Restoration of the Colorado Delta and Estuary: The Great Experiment


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Colorado River and Delta Satellite View 2-1

Until the ‘pulse flow’ the Colorado River generally stopped before reaching the estuary. Image courtesy of Sonoran Institute. Modified by James Gibson

Stakeholders in the March 23, 2014 pilot ‘pulse flow’ from Mexico’s Morelos Dam into the Colorado Delta have high hopes.

They want their efforts to create an unprecedented adaptation model for water-sharing agreements elsewhere in the Colorado River Basin and beyond, even in the face of committed climate change.

The pilot ‘pulse flow’ arose from the November 2012 signing of Minute Order 319.

It was the first time in history that a bilateral agreement was signed by the US and Mexico that dedicates water to the river in Mexico and expands restoration efforts in the Delta.

What is the Pulse Flow?

The so called ‘pulse flow’ is a mimic of formerly naturally-occurring spring floods that trigger new growth of willows and cottonwoods which require flooding for seed germination, and then recede.

Periodic pulse flows are also essential to scour the channel and floodplain, thwarting the growth of salt cedar.

As part of the 5-year long Minute 319 interim agreement (it expires December 31, 2017), on March 23, 105,922 acre feet of water was released, augmented by a base flow of 52,696 delivered over a longer time period and at a lower rate.

The goal is to restore 950 hectares of habitat, allowing seeds of native trees to germinate and providing water for sustained growth.

Colorado River Laguna Grande Restoration Phases-1

Restoration Timeline at the Laguna Grande site on the Colorado River. Image courtesy of Sonoran Institute.

Nutrient-rich freshwater from the Colorado River touched the Upper Gulf’s salty tides March 27, 2014, the first time since 1998.

Historical Conditions in the Delta and Estuary

The triangular delta at the mouth of the Colorado River was once the place the conservationist Aldo Leopold (1887-1948), in 1922 called a “milk and honey wilderness.”

Before the dams the delta received all of the 15 million acre-feet of annual water flow from the United States. Now only ten percent of that flows across the border, all of which is legally consumed by municipal, industrial, or agricultural users in Mexico.

Likewise, at the gulf, so much fresh water flowed down the river that the tidal estuary originally extended approximately 25 miles (40 km) into the northern region of the Gulf of California. It was here that freshwater mixed with the seawater. This mixing created the perfect water chemistry and nursery grounds for a variety of wildlife – important to the region and its indigenous Cucapá.

Delta: Present Conditions

Today the delta is a desiccated land of salt flats and dry river channels and the estuary a fraction of its former self.

As a result, not only have plants, animals and marine life disappeared, but native people including the Cocopah and Cucapá- who have lived on the Delta for thousands of years- are now deprived of the landscape and river they used to hunt and fish.

But there is good news.

The present Colorado River riparian corridor in Mexico is a 70-mile long stretch of remnant habitat that still survives on groundwater and the drastically reduced flows of the Colorado River. In 2008, through a land concession agreement with the Mexican government, the Sonoran Institute and the conservation group Pronatura Noroeste secured a total of 1200 acres within the corridor to be dedicated to restoration.

Research on the hydrology, topography, soil, and existing vegetation types has since shown that the area has great potential for restoration.

Furthermore, the restoration pilot projects such as Laguna Grande have had very positive impacts on the habitat, wildlife, and the local communities in the region.

Colorado River and Laguna Grange restoration area map-1

Location of Laguna Grande Restoration Area within Colorado River Delta. Image courtesy of Sonoran Institute.

Prospects for Restoration of the Delta and Estuary

Both environments can be brought back to life, tree by tree, acre by acre. Not everywhere, of course, but certainly in key areas. All it takes is a little bit of fresh water. Then Mother Nature takes over; she has a way of making things work the best they can with very little. The challenge is getting the water.

As reported by Sandra Postel of the National Geographic’s Freshwater Initiative, research by Edward P. Glenn at the University of Arizona “suggests that allocating about one percent of the Colorado River’s historic flow to the river every year (rather than over five years, as Minute 319 does) – and delivering an annual base flow of 30,000-50,000 acre-feet and a periodic pulse flow of about 260,000 acre-feet – are needed to sustain the delta ecosystem over the long term.

Colorado River: Getting the Water

Historically, water-rights holders have had to adhere to policies that foster a “use it or lose it” model for water use, resulting in waste, over-consumption and the deterioration of watercourses.

New, progressive water laws now consider water left in rivers and streams to be a “beneficial use”, meaning water may be restored to rivers and streams without forfeiting the landowner’s water rights.

In response, in 2009 the Bonneville Environmental Foundation (BEF) created Water Restoration Certificates (WRCs), to provide an economic incentive for water rights holders to contribute to restoration efforts.

The Great Experiment

In his best-seller, Simon Winchester recounted the re-population of Krakatoa with primary species after a tectonic event, saying that researchers labelled the area, “arid and seemingly death-filled.” Then, “within months an abundance of life- and that almost certainly included at least the modest sufficiency of flies required to satisfy a small army of spiders- began to return to the islands, in earnest.”

Does this sound familiar… life returning in many forms to resettle the Colorado Delta and its estuary? It can happen. It does happen.

Admittedly, in the case of the delta, man has become involved in order to provide the water for the secondary succession in what is termed dam reoperation. And when man is involved there is the added need for a willingness to listen:  the-political feasibility in face of sharp competition for water (drought) was epic in this case.

Water-Sharing Model

So, how can this be a model for water-sharing agreements elsewhere in the Colorado River Basin, and beyond? As Jennifer Pitt of the Environmental Defense Fund (EDF) points out in an article entitled Restoring the Colorado River Delta, “we just need to apply the lessons learned from the delta.” In other words, figure out how much water the area needs, create incentives to protect that level of water use in cities, and create incentives to protect that level of water use on farms and ranches.

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