- This is a sustainable system as long as the groundwater is replenished as fast as it is pumped and used. It’s a steady source of water. To maintain the system, people’s use will need to be limited to what’s available to avoid over-pumping, or other water sources need to be found.
- Wells and water sources can dry up with overuse. If they just dig deeper to find the water, they will just drain that as well, compounding the problem. As the water table lowered, the stream water entered into the ground water. If that had been ocean water, the salinity of the water would have killed plants, been unsuitable for drinking, irrigation, or industry.
- When water leaves the ground, it leaves a hole, allowing the land above it to cave in, crush down. If the ground sinks, it can damage buildings and roads as well as create a flooding risk.
In this photograph of California’s San Joaquin Valley, the dates on the pole mark the former heights of the ground. In the span of 50 years, water pumping for irrigation led to nearly 30 feet of subsidence.