A young leopard frog confronts a drying stream bed during a drought in the lower central plains of Missouri. One-third of all river and lake basins in the world are facing water scarcity. Freshwater species quickly decline as water is diverted for agriculture and other uses.

After 2011 record temperature, Medina Lake is filled to just 25% of its capacity. Located northwest of San Antonia, the reservoir sits along the recharge zone and helps filter water underground to the Edwards Aquifer.

Water flows into the Mexican portion of the Colorado River in San Luis as a result of the opening up of the Morelos dam and a landmark agreement between the US and Mexican governments. Like many major rivers, the Colorado is being completely depleted by human use at times, with all water being diverted before the river reaches the ocean.

Juan Butron looks at the remnants of the mighty Colorado river near the Morelos dam behind him, which marks the border between the US and Mexico, and diverts 1.55m acre feet of the river into Mexican irrigation canals that supply farmers in the Mexicali Valley with water and Tijuana, Tecate and Mexicali municipalities with water.

Colorado River near Mexicali in Baja California, Mexico. In the water-scarce regions of the world, more than 90% of all water consumed goes to farms. In most parts of the world alleviating water shortages will require finding ways to use less water on farms.

An aerial view of the mouth of the Colorado River in Mexico.

Irrigated fields at Ute Mountain Farm and Ranch bring some green to the otherwise arid plains of southwestern Colorado. Half of all cities and three-quarters of irrigated farming areas in the world have experienced water scarcity.

An irrigation channel stretches across the San Luis Valley with the the Sangre de Cristo Mountains in the background near Monte Vista, Colorado. In some places in the US, cities, industries and farmers can use water markets to buy and sell water; shifting usage when supplies are limited. But nature’s needs are often left unmet.

Green US farmland separated from the dry desert by the USA/Mexican border and an irrigation canal.

Red gum trees hanging over the banks of the Murray River in Australia A recent report from WWF International estimates that global freshwater species populations declined by 76% between 1970 and 2010. The Murray-Darling Basin offers a dramatic example of these consequences. Low water flows in some rivers have led to periodic blooms of toxic blue-green algae, which not only choke out fish and other aquatic life but also render the river unusable for human consumption or even irrigation in some cases.

Conservation interests and agencies gathered along the Murray River in Australia to witness the return of water to a wetland system that now rarely receives floodwater from the river, due to construction of large water-storage reservoirs built upstream that capture the river’s flow and send it to irrigated farms.