Almost one third of the planet’s largest groundwater basins are being rapidly depleted, according to a report from NASA this week.
The studies cited in the report show that 21 of the 37 largest aquifers in the world have passed the point of sustainability, while 13 of those are seeing almost no water return back to the water table. The studies concluded humans are using large amounts of groundwater reserves without knowing when they will run out.
The water table is replenished by rain and other precipitation, but because increased agriculture and industries like mining use more water, it's leaving the ground faster than it is being put back in.
NASA said climate change and increases populations would only intensify the problem.
"Available physical and chemical measurements are simply insufficient," said UCI professor and principal investigator Jay Famiglietti, who is also the senior water scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.
"Given how quickly we are consuming the world’s groundwater reserves, we need a coordinated global effort to determine how much is left.”
The places with the driest climates are contributing to the most unsustainable water use, including the drought-stricken state of California, which currently relies on groundwater to provide for 60 per cent of the population's cities and farms.
As a result, the state has had to drill deeper into the ground to find water, pushing past ground that has collected water for decades and even centuries.
"What happens when a highly stressed aquifer is located in a region with socioeconomic or political tensions that can’t supplement declining water supplies fast enough?" asked Alexandra Richey, the lead author on both studies, who conducted the research as a UCI doctoral student.
"We’re trying to raise red flags now to pinpoint where active management today could protect future lives and livelihoods."
ALSO ON HUFFPOST
What A Drought Looks Like
Lake Mead At Historic Low Levels Amid Drought In West(01 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: A buoy sits next to a puddle at the now closed Echo Bay Marina on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
California Firefighters Undergo Training For Controlled Burns During Wildfires(02 of43)
MT. HAMILTON, CA - JUNE 03: 3: Cal Fire firefighters walk through smoke during a live fire training on June 3, 2015 in Mt. Hamilton, California. Cal Fire firefighters are training ahead of what is expected to be an explosive wildfire season as California pushes through its fourth year of severe drought. The state has had over 1,000 wildfires since the beginning of the year. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(03 of43)
A cow feeds her calf near the banks of the Guacerique river - now a trickle - which flows into the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
ENVIRONMENT-US-TOURISM-DROUGHT-YOSEMITE(04 of43)
Burnt trees after a recent wildfire at the Yosemite National Park in California on June 3, 2015. It is one of America's most popular natural wonders. But even Yosemite National Park cannot escape the drought ravaging California, now in its fourth year and fueling growing concern. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year. But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
California Firefighters Undergo Training For Controlled Burns During Wildfires(05 of43)
MT. HAMILTON, CA - JUNE 03: A Cal Fire firefighter practices extinguishing a grass fire during a live fire training on June 3, 2015 in Mt. Hamilton, California. Cal Fire firefighters are training ahead of what is expected to be an explosive wildfire season as California pushes through its fourth year of severe drought. The state has had over 1,000 wildfires since the beginning of the year. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Drought-Plagued California Gives Salmon A Boost Downstream(06 of43)
RODEO, CA - JUNE 02: Thousands of young fingerling Chinook salmon are released into a holding pen in the San Pablo Bay on June 2, 2015 in Rodeo, California. As California continues to suffer through severe drought, low water levels on the state's rivers have forced wildlife officials to truck millions of young Chinook salmon hundreds of miles toward the Pacific Ocean in tanker trucks to assist the fish with migration. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(07 of43)
A man feeds his cattle near the banks of the Guacerique river - now a trickle - which flows into the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
ENVIRONMENT-US-TOURISM-DROUGHT-YOSEMITE(08 of43)
Children play on the exposed sandy bottom of Mirror Lake that is normally underwater and used by visitors to photograph reflections of the Half Dome rock monolith at Yosemite National Park in California on June 4, 2015. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year.But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(09 of43)
The head of a doll lies on the dried bottom of the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
ENVIRONMENT-US-TOURISM-DROUGHT-YOSEMITE(10 of43)
Vew of the Half Dome monolith from Glacier Point at the Yosemite National Park in California on June 4, 2015. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year. But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(11 of43)
A man takes a bath at the Guacerique river - now a trickle - which flows into the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(12 of43)
A cow drinks water from the Guacerique river - now a trickle - which flows into the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(13 of43)
The head of a doll lies on the dried bottom of the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
HONDURAS-WEATHER-DROUGHT-EL NIÃO(14 of43)
Picture of the dried bottom of the Los Laureles dam reservoir that supplies water for Tegucigalpa, on the outskirts of the capital, on June 2, 2015. Honduras has been hit by a major drought caused by 'El Nino' climate phenomenon, a band of unusually warm Pacific ocean temperatures, which in the past has been linked to numerous floods, droughts and bush fires from South America to Australia. The drought has killed thousands of cattle and dried up crops. AFP PHOTO / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images) (credit:ORLANDO SIERRA via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(15 of43)
Farm workers graft grape vines near Ione as a severe drought continues to affect California on May 27, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(16 of43)
Dried mud and the remnants of a marina is seen at the New Melones Lake reservoir which is now at less than 20 percent capacity as a severe drought continues to affect California on May 24, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(17 of43)
Dried mud and the remnants of a marina are seen at the New Melones Lake reservoir which is now at less than 20 percent capacity as a severe drought continues to affect California on May 24, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(18 of43)
A dried up section of the New Melones Lake reservoir is seen which is now at less than 20 percent capacity as a severe drought continues to affect California on May 26, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
