More than 150 million people have directly benefited from a massive water-diversion project that has been pumping water from major rivers in the south to the drought-prone north over the past eight years, authorities said Monday.

The South-to-North Water Diversion Project has diverted 58.6 billion cubic meters of water to arid regions in the north through its middle and eastern routes, according to the Ministry of Water Resources.

Annual water transfers have risen from more than two billion cubic meters to nearly 10 billion cubic meters. The project has helped 42 middle and large-sized cities to bolster the local economy.

In terms of the ecological environment, the middle route of the project supplied over nine billion cubic meters of water for ecological water replenishment, effectively curbing the decline in groundwater level in the north.

The South-to-North Water Diversion Project has three routes. The middle route, the most prominent of the three due to its role in feeding water to the nation's capital, starts from the Danjiangkou Reservoir in central China's Hubei Province and runs across Henan and Hebei before reaching Beijing and Tianjin. It began supplying water in December 2014.

The eastern route began operations in November 2013, transferring water from east China's Jiangsu Province to feed areas including Tianjin and Shandong.

The western route is in the planning stage and is yet to be built.