Huge pipes being tunneled underground near the intersection of Powers Boulevard and Constitution Avenue is the first big sign after almost two decades of work to increase the water available to the Colorado Springs area by a third.

The pipeline is part of the Southern Delivery System (SDS), a Colorado Springs Utilities (CSU) project that will pump water through more than 50 miles of pipes from the Pueblo Reservoir to Colorado Springs, Fountain, Security and Pueblo West. It will also filter clean water and store leftover water.

SDS, one of the largest water projects in the West, is the most expensive project CSU has ever undertaken. It has seen a grueling planning process of environmental reviews and permitting since the need for more water was recognized in 1996.

Pipeline construction at the busy intersection is ahead of schedule, expected to be complete in September rather than November, said SDS spokesperson Janet Rummel.

Construction started in January to minimize impacts on local businesses' peak shopping season during the holidays. CSU has kept at least one lane open in both directions during construction and had signs put up to direct traffic to other shopping center entrances when necessary.

The pipeline will take water from the new SDS treatment plant into the city's existing water system.

A $125 million facility that will be able to process 50 million gallons of water a day, the treatment plant on the east side of Colorado Springs is halfway constructed, also ahead of schedule. Construction began in March 2013 and will be finished in fall of 2015. The plant is expected to put out drinking water in April 2016.

SDS is jointly owned with Pueblo West Metropolitan District, Security Water District and the City of Fountain, but CSU will use 89.6 percent of SDS's water.

The whole project is cheaper than expected.

SDS construction is estimated to cost $847 million - $147 million less than the original estimation in 2009.

Rummel said money was saved by asking engineers to make designs that would be cost-effective without damaging drinking water quality, like keeping every part of the water treatment plant under the same roof instead of separate buildings.

This means SDS will cause less of a utilities rate increase for CSU customers than originally expected in 2009.

Colorado Springs is the second-most populated city in Colorado, and SDS will help it continue to grow.

Last year, CSU brought water to 458,716 people in Colorado Springs, suburban areas outside city limits, Ute Pass communities and military bases. The additional water that SDS will provide would allow CSU to serve about 608,552 people, the size Colorado Springs is expected to grow to in 2040.

"This is the future of Colorado Springs," said Jay Hardison, CSU water treatment plant project manager.