US farmers look to water reuse, as reservoir level drops

Water reuse in agriculture is gaining ground in the USA as farmers and water technologists seek to overcome the domestic water supply shortages caused by drought. The latest figures from the US Bureau of Reclamation show that water levels at Lake Mead, Nevada, the largest reservoir by capacity in the USA, hit a record low of 1,074 feet in March.

Two water reuse in agriculture projects — an indoor urban farm in St Paul, Minnesota, and a salad farm in the Salinas Valley, California — are highlighted in a new videofrom the WateReuse Association, Water Environment & Reuse Foundation, and global water solutions provider Pentair, released this week to coincide with the WateReuse Research Conference in Denver, Colorado.

In the video, Dave Haider, president of Urban Organics, a company using aquaponics to grow fish and plants indoors in Minnesota, said that a “symbiotic cycle” of water reuse between fish farming and plant cultivation was reducing water and energy use. Urban Organics uses 98 per cent less water than traditional farming, and grows seven times more per acre, Haider said.

In the Salinas Valley, sea water intrusion has gradually affected the aquifers that growers draw water from. However, before going ahead with water reuse, technologists first had to win approval from Monterey Council’s environmental health officer, who was sceptical. “We spent 11 years studying everything he thought might be a problem with the safety of the water, looking at viruses, bacteria, heavy metals, workers’ safety and consumer safety,” said Bob Holden, principal engineer of the Monterey Regional Water Pollution Control Agency (MRWPCA).

The official was eventually persuaded, and the project went ahead. “The benefits are that groundwater levels have recovered, and are rising, and that sea water intrusion is slowing,” said Brent Buche, deputy general manager, MRWPCA. Organic nitrogen levels in the water are also high.

Dr Phillip Rolchigo, vice president, technology, Pentair, added: “The statistics point to 70 per cent of the world’s water is used for agriculture. If we can’t feed the world, we’re going to have some really major challenges. Water reuse technologies, taking municipal water, treating and reusing that water and supplying our farms, can change that. Water reuse in agriculture is important, and it’s going to continue to grow.”