Here we illustrate an approach for evaluating how much water stewardship activity is likely needed to close the “sufficiency gap,” using local data compiled for both a river in the western USA and an aquifer in Mexico. These examples are based on the logic that when there’s an inadequate amount of water to meet a community’s needs or desired conditions, some existing uses of water will need to be reduced or the proportion of water available to each user, sector, or the environment will need to be rebalanced to attain the desired conditions. Again, we acknowledge that resolution of these issues will oftentimes exceed a local water community’s means or capacities, and governing agencies responsible for water allocation or infrastructure development will need to be involved in many instances. But considerable momentum and problem definition can be achieved at the local community level.

Figure 6 below graphically summarizes the overall water budget of the Colorado River basin in the western US. This water budget was prepared using a variety of published data sources and a river system model developed by the US Bureau of Reclamation. As illustrated here, it is clear that irrigated agriculture accounts for the largest portion of water withdrawals and consumptive uses in this large river basin (637,000 km2). Another important point about this water budget is that all of the available water is fully consumed before the river reaches its delta in Mexico, in virtually every year. The lack of any ‘reserve’ of water left to flow through the delta has severely damaged freshwater and estuary ecosystems, disrupted indigenous cultures dependent on wild plants and animals for sustenance, and created substantial risks for businesses, farmers, and all other water users during years with less-than-average water availability. There is a strong desire to restore some of the water flow through the delta to support ecosystem, economic, and cultural needs locally.

Colorado River: Water Withdrawals and Consumptive Uses

This diagram depicts the natural water supply, use, return flow, and consumptive loss of water in the Colorado River watershed. The far left side of the diagram indicates the average volume of water in the river and in underground aquifers that is renewed by rain and snow annually. This renewable water is withdrawn and used for various purposes, with some portion of the withdrawn water being consumptively used (depleted) and some returning to the river after use. Before reaching the river’s delta in Mexico, all of the water has been consumed.

The water budget portrayed in Figure 6 provides important context for understanding the types of water uses that have led to the ecological, social, and economic impacts experienced today in the Colorado River delta. Prepared at the scale of an entire river basin, such a water budget can also provide insight into regional- or national-scale water policies that may need to be reformed, such as changes in water allocation policies (e.g., “use it or lose it” provisions) at state or federal levels that discourage water conservation in agriculture. Water governance adjustments at state or national scales can be powerful drivers for changes in water use throughout a large river basin such as the Colorado, and can thus be quite influential in mobilizing changes in water use that can help realize the attainment of desired conditions within an entire region. For example, the Commonwealth government in Australia in 2012 adopted a basin-wide plan for the Murray-Darling Basin that mandates a 30% reduction in consumptive use of water across that river basin. Private interests, including associations representing an entire water-sector (e.g., the Farm Bureau often represents the water interests of farmers in the US), can contribute to discussions about needed policy changes.

However, many companies will understandably shy away from playing a highly-visible role in largescale water policy changes, and may prefer to focus on more localized engagement where they can participate in a more tangible way. For example, a number of companies recently contributed financially to an effort to help local communities and NGOs to determine how much water flow would need to be restored to the Colorado River delta to regain some semblance of ecological health. Scientists estimated that unmet water needs for environmental support total approximately 124 million cubic meters per year, on average.

Following a review of the local water budget of the delta region, it was determined that the needed return of water to the delta ecosystem could be achieved through on-farm water conservation practices or the purchasing of water rights from farmers, thereby moving water out of the agricultural component of the water budget and into an ecosystem component that does not presently exist in the water budget as illustrated in Figure 6.

A number of companies also contributed to a monetary fund managed by multiple conservation NGOs (the “Colorado River Delta Water Trust”) for the purpose of purchasing water rights to benefit the delta’s ecosystem. In March 2014, the water rights purchased by the Trust were used to create the first “pulse release” of water from upstream reservoirs into the delta. This pulse release provided water to the delta for the first time in decades. This restoration project has been very well-received by local communities, NGOs, and the farming community, and has garnered considerable publicity and recognition for the companies that helped support the project.

El Bajío is a key agricultural and industrial hub in Mexico and one of the fastest growing areas in the country. Its central location, healthy soils, year-round growing climate, and easy transportation access to both coasts as well as north to the U.S. and south to Central America, make it a very attractive location for national and international investment. El Bajío boasts more than 400,000 hectares of prime quality, irrigated agricultural land that produces a wide variety of agricultural products, including grains, vegetables and fruit. The region is Mexico’s top producer for canned and frozen produce and is responsible for 90% of Mexico’s exports in frozen produce. However, this region is experiencing considerable water strain, as irrigation is essential to grow crops in this semiarid region, and a rapidly growing manufacturing industry and urban population need ever-increasing volumes of water.

The El Bajío region overlays multiple adjacent aquifers that provide water for growing high value crops such as fruit and vegetables, and for supplying manufacturers and cities, but the water budgets for these aquifers (prepared by the national water agency CONAGUA) reveal that they are being pumped at a rate that is far outpacing annual replenishment. Aquifer levels across the state of Guanajuato are declining at an average annual rate of 2 meters per year, with some locations declining by as much as 5 meters per year.9 If water use continues as it has, scientists estimate that for many of the aquifers underneath El Bajío it will become too expensive, or the water of too poor quality, for pumping to be feasible beyond 20 more years.

Mexico has a ground water rights permitting system, but neither the location nor the volume of pumping are strictly enforced, mainly due to inadequate public sector capacity. As shown in Figure 7, even as the state set a moratorium on well drilling, the number of new wells continued to grow illegally. There are limited economic incentives for growers to increase the efficiency of their water use. Under Mexican law, water is free for agricultural purposes and, until recently, the Mexican government has subsidized electricity for irrigation groundwater pumping. Finally, even though technology to enable more efficient irrigation is readily available, it has been implemented on a very limited basis in the region.

Figure 7. Number of wells in Guanajuato over time as compared to well drilling prohibition orders

In order to reverse this trend, collective action efforts must address the management, economic, and technology challenges the region faces. Fortunately, the “sufficiency gap” that needs to be addressed to arrest groundwater declines has been determined by a state-supported groundwater user group, based on a water budget of the aquifers. For example, in the Irapuato-Valle de Santiago Aquifer, there is an average annual deficit (replenishment minus water use) of 255 million cubic meters per year. To be “sufficient”, the combined impact of a suite of water stewardship activities would need to account for this gap, and aim to replenish water at an even greater rate for several years until the volume of water in the aquifer is returned to historic levels (Figure 8).

Figure 8

An example of water stewardship strategy development based on a suite of solutions aiming to meet a specific sufficiency goal. Each color represents a different strategy, and the cost in each box simply illustrates how one may employ a combination of different solutions, at different costs per cubic meter of water saved or replenished, to meet the goal.

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