ADDIS ABABA, Ethiopia

Ethiopia on Wednesday warned of a “last chance” to reach an agreement on the filling and operation of the $5 billion dam being built by Addis Ababa on the Nile.

“This is the last chance,” Ethiopian Water Minister Sileshi Bekele said at the fourth and last round of talks between water ministers and technical experts from Ethiopia, Sudan and Egypt in the capital Addis Ababa.

The three countries have been in talks on the Grand Ethiopian Renaissance Dam (GERD) since March 2015, when they adopted a Declaration of Principles including the principle of “no significant harm” on downstream countries.

The talks have been expedited since last November after the U.S. and the World Bank joined in as observers on the call of Egypt.

“Ethiopia believes there are technical solutions to technical problems,” he said and added that the trilateral negotiations have never been about water sharing or water consumption.

For his part, Egypt’s Water Minister Mohamed Abdel-Aty said the three countries could bridge their differences as they have reached consensus on the “basic ingredients” of agreement including stage filling of the dam, drought mitigation and cooperation rule.

“We agreed on many basic ingredients but differences remained in the approach such as a definition of drought threshold,” Abdel-Aty said.

The ongoing construction of the dam on the Blue Nile, a Nile River tributary, has been a sticking point between the east African neighbors.

Ethiopia hails it as a critical step in its economic development, but Egypt fears the dam will reduce its traditional share of Nile waters as defined in the 1959 water-sharing treaty.

The Blue Nile is one of two main tributaries feeding the Nile River.

Sudan, a downstream country, has participated in several rounds of technical negotiations that failed to break the deadlock.