The united states largest producer of potassium chloride operates these striking evaporation ponds in utah the ponds are filled with a mixture of water with potassium and salts which have been brought up from 1200m below the earths surface a dye is added to aid the evaporation of the water to leave behind around 700 1000 tons of potash per day an aerial view shows the extreme contrast between their electric blue colouring and the red brown of the desert dimensions 50 x 38cmnumber of piece