The reservoir would provide water for over 800,000 people in times of drought and salt water intrusion, said Nguyen Thien Phap, an official from the province’s Department of Agriculture and Rural Development.

It would cover the entire Nguyen Tat Thanh Canal, 19 kilometers long and 65 meters wide, passing through Chau Thanh and Tan Phuoc Districts. The canal links with the Tien River, a tributary of the Mekong River.

The province expects to spend two years constructing the reservoir, which will become one of the two largest manmade freshwater bodies in the delta once completed, besides Kenh Lap in Ben Tre Province.

"As salt intrusion kicks in this year, the province has interfered in time to prevent part of the salinity by building a temporary dam on the side that meets the Tien River. Accordingly, we have saved enough freshwater to support both daily and farming activities in the region," Phap said.

During the dry season this year, which normally lasts from late November to late April, Mekong Delta, home to 12 provinces and one city, was hit by the worst drought ever, alongside historic levels of salinity.

The rainy season arrived late last year and was shorter than usual, resulting in rainfall 8 percent lower than normal at 1,240 mm, according the Ministry of Agriculture and Rural Development.

A series of upstream dams in China have been blamed for holding back the natural flow of water supposed to run south, the sea level rise, and the gradual sinking of southern Vietnam.

Tien Giang and four other Mekong Delta peers, Ben Tre, Long An, Kien Giang and Ca Mau had to declare an emergency in early March, followed by Soc Trang last week.

By mid-March, saltwater had intruded 50-110 kilometers into major rivers, all branches of the Mekong, two to eight kilometers more than in 2016, when the region was hit by the worst drought in a century.

So far this year, drought and salt intrusion has damaged 43,000 hectares of rice fields and caused 80,000 families to lack water.