concession on Monday for the irrigation project to a private consortium called Angostura-Siguas without taking into account their concerns.

“The Province of Espinar has its own needs that have never been considered,” said Nestor Cuti, who leads the group of protesters and wants Mr. Garcia’s prime minister to open negotiations to end the standoff.

“With this concession we are condemned to have a lack of water for life,” Mr. Cuti said.

Prime Minister Jose Chang said the protests must stop for the government to agree to begin negotiating.

Mr. Chang said protesters had tried but failed to take over the nearby Tintaya copper mine, which is owned by the global metals firm Xstrata. Tintaya is an important mine in Peru, which is the world’s No. 2 copper-producing nation.

“We are sure we will be able to reach a solution that will be just for the town of Espinar,” Mr. Chang told reporters.

Finance Minister Ismael Benavides, who was sworn in Tuesday by Mr. Garcia, represented the government’s investment agency as the head of its water projects at a ceremony on Monday when the contract was awarded.

“I understand the worries about water among the people,” Mr. Benavides said Thursday on RPP radio. But he added, “This project is going to generate 150,000 or 200,000 jobs, and I’m sure much of them will go to Espinar.”