Manitoba Hydro and SaskPower have inked a 20-year hydroelectricity deal.

The agreement will see a minimum of 100 megawatts of electricity — enough to power 40,000 homes — flow from Manitoba to Saskatchewan annually, beginning in 2020.

Manitoba Premier Greg Selinger said the deal will help the province's economy while, at the same time, providing enough revenue to keep Manitoba's hydro rates down.

The deal will require 18 per cent of the energy generated from the still-under-construction Keeyask station on the Nelson River in northern Manitoba. Approximately 750 people are at work on Keeyask with peak employment expected to reach approximately 1,400 workers in the summers of 2016 and 2017, the province said.

"The energy we will supply to SaskPower is clean, renewable hydroelectricity that is surplus to the needs of Manitobans. The revenues from the sale will assist in offsetting the costs of Keeyask and keep rates low for our customers in Manitoba," said Manitoba Hydro interim president and CEO Darren Rainkie.

As part of the SaskPower agreement, a new 80-kilometre-long, 230,000-volt transmission line will be built between Birtle, Man., and Tantallon, Sask.