Watered Down

Watered Down

This story comes from Headwaters Magazine, the quarterly publication of the Colorado Foundation for Water Education. It’s definitely what I call a water wonk piece, but if ever someone wanted to know more about how states manage (or ought to manage) groundwater resources, Colorado is a good state to learn from.

Water Underground

Optimizing Use of an Unseen Resource

Headwaters Magazine, Summer 2009

By Joshua Zaffos

Growing up on his family’s ranch along the Rio Grande River near Alamosa, Ken Knox got an early education in the contentious field of groundwater use. The San Luis Valley is a high-altitude desert that averages just 7 inches of precipitation a year, so every drop of water—from the sky or the ground—is precious. Knox recalls neighbors fighting over rights to one-quarter of a cubic foot per second of water, equal to about 180 acre feet per year. The argument landed in court, and by the time it was resolved, the only way the families could pay off their legal bills was to sell their land.

csu1948-sprinkling1From ranch kid to chief deputy state engineer, Knox has spent much of his life thinking about groundwater. Today, after 24-plus years in the Colorado State Engineer’s Office, Knox works for URS, a private engineering corporation.

“The development of every set of [groundwater] rules is incredibly complex,” Knox says, “because you’re talking about people’s livelihoods.”

There’s another reason groundwater administration is complex—the movement and replenishment of groundwater itself is complex. The Rio Grande Basin, for instance, sits in a rift valley with multiple aquifer systems. One is a deep, confined source that runs more than 1,000 feet below the surface. There are also relatively shallow alluvial aquifers that feed into the Rio Grande and Conejos rivers. And there is a shallow, unconfined aquifer in a closed basin. These sources are all partially interconnected, and their interactions must be understood to provide accurate administration.

The movement of groundwater in other river basins, like the Arkansas and the South Platte, isn’t quite as complicated, but determining the impacts from groundwater use on stream flows is hardly straightforward. Figuring out how to simultaneously protect senior water rights, meet interstate compact conditions and utilize groundwater resources is no simple affair, legally or hydrologically.

“There isn’t a rule of thumb” when it comes to groundwater administration, says water attorney David Robbins, who has represented the State of Colorado in river compact litigation and groundwater users in additional court proceedings. Groundwater administration has developed by “fits and starts,” a function of science and technology, nature and necessity, Robbins adds. “It’s sort of a coming-of-age story.”

Tapping Wells and Passing Laws

Groundwater regulation was something of an administrative afterthought until 1953, when the Colorado General Assembly passed the Underground Water Act. Up until that time, when someone wanted to drill a well, they just went ahead and did so without much consideration of its effects on the underlying aquifer or nearby stream. From 1953 until 1957, the law stipulated the Colorado Water Conservation Board would issue well permits. Although the CWCB required well drillers to file a license, it was more of a registration system than any meaningful regulation.

Four years later, the 1957 Colorado Ground Water Law put the State Engineer’s Office in charge of these permits and acknowledged that a well license was not a water right, but only a permit to drill the well itself.

Despite these first steps at administration, water users with senior surface rights in the Arkansas, South Platte and Rio Grande basins faulted the expansion of groundwater use, a response to drought and lower stream volumes, for depleting river flows. Studies backed these assumptions, but there was little regulatory muscle to effectively manage the impacts.

The state legislature responded by passing the 1965 Ground Water Management Act, which provided new laws for application procedures and an injury evaluation standard for high-capacity wells. For the first time, state law enabled the State Engineer to consider—and potentially deny—well applications on the basis of injury to senior surface water rights. The law recognized the tributary connection between surface and groundwater in certain basins, a major hydro-legal epiphany that still makes Colorado stand out among other states. The law also created the Ground Water Commission, which could declare Designated Basins where surface water is scarce and/or groundwater is the predominant source of water. There are currently eight Designated Ground Water Basins in Colorado.

A few years later, the 1969 Water Rights Determination and Administration Act represented another advancement in the state’s groundwater administration. Kevin Rein, assistant state engineer for intrastate water supply development and litigation, says the 1969 law is significant for two reasons: It recognized that previous laws did not adequately address injury to senior water rights holders, and it established augmentation plans as the preferred avenue for allowing out-of-priority groundwater pumping under the prior appropriation system, which orders both the use of surface flows and groundwater.

According to Rein, augmentation plans include terms and conditions for obtaining groundwater while protecting against the depletion of river flows that could affect senior water rights. The plans demonstrate how much water will be pumped and consumed and how much will be returned to an aquifer or stream. Each plan must be approved by the water court and stand up to any individual objections.

The state continues to tweak its groundwater administration, but the framework developed in the 1960s still guides tributary groundwater use today.

Nontributary groundwater, on the other hand, has minimum or no connection to surface flows and is mostly regulated by state statutes adopted between 1973 and 1985. Those rules allow landowners to use nontributary resources, including those within the Denver Basin, at a rate of 1 percent a year for 100 years to pace the depletion. Additionally, the Ground Water Commission regulates non-tributary groundwater as designated groundwater if it’s within a Designated Basin.

