The Rio Grande Compact: Steven E. Vandiver started with the Colo- Its the Law! rado Division of Water Resources in 1973 as a hydrographer-in-training in Denver. He came to Alamosa as a hydrographer shortly thereafter and continued to move up through the ranks as Lead Hydrographer, Dam Safety The Adminis- tration of the Engineer, and Assistant Division Engineer. Rio Grande In 1981, Steve assumed the responsibilities of Compact the Division Engineer for Division 3, the Rio in Colorado Grande basin in Colorado. Steve, as Engi- neer Adviser for Colorado, was involved in the administration of the Rio Grande Com- pact and the Costilla Creek Compact. He was also a member of the Rio Grande Silvery Minnow Recovery Team. Steve holds a bachelors degree in civil engineering from the University of Colorado, Boulder and is a registered professional engineer. The Administration of the the Compact and still meet her obligations to the Rio Grande Compact downstream states. Since 1939, the administration of the Rio in Colorado Grande Compact in Colorado has been an evolutionary process marked by three distinct periods. The first period from 1939-1967 was a time when Colorado officials made the decision to INTRODUCTION continue with the administration of water rights as they had during the study period of 1927 to 1936. The Rio Grande Compact requires Colorado This action worked well until 1952 when to deliver certain amounts of water annually to the Colorado under-delivered approximately 154,000 stateline according to the delivery schedules in acre-feet. The reasons for this under-delivery are Article III. On any given year this can require largely unknown, but it began a period of under- from 25 to 50 percent of the water generated in deliveries and accrued debit that continued until the Rio Grande and Conejos River basins to 1967 when that accrued debit reached approxi- arrive at the Lobatos gage just above the border mately 940,000 acre-feet. The year before, in with New Mexico. Since the diverters have the 1966, the states of Texas and New Mexico had capability of diverting and using most of the water brought an action against Colorado in the U.S. generated in both basins, it is necessary that a Supreme Court to force Colorado to comply with process be in place that enables Colorado to the provisions of the Compact. In May of 1968, ensure that her obligation is met. One can imagine the Court granted the three states and the U.S. a the turmoil that can be generated when water is stipulation for continuance of the case as long as bypassed to the stateline when there is a Colorado met her Compact obligation until she significant demand for that water in Colorado was once again in compliance. from the water rights owners on the rivers. A The second period, from 1968 to 1985, great amount of work was required by the State of Colorado administered the Compact pursuant to Colorado and the water users in the San Luis the stipulation and was forced to determine a way WRRI Valley to reach an administrative scheme that to curtail water rights in a manner that would Conference allowed Colorado to use her entitlements under allow the appropriate delivery of water to the Proceedings 1999 1 The Rio Grande Compact: Lobatos gage near the stateline. Since this PERTINENT COLORADO WATER LAW Its the Law! administrative scenario had never been attempted, the Colorado State Engineer entered a very When the State of Colorado achieved difficult time of working with the water users on statehood in 1876, her corresponding constitution both the Conejos River and the Rio Grande to included and adopted the Doctrine of Prior determine how this issue might be resolved. In Appropriation as the basis for the appropriation The Adminis- 1975, after several years of negotiated informal of the water. This was a matter of necessity due to tration of the annual operative criteria, the State Engineer the water-short characteristics of many of the Rio Grande promulgated rules and regulations for the streams in the State. It was recognized early on Compact intrastate administration of the Compact on each that because of the large numbers of competing in Colorado river and between the two rivers. In 1979, the appropriations that some judicial confirmation numerous protests to the proposed rules were would be required to allow for the orderly heard in the local District Court in an eleven-week distribution of the States water. It was also trial. The decision rendered by the Court upheld authorized by the legislature in 1883 that a State the State Engineers Compact rules but the ruling Engineer would be given the responsibility to was appealed to the Colorado Supreme Court. administer the water rights of the State. The Supreme Court decision upholding the State As early as 1883, general adjudications were Engineers rules was made in 1983. Therefore, held on the Conejos River that confirmed and from approximately 1968 to