Staring into New Mexico’s Water Supply Abyss

Water managers along the Middle Rio Grande (MRG) and across New Mexico increasingly feel as if they are staring into an abyss of water shortages for increasing numbers of users who depend on water supplies for drinking, for economic growth, and even for the survival of our present-day economy. 

The reliable supply of NM’s surface water to our streams, rivers, lakes, irrigation systems, and other critical water needs depends primarily on winter and early spring accumulations of mountain snow. 

As we have experienced in recent years, climate warming increasingly causes the over-winter loss of snowpack, markedly reducing the total annual water supplies available and causing snowmelt runoffs earlier in the spring before crops have had sufficient time to develop to when they could benefit from earlier watering. 

Couple these changes to the long tendency along the Rio Grande and across NM to over-use surface water supplies. For example, early in the 1800s the annual water supply of the Rio Grande was declared to be fully allocated. Then, with the drought of 1888, it was then declared to be over allocated, a condition that is unchanged today. And we have added more and more water users over time. 

With climate warming also producing changes in global atmospheric circulation patterns, future projections forecast that NM will become increasingly dryer due to total region-wide reductions in snowpack and increased water loss due to increasing evaporation rates. 

In an attempt to have equitable water supplies from the Rio Grande for Colorado, New Mexico, and Texas, as well as addressing US treaty requirements to Mexico, the three states signed the Rio Grande Compact, which was then ratified by Congress in 1939. 

Today, the claim that NM is and has long been shorting the agreed-to water supply deliveries to Texas is awaiting a final US Supreme Court decision. The original terms of the Compact effectively caused additional limits on the surface water supply available to MRG users.  The final court decision might further constrain the MRG supply.

To fill the gap in limited surface water supplies, communities and individuals have increasingly depended on pumping groundwater to address their need for water. Today, many of NM’s groundwater aquafers are nearing depletion. 

MRG water supplies have been augmented by diversion of water from the San Juan River in the upper Colorado River basin into the Rio Chama and then into the Rio Grande. Here it is important to recognize that the effects of climate warming are similarly affecting water supplies across the entire southwest into California as the Colorado River and San Juan River are seeing reduced volumes as well. 

Multistate negotiations on how climate-driven water supply shortages from the Colorado river will be distributed to all of the affected southwest states are ongoing with no permanent plan in sight. How that final future plan will affect San Juan River diversions to the Rio Grande is unknown, but in recent years that diversion has been short of the originally anticipated supply. 

How best to address the increasing water supply shortages across NM is an open question. 

Can the many and different water users within each of NM’s river basins and water management areas somehow reach agreements on how best to equitably share these shortages, as has become the custom for over 100 years along NM’s acequia communities? 

As a start, the Water Advocates for NM and MRG are working with water managers along the MRG, including the NM Interstate Stream Commission, the MRG Conservancy District, Bernalillo County, ABCWUA, the US Bureau of Reclamation, and others to start planning for our shortened mutual water supplies. 

The NM Interstate Stream Commission is hosting several Water Planning Open Houses to hear water related concerns from communities across the state as first step to draft the rules and regulations for updated regional water planning. We encourage you to attend these meetings and make your voice heard. Without accurate information and community engagement, the abyss will only grow. Let’s back away from the abyss and create a sustainable water future for New Mexico and the Middle Rio Grande.