The Colorado River Delta once provided nearly 2 million acres of wetlands and freshwater supporting thousands of fish and wildlife species. The vibrant ecosystem sustained indigenous populations for thousands of years.

But a population boom, coupled with an economy built on agriculture in the western United States and northern Mexico, put such an enormous strain on the water supply that it could no longer sustain the delta’s ecosystem. Exacerbating the problem was the construction of major dams, including the Hoover Dam, along with dozens of irrigation canals in the 1930s—nearly all on the U.S. side of the border. This left the river’s last drops to evaporate in the Sonoran Desert before reaching the Sea of Cortez, devastating the delta’s ecosystem. The once extensive wetlands now only cover 5 percent of their historic high.

This past spring, however, the Colorado River flowed its natural course all the way to the sea for the first time in 16 years and will continue to do so every spring for the next five years, thanks in part to Squire Patton Boggs and Arizona-based partner Peter Culp, who worked pro bono to help hammer out a landmark binational agreement between the United States and Mexico on the management of the Colorado River and its tributaries.

Although the water that now pulses through the ground as a result of the agreement is nothing compared with the mighty currents that once were, it is a victory nonetheless, and one that was many years in the making. On November 20, 2012, the commissioners of the U.S. and Mexican sections of the International Boundary and Water Commission signed Minute No. 319, which provided that both countries would share both the benefits and the burdens of reservoir storage along with the allocation of water flow through the delta to bring its ecosystem closer to its previous natural state.

The agreement allocates about 1 percent of the river’s flow toward recreating the former naturally occurring spring floods in the Colorado River Delta. The goal is to bring back the abundance of wildlife that used to inhabit the delta.

Minute 319 is a follow-up to three previous agreements, all of which embrace a series of operational measures and cooperative projects that will be undertaken by the U.S. and Mexico during a five-year “pilot period” that will last through Dec. 31, 2017. Minute 319 also creates a framework by which Mexico can conserve and store water in the U.S. reservoir system.

For Culp, who devoted countless pro bono hours toward the project while a partner at Squire Sanders before it merged with Patton Boggs in May, the Colorado River has long fascinated him, but his interest was heightened after reading a book in college about the history of U.S. land development and water policy called “Cadillac Desert” by Marc Reiner.

Prior to his legal career, Culp managed a nonprofit public health technology enterprise for C. Everett Koop, the former U.S. surgeon general. He also managed forest fires in the Northern Rockies and drove long-haul refrigerated freight in the U.S. and Canada.

“It was the surgeon general who noticed my intrigue in environmental law and suggested I go to law school,” Culp told The Am Law Daily in an interview.

After graduating from law school magna cum laude in 2001, Culp started with the then Squire, Sanders & Dempsey, prior to its 2010 merger with Hammonds. “At one point I left Squire for about a year and a half to work in-house at the Sonoran Institute, and I continued working on the Delta and other Colorado River matters during that period from my in-house position, then took up the work again pro bono after returning to Squire sometime around late 2005.”

Over the past decade, Culp has also served on a variety of boards and commissions related to water and natural resources issues. Arizona governors Janet Napolitano and Jan Brewer have consistently appointed him to the Colorado River Advisory Commission, where he has served since 2004.

Culp attributes much of his Minute 319 achievements to the tightly knit cooperative effort among a number of nongovernmental organizations—such as the Environmental Defense Fund, Pronatura, Sonoran Institute and the Colorado River Delta Water Trust—as well as his firm, where he works as a partner specializing in water and natural resources law and environmental law.

“It has been a 14-year labor of love, but thanks to the NGOs’ efforts to find us some funding and the generosity of a couple of key donors, I’ve been able to dedicate more time to it in recent years than might have otherwise been possible,” Culp says.

Prior to its merger with Patton Boggs, Squire Sanders had made a name for itself in environmental law. In January, U.S. Secretary of the Interior Sally Jewell gave the firm the “Partners in Conservation Award” for its work on Minute 319.

Mary Kelly, former vice president of Texas-based Rivers and Deltas for the Environmental Defense Fund, has spent nearly 30 years as an environmental lawyer, much of it working on Colorado River issues. She notes the critical role Culp played in the landmark agreement.

“He’s going to be an important person as the levels of water are sinking,” Kelly says.