“I really applaud Colorado,” says Knox, “because even in that time [dating back to the 1950s], they said we need to manage these resources for the future, in balance with economic development. We are literally decades ahead of some of our surrounding regions.”

Compacts and Models

Just as Colorado was hammering out its groundwater policies, another challenge presented itself. In 1966, the states of Texas and New Mexico sued Colorado because it was failing to meet the conditions of the 1938 Rio Grande River Compact. The interstate compact divides the annual flows of the Rio Grande between the states it runs through, and Colorado must ensure its downstream neighbors receive their allocated flows. Other compacts also dictate the use of river flows—and groundwater—in the South Platte, Arkansas and Republican river basins.

Water users in the upper Rio Grande began drilling more wells during the 1950s drought to supplement diminished flows in the river and its feeder streams. The fulfillment of senior surface rights and the increased use of groundwater meant Texas and New Mexico weren’t getting their legal share of water. Later lawsuits—by the state of Kansas with regard to Colorado’s overuse in the Arkansas River Basin and by Nebraska in the Republican River Basin—made similar claims.

“We had no rules or regulations that dictated use of groundwater up until that time,” says Steve Vandiver, manager of the Rio Grande Water Conservation District in Alamosa and a former division engineer for that region. “The science hadn’t really caught up to us.”

A tangle of legal action ensued over the following decades—and continues today—to determine the connections between groundwater and surface flows. The State Engineer’s Office instituted a 1972 moratorium on new wells in the unconfined aquifer that feeds into the Rio Grande and Conejos rivers. Well drillers targeted the deep, confined aquifer until another moratorium was put in place in 1981. Small, home wells were exempted from the ban.

Legal and regulatory fixes were limited by the understanding of the Rio Grande Basin’s intricate hydrogeology, Vandiver says. “Impacts are not one-for-one,” he adds, meaning that tapping an acre foot of groundwater from a well in the Rio Grande Basin won’t directly deplete an acre foot from the river.

Engineers worked to develop groundwater models, both to determine what was going on underground and to figure out how to address depletions for users in Colorado and downstream.

Groundwater modeling, however, remains an evolving science and perhaps something of an art. Prior to the 1980s, electric analog models replicated aquifers using plywood fitted with a grid of resistors to simulate flow and capacitators to simulate storage. Computers replaced paper spreadsheets and slide rules in the 1980s, and modeling went digital, providing a more sophisticated understanding of groundwater’s movement.

“The parallel with the technological advancement is the need to have more effective groundwater management tools,” says Knox.

Not that computer models have prevented groundwater administration from being debated in courtrooms. The U.S. Supreme Court has had to settle disputes over water use and depletion according to the compacts for the Rio Grande, Arkansas and Republican. South Platte water users in Colorado have looked to the courts to handle in-state quarrels. That’s because on top of all of the legal bounds, there is another great limiting condition, Knox says: “We live in a dynamic hydrologic environment.”

Drought and Disruption

Drought initiated the first wave of Colorado groundwater regulation half a century ago, and dry times are influencing current management.

Compared with the hydrology of the Rio Grande region, the South Platte is a pretty simple system. Robbins describes the river as “a trough in bedrock,” meaning it’s a shallow and fairly narrow stream with water moving relatively easily between the ground and the channel. As a result, well drilling has a direct impact on river flows.

Farmers and others along the South Platte have relied on groundwater for several decades. Some users had obtained decrees for augmentation plans, but Ground Water Appropriators of the South Platte and others relied on annual substitute supply plans. Both water court-approved augmentation plans and State Engineer-approved substitute water supply plans aim to ensure that depletions caused to the river by well pumping are replaced by some other source of water. That became a front-and-center problem when the 2002 drought kicked in, and surface and groundwater flows couldn’t measure up to past uses.

In 2001, the Colorado Supreme Court decided the State Engineer didn’t have the authority to approve substitute water supply plans, ruling that plans for replacing depletions to the stream system must be approved by the water court. Known as the Empire Lodge case, the decision forced groundwater users in the South Platte and other basins to obtain approved plans of augmentation or shut down their wells, says Robbins. The state legislature later passed a law allowing the State Engineer to approve substitute water supply plans if an augmentation plan is concurrently filed in water court, but hundreds of farmers have essentially lost their ability to legally pump their wells, wreaking havoc on communities in the South Platte Basin.

Rio Grande groundwater users have also suffered since 2002, Robbins adds, “but we’re trying to avoid the economic destruction and social dislocation” that has occurred on the South Platte. To that end, users have discussed buying out existing wells while preventing the drilling of new wells to create sustainable aquifer conditions. “Our job is to solve the problem in the least disruptive way,” Robbins says.

Groundwater Management Matures

In the Arkansas River Basin, resolution trumps disruption these days, according to Robbins. After Kansas sued Colorado over the Arkansas River Compact in 1985, a decades-long court battle ensued until the U.S. Supreme Court backed Kansas’ claims of depleted flows. Well-measurement rules followed, to monitor Colorado groundwater users’ impacts on river flows.

Like the South Platte, the Arkansas