Monday, Jan 8 (2018), marks the first day arguments will be heard before the Supreme Court of the United States (SCOTUS) in the decades-old water dispute between Texas, New Mexico and Colorado.

The event marks a milestone for legal representatives from Texas who first filed a lawsuit back in 2014 claiming New Mexico allowed diversions of surface water and the pumping of ground water that was intended for Texas' use by a long standing tri-state treaty, namely, the 1939 Rio Grande Compact.

According to that agreement, Colorado, New Mexico and Texas agreed to protect the integrity and operation of the Rio Grande Project, which ensures the shared rights of the Rio Grande between the three participating states. The Rio Grande headwaters originate in Colorado, flow downstream through New Mexico and then into Texas, terminating at the river's mouth where it flows into the Gulf of Mexico.

The river has long provided a source of water to sustain communities, industry and agriculture down its 1,885 mile journey from the Rocky Mountains to the Gulf. It is the second longest river in the United States, surpassed only by the length of the Mississippi River.

In modern times, the river provides water to cities and rural communities in all three states, including El Paso, Texas, which uses those waters for over 50 percent of their total water needs. Agricultural operations down the length of the river also depend on its water for irrigation in the arid and semi-arid environment of the Greater Southwest.

Related:Agriculture tells the history of the Rio Grande Valley

ORAL ARGUMENTS

During the session scheduled Monday, attorneys will present oral arguments before the Court. The total session time before Justices will be limited to only one hour and is expected to be the first of many sessions as the case moves forward.

Legal Counsel for Texas, the plaintiff in the case, are set to argue the merits of their case against the State of New Mexico, and legal counsel from New Mexico, the defendant named in the lawsuit, are expected to argue that the terms of the Rio Grande Compact were not violated because population growth below the appointed containment reservoir – Elephant Butte – is located upstream of the areas in New Mexico that have experienced greater populations numbers and expansion, requiring elevated needs for more water.

According to the Rio Grande Compact, New Mexico's obligation of water hinges on collecting enough water in Elephant Butte Reservoir to supply Texas its fair share as outlined in the agreement, and to provide water to Mexico as agreed in a U.S./Mexico International Water Treaty.

In a legal brief filed by Texas, "The State of New Mexico has allowed and authorized the diversion, extraction and use in New Mexico of Rio Grande Project water that has been allocated to Texas. These diversions, extractions and use include Rio Grande Project return flows and other underground water that is hydrologically connected to the Rio Grande, and to which the United States has superior rights, including the right to deliver that water to Texas."

Texas alleges New Mexico has repeatedly violated its obligations under the compact by allowing diversions of surface and underground water below Elephant Butte Dam, which depleted the water available to users in Texas.

But attorneys for New Mexico claim in response to Texas’ concerns that pumping underground water in southern New Mexico is not affected by the Rio Grande Compact and it has no obligation to ensure Texas’ allocation of water at the New Mexico-Texas state line. They further argue the agreement with Texas was not in violation of the Rio Grande Compact because the agreement does not require the state to prevent development downstream of Elephant Butte.

 The Texas Attorney General's office asserts "“The Rio Grande is the primary, at some places the only, source of supply for agricultural lands within Texas that are the intended beneficiaries of Texas’ allocation of Rio Grande water."

The Texas AG (at the time the suit was filed was now-Texas Governor Greg Abbott) argued that "so long as New Mexico refuses to acknowledge its Rio Grande Compact obligations to Texas, no amount of negotiation or mediation can address Texas’ claims. Furthermore, so long as the matter continues to be unresolved by the court, New Mexico can simply continue to divert, pump and use water in excess of Rio Grande Compact apportionment, and capture Rio Grande Compact water allocated to Texas, to the direct, immediate and irreparable injury to Texas."

New Mexico had asked the High Court to dismiss the lawsuit, but that motion was denied.

In 2014, a special master, A. Gregory Grimsal of Louisiana, was assigned to the case to look into the claim and to report his findings to SCOTUS. Monday's hearing was scheduled based upon his conclusions and objections to that conclusion by New Mexico officials.

The hearing Monday in the original jurisdiction dispute will focus on exceptions filed by the United States, which intervened in the case, and New Mexico to the master’s first interim report.