How Not To: Build an Inland Sea

When Life Gives You Massive River Flooding, Make Lemonade
In a fit of early 1900s nature-subduing enthusiasm, the good people of California decided to turn Imperial Valley (a desert) into a vast agricultural paradise (not a desert). To do so, they started cutting irrigation channels from the Colorado River. When those filled up with silt, they cut a little deeper, digging out a large gap in the River's bank to increase flow. Then, in 1905, the floods came, washing out the engineered canal and pouring thousands of gallons of water directly from the River into a previously dry below-sea-level basin. It took two years to get the flooding under control, by which point the basin had become a lake—the Salton Sea. In 1907 the first sport fish were imported and a tourist attraction was born.

Put Your Trust in Runoff
With the broken canals now repaired, the Salton Sea had no inlet or outlet. Instead, all it's water came from farm irrigation runoff. At first, nobody saw this as a problem. Then the Sea's salinity (and pollution levels) started to increase. Turns out, farmers were pulling water from the Sea, putting it on their crops, and letting it flow back in. Each time, the water picked up a little more salt and a few more pesticide chemicals. Eventually, this led to outbreaks of algae, massive fish die-offs, and a salinity level greater than the Pacific Ocean.

Assume You Won't Have To Deal With More Flooding In the Future
By the 1960s, regardless of its increasingly salty nature, the Salton Sea had become one of California's busiest tourist attractions and it's most popular state park. Investors built swanky resorts, but, unfortunately, nobody thought to build flood control systems. Then came 1976, when a tropical storm hit the area, marking the beginning of seven years of extra-heavy rains. Most of the new developments ended up underwater or bankrupt as investors bailed. Worse, increased runoff meant that even more chemicals and salt poured into the Sea. By the 1980s, there was little left of the once-thriving fishing and boating industries. Today, the Sea is home to several half-flooded trailer-park communities and one thriving bird sanctuary. Still ever saltier, it's expected to lose most of its fish population in the next few years.