Hercules had to change the courses of the Alpheus and Peneus rivers to clean the Augean stables.

The BJP will have to go one up on the mighty mythological hero and translocate three rivers from south Bengal to north Bengal if the party wins the Assembly elections and wants to implement a promise made in its manifesto.

“We will introduce the Utoject for the Bhairab-Sialmari-Jalanga basin with a 2,000 crores rupees fund for upgradation of existing irrigation network and construction of new canals,” reads the BJP manifesto, which was released on Sunday in the presence of Union home minister Amit Shah.

The promise has left riparian experts racking their brains on how rivers flowing southwards through Murshidabad, which is part of south Bengal, can help develop a command area in the northern districts of the state.

A river expert said that using south Bengal rivers for irrigation in north Bengal was an impossibility.

If the BJP has a plan that actually gets around such geographical obstacles, the party so far does not appear to have shared the specifics with some of those associated with drawing up the manifesto.

Subhash Sarkar, the BJP’s Bankura MP who was in charge of the manifesto committee, was measured in his response. “When we have put it in the manifesto, there must be some plans to channel the water from these rivers towards the northern districts,” Sarkar said.

If the BJP is unable to clear the air soon, its opponents are certain to cite the promise as another example of the party’s unfamiliarity and disconnect with Bengal. A perceived cultural schism with Bengal has already given the Trinamul Congress a stick to beat the BJP with.

The three rivers mentioned in the 13th page of the manifesto are on the right bank of the Ganga, the mighty river that divides north and south Bengal, and flow through Murshidabad district.

The Bhairab and the Sialmari merge with the Jalangi (referred to as “Jalanga” in the manifesto) at different locations in Murshidabad district and the Jalangi eventually joins the Hooghly near Mayapur in Nadia district.

“All these three rivers are distributaries of the Ganga and flow southwards…. How can they help develop a command area in the northern districts, which are on the left bank of the Ganga and beyond?” asked renowned river expert Kalyan Rudra.

A retired officer of the state irrigation department could not hide his astonishment when told about the promise involving the three rivers.

He said that if any command area had to be developed in the northern districts of the state, water from the Ganga itself could be channelled for the purpose.

“Also, several other rivers flow through north Bengal and their water can be used to irrigate the northern districts. There appears to be a lack of understanding among those who drew up the manifesto,” he said.

Tuhin Subhra Mondal, a Balurghat-based researcher who has worked on river conservation for years, said the promise involving the rivers meant very little.

He said the manifesto’s silence on the conservation or use of rivers that flow through north Bengal made it clear there was no plan on river or basin management.

“It seems that those who have penned the point lack basic geographical knowledge. There is not a word about the rivers of north Bengal, particularly the Teesta, which has been emerging as an issue for the various political parties because the water-sharing treaty is still pending with Bangladesh,” said Mondal.

Sarkar, the BJP MP, said: “We also have plans for the Teesta.”

Additional reporting by Snehamoy Chakraborty in Bolpur and Alamgir Hossain in Murshidabad