GRAND CANYON NATIONAL PARK, Arizona (AP) — Four major breaks in the water main that supplies the Grand Canyon mean visitors can’t stay overnight in hotels on the South Rim of Grand Canyon National Park during the Labor Day holidays.

Here are some things you should know about the Transcanyon Waterline.

When was the pipeline built

The Transcanyon Water Distribution Pipeline is a 12.5-mile (20-kilometer) pipeline built in the 1960s that carries water from Roaring Springs on the North Rim to the Havasupai Gardens pumping station and then to the park’s popular South Rim. It provides drinking water and fire protection for all South Rim facilities as well as some facilities in the inner canyon, including over 800 historic buildings.

Who does the pipeline serve?

The pipeline is the primary source of water for the approximately 2,000 residents of Grand Canyon Village, park staff, other employees and the millions of people who visit the national park each year.

Breaks in the pipeline

The aluminum pipeline to the South Rim winds around hiking trails and through rocky terrain. Sand in the water scratches the inside and creates weak spots that frequently break and leak. Each repair costs an average of $25,000.

The steel pipeline that leads to the North Rim dates back to the 1930s and is exposed to rockfall and freezing in winter because it runs above ground. A rockslide in 2017 damaged the pipeline to the North Rim, costing $1.5 million to repair in two weeks. The lodge there canceled reservations and water for drinking and firefighting had to be brought in.

Dealing with ageing infrastructure

The water main has exceeded its expected lifespan and failures continue to occur. Since 2010, there have been more than 85 major breaks that have interrupted the water supply.

The problem has been at the top of the park’s maintenance list for at least a decade, with engineering studies conducted and a portion of park entrance fees set aside to cover the costs.

The National Park Service recently began a $208 million renovation of the aqueduct and modernization of the associated water supply system, which is expected to be completed in 2027.