CALGARY, Alberta, May 3 (Reuters) - Enbridge Inc said on Friday its 210,000 barrel per day North Dakota pipeline is shut down after a leak in the line was discovered during integrity tests. It estimates less than 10 gallons of oil leaked from the pipeline. The company said the line, which runs from Minot, North Dakota, to Clearbrook, Minnesota, and serves producers in the Bakken oil field, is expected to be closed for less than 24 hours while the cause of the leak is investigated. Enbridge said wildlife was not impacted by the leak and it is still assessing the environmental impact. The leak has been reported the regulators.