ENVIRONMENT-US-TOURISM-DROUGHT-YOSEMITE(19 of43)
People picnic on the exposed sandy bottom of Mirror Lake that is normally underwater and used by visitors to photograph reflections of the Half Dome rock monolith at Yosemite National Park in California on June 4, 2015. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year.But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(20 of43)
The American flag flies beside an almost dry section of the New Melones Lake reservoir which is now at less than 20 percent capacity as a severe drought continues to affect California on May 26, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(21 of43)
A dead tree is seen on a dried section of the New Melones Lake reservoir which is now at less than 20 percent capacity as a severe drought continues to affect California on May 24, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(22 of43)
A farmer ploughs his dusty field in Sheldon as a severe drought continues to affect California on May 25, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(23 of43)
A farmer ploughs his dusty field in Sheldon as a severe drought continues to affect California on May 25, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-CALIFORNIA-DROUGHT(24 of43)
A pontoon bridge sits on a dried up section of the the Oroville Lake reservoir which is now at less than 25 percent capacity as a severe drought continues to affect California on May 24, 2015. California has recently announced sweeping statewide water restrictions for the first time in history in order to combat the region's devastating drought, the worst since records began. AFP PHOTO/ MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
ENVIRONMENT-US-TOURISM-DROUGHT-YOSEMITE(25 of43)
Dead trees in front of the Half Dome monolith at the Yosemite National Park in California on June 3, 2015. It is one of America's most popular natural wonders. But even Yosemite National Park cannot escape the drought ravaging California, now in its fourth year and fueling growing concern. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year. But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images) (credit:MARK RALSTON via Getty Images)
US-ENVIRONMENT-WATER-PROTEST-NESTLE(26 of43)
Activists protest outside a Nestle water-bottling plant where they demanded that the company halt its water-bottling operations in response to the state's drought in Los Angeles, California on May 20, 2015. A simultaneous rally was held at a plant in Sacramento amid California's fourth year of drought. AFP PHOTO / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images) (credit:FREDERIC J. BROWN via Getty Images)
US-ENVIRONMENT-WATER-PROTEST-NESTLE(27 of43)
Activists protest outside a Nestle water-bottling plant where they demanded that the company halt its water-bottling operations in response to the state's drought in Los Angeles, California on May 20, 2015. A simultaneous rally was held at a plant in Sacramento amid California's fourth year of drought. AFP PHOTO / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images) (credit:FREDERIC J. BROWN via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(28 of43)
LAKE MEAD NRA, NV - MAY 13: Pipes for a water intake pump sit on an area of Pyramid Island that used to be under the waters of Lake Mead near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(29 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 13: Tire tracks are visible in dry cracked earth that used to be the bottom of Lake Mead near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(30 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 13: A pool stands empty at an abandoned hotel at Lake Mead near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(31 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 13: Dead brush stands on what used to be the bottom of Lake Mead near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(32 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 13: Pipes for a water intake pump sit on dry land in front of Pyramid Island near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(33 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 13: Dry cracked earth that used to be the bottom of Lake Mead is seen near Boulder Beach on May 13, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(34 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: Water leaks from a pipe onto the banks of Lake Mead near Upper Government Wash Cove on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(35 of43)
OVERTON, NV - MAY 12: Dry cracked earth is seen at the Overton Wildlife Management Area on May 12, 2015 in Overton, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(36 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: An old Hamms beer can sits on what used to be the bottom of Lake Mead at the abandoned Echo Bay Marina on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(37 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: A sign warning boaters of low water levels is posted near the Echo Bay boat launch on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(38 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: Wind kicks up dust along Boulder Beach at Lake Mead on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(39 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: Tires once used as a breakwater sit on dry land at abandoned Echo Bay Marina on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(40 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: Wild horses walk through dry brush on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
Lake Mead At Historic Low Levels Amid Drought In West(41 of43)
LAKE MEAD NATIONAL RECREATION AREA, NV - MAY 12: The Desert Princess paddle wheeler passes by a tall bleached 'bathtub ring' on the rocky banks of Lake Mead near the Lake Mead Marina on May 12, 2015 in Lake Mead National Recreation Area, Nevada. As severe drought grips parts of the Western United States, Lake Mead, which was once the largest reservoir in the nation, has seen its surface elevation drop below 1,080 feet above sea level, its lowest level since the construction of the Hoover Dam in the 1930s. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)
DOMINICAN REP-DROUGHT(42 of43)
Santo Domingo residents get government-supplied potable water to mitigate one of worst droughts in the last 20 years affecting the country, on May 12, 2015. AFP PHOTO/ERIKA SANTELICES (Photo credit should read ERIKA SANTELICES/AFP/Getty Images) (credit:ERIKA SANTELICES via Getty Images)
California's 4-Year Drought Takes Toll On State's Sacramento Valley(43 of43)
YUBA CITY, CA - MAY 08: A water level marker stands in the middle of a dry reservoir on May 8, 2015 in Yuba City, California. As California enters its fourth year of severe drought, farmers are struggling to keep crops watered as wells run dry and government water allocations have been reduced or terminated. Many have opted to leave acres of their fields fallow. (Photo by Justin Sullivan/Getty Images) (credit:Justin Sullivan via Getty Images)