Mexico and the United States Assume a Legal Duty to Provide Colorado River Delta Restoration Flows: An Important International Environmental and Water Law Precedent

• DOI: http://doi.org/10.1111/reel.12066
• Published date: 01 April 2014
• Date: 01 April 2014
• Author: A. Dan Tarlock

Mexico and the United States Assume a Legal Duty

to Provide Colorado River Delta Restoration Flows:

An Important International Environmental and Water

Law Precedent

A. Dan Tarlock

In 2012, Mexico and the United States interpreted a

treaty allocating the use of the Colorado River to

protect a stressed delta in Mexico by establishing a

pilot programme delivering a base flow to the Delta.

Minute 319 is a possible first step toward a permanent

adaptive management regime for the Delta because it

sets three important international water and environ-

mental law precedents. First, it is a de facto implemen-

tation of the ecosystem conservation mandates of the

United Nations Convention on the Law of the Non-

navigational Uses of International Watercourses.

Second, Minute 319 is equally recognition of the

emerging duty of riparian States to cooperate in the

long-term management of shared rivers. Third,

although Minute 319 was the product of sovereign-

to-sovereign negotiations, it was made possible

by nongovernmental organizations (NGOs). It thus

illustrates the important role that NGOs can play in

the implementation of international environmental

and water law.

INTRODUCTION

Mexico’s Colorado River Delta is one of the world’s

many stressed deltic aquatic ecosystems.1The Colorado

originates in the Rocky Mountains in the United States,

enters Mexico at the Arizona-California border and

drains into the Gulf of California (Figure 1). A 1922

Interstate Compact among seven federal states in the

United States and the 1944 Mexico-United States Water

Treaty allow users in both nations to divert the entire

average flow upstream from its mouth, thus cutting off

both the necessary seasonal sediment deposits and

water flows to sustain the Delta. Until 2012, the two

nations had no treaty obligation to supply any flows to

the Delta; remnant marshes survived precariously on

wet year surplus ‘pulses’ and upstream agricultural

return flows. For years, both Mexico and the United

States both took the position that the degradation of the

Delta was an unremedial consequence of the Treaty.

This position was consistent with both the Treaty and

customary international water law, which does not rec-

ognize a nation’s right to the pre-dam flow of a river.2

But, after a two-decade-long campaign by nongovern-

mental organizations (NGOs) to protect the Delta, in

2012 the two countries de facto amended the Treaty to

provide a modest experimental Delta flow maintenance

regime.3

The de facto amendment, Minute 319,4is an important

international water and environmental law precedent,

although it makes no mention of any principle of inter-

national water or environmental law, and expressly

states that it does not set a precedent for future

1T. Bucx, M. Marchand, B. Makaske and C. van de Guchte, Com-

parative Assessment of the Vulnerability and Resilience of 10 Deltas-

Synthesis Report (Delta Regional Alliance, 2010); J. Coleman, O.K.

Huh and D. Brand Jr., ‘Wetland Loss in World Deltas’, 24:1A Journal

of Coastal Research (2008), 1. The world’s stressed deltas from

upstream development include, inter alia, the Mekong (see D. Biggs,

‘Fixing the Delta: History and Politics of Hydraulic Infrastructure

Development and Conservation in the Mekong Delta’, in: M.A.

Stewart and P.A. Coclanis (eds), Environmental Change and Agricul-

tural Sustainability in the Mekong Delta (Springer, 2011), 35; I.C.

Campbell, The Mekong: Biophysical Environment of an International

River Basin (Academic Press, 2009)); the Mississippi (see J.W.

Jacobs, ‘Comparing River Basin Experiences between the Mekong

and the Mississippi’, 24:3 Water International (1999), 196); and the

Niger (see T.K.S. Abam, ‘Regional Hydrological Research Perspec-

tives in the Niger Delta’, 46:1 Hydrologic Sciences (2001), 13).

2Lake Lanoux Artibration (France v. Spain), [1957] 12 RIAA 281. See

O. McIntyre, Environmental Protection of International Watercourses

under International Law (Ashgate, 2007).

3As explained below, the Treaty allows the parties to record subse-

quent interpretations of the Treaty as Minutes. These Minutes are in

effect amendments and are widely referred to as such. I have chosen

to use the term ‘de facto amendment’ to signal that Minutes are

technically only interpretations.

4International Boundary and Water Commission, Interim Interna-

tional Cooperative Measures in the Colorado River Basin through

2017 and Extension of Minute 318 Cooperative Measures to Address

the Continued Effects of the April 2010 Earthquake in the Mexicali

Valley, Baja California (Coronado, 20 November 2012) (‘Minute 319’).

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Review of European Community & International Environmental Law

RECIEL 23 (1) 2014. ISSN 2050-0386 DOI: 10.1111/reel.12066

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