The Colorado River has finally washed over a sandbar, connecting with the Gulf of California for the first time in 16 years. This marked the culimation of a two-month effort to bring water to the parched delta region of the river.

This merger brought together fresh water from the highly-endangered Colorado with salt water in the Sea of Cortez. The waters merged as high tide rose over the sandbar on 15 May. Water from the river has been restricted due to human consumption and industrial uses. Connections between the two waterways have been rare over the last 50 years. 

The Colorado River stretches 1,450 miles, running through seven U.S. states and two in Mexico. The river starts in the La Poudre Pass Lake, located in Colorado's Rocky Mountains. Almost 18,000 cubic feet of water are discharged out of the river every second. 

The Sonoran Institute created a pilot channel, in order to increase the flow of water moving into the gulf from man-made freshwater sources. This included runoff from wastewater treatment plants, as well as agricultural sources. This water flooded into swampy mudflats called the Rio Hardy. This artificial flood helped encourage the river to join, once again, with the larger body of water which is its natural outlet. 

A five-year program called Minute 319 diverts one percent of the water in the river to create floods in the delta, similar to those that normally occur every spring. 

The program is aimed at bringing back plant and animals species that once thrived in the delta region. The delta is currently choked with large numbers of invasive tamarisks, an invasive variety of salt cedar that thrives in the highly-saline environment. 

"The river once delivered its entire annual discharge of approximately 14 million acre-feet of fresh water to the upper Gulf of California, creating one of the largest and most diverse estuaries in the world," the Sonoran Institute wrote on a Facebook page supporting environmental efforts in the delta. 

Conservationists are hoping to restore a more-natural region of water/land interface, called a riparian habitat. This could include species such as willows and cottonwoods. 

A pulse flow of water was also released from the Morales Dam on 23 March, in a further effort to water down the region. It took almost six weeks for the water to reach its final destination, reconnecting the water sources. 

Deltas and estuaries, the places where rivers and seas connect, are among some of the most biologically diverse areas on the planet.