the present, the decreed water rights in relative priority based on Colorado State Engineer has directed that the the date of appropriation and the amount required Compact be administered as a two-river system to satisfy the irrigation requirements under each with each river responsible for its own delivery ditch. The first general adjudication that occurred obligation dictated by Article III. The rules also on the Rio Grande mainstem was signed on May provided that any curtailment of diversions would 1, 1896. These adjudicatory processes were come from the junior water rights, which would widely noticed and all individuals who had have otherwise been in priority on any given day completed their appropriations were allowed to of administration. During this period of litigation come forward and provide proof of their claims. over the rules, Colorado met or exceeded its The date of appropriation, the legal description of obligation each year from 1968 through 1984 the point of diversion, the flow rate of the because of the incentive provided by the U.S. appropriation, and the use to which the water Supreme Court stipulation. In fact, because of the right was to be placed was determined by the hydrologic and climatologic vagaries of the Upper court and confirmed. The court referee Rio Grande Basin, coupled with the negative investigated each claim for accuracy, ranked the consequences of noncompliance with the water rights according to the appropriation dates, stipulation, Colorado was forced to over-deliver and recommended the court decree them to ensure that she met the obligation. This very accordingly. The State Engineer, through water conservative administration resulted in a reduction commissioners, used these decrees to administer in the accrued debit of approximately 430,000 and deliver the available water to those who were acre-feet in 17 years. entitled to it. Subsequent supplemental The third and current period began in June of adjudications would include all new or existing 1985, when the Rio Grande Project in Southern claims not previously decreed and create additions New Mexico spilled and eliminated the debt of to the water rights administrative list. All water Colorado and New Mexico. This gave cause for rights in these subsequent adjudications were the three states to recommend to the U.S. junior to all previously adjudicated rights Supreme Court that the 1966 case be dismissed, regardless of their appropriation date. Therefore, which it was on December 9, 1985. Since 1985, a water right may have a very early appropriation Colorado has operated under the Compact as it date, but having failed to participate in the was written and has met or exceeded its obligation original adjudication, would end up junior to all since that time. What is required to accomplish others in the original adjudication. this administration is the topic of this paper and The following table describes the adjudication WRRI will be described in detail below. dates and the amounts decreed in each on the two Conference Proceedings 1999 2 The Rio Grande Compact: Compact streams in Colorado. The Conejos well as the State to acquire real-time data in order Its the Law! adjudications include the Los Pinos and the San to ensure better administration. Antonio rivers because they are tributaries. It is readily apparent that the vast majority of the HYDROLOGY OF THE RIO GRANDE AND water available in both systems was decreed by CONEJOS RIVER around the turn of the century. The hydrology of The Adminis- the two basins described later in the text will show The headwaters of the Rio Grande mainstem tration of the the grossly over-appropriated nature of the two and the Conejos River are ringed by the Conti- Rio Grande streams. nental Divide. This area of southwestern Colorado Compact normally receives a significant snowpack that in Colorado Rio Grande Conejos River provides the majority of the water that arrives at and tributaries and tributaries the upper index gages on the two rivers. These headwater areas are in relatively close proximity 1896: 3209 cfs 1883: 1459 cfs to the index gaging stations near Del Norte, 1903: 2501 1890: 1312 Mogote, and Ortiz. Normally, the days snowmelt 1916: 678 1914: 502 or rain event runoff arrives at the gages during the 1934: 353 1915 to present: 375 next 12 to 24 hours, depending on what location 1959: 765 in the basin one might consider. Since the 1960 to present: 140 operating reservoirs on both systems control only a fraction of the flow, the flows at the index gages Total including instream flow: are primarily a reflection of snowmelt and rainfall 9139 cfs 4104 cfs events. All these reservoirs hold relatively junior priorities and during the runoff, the reservoirs These adjudications established early on the store under those decrees on a very limited basis system of administration that has followed for when the flows at the index gages are very large.