[A] report...by the development charity Progressio, has found that industrial production of asparagus in Peru's Ica valley is depleting the area's water resources so fast that smaller farmers and local families are finding wells running dry...It warns that the export of the luxury vegetable, much of it to British supermarkets, is unsustainable in its current form...We asked the leading UK retailers to comment but only two were able to do so...M&S said: "We have a range of responsible water use projects under way and have strengthened our farming standards to include greater focus on water efficiency." Tesco said: "...We have a strong record in this area and our Nurture standard is regularly reviewed and improved. We acknowledge there is more to do and so we are continually working with our suppliers to help them minimise their environmental impact, including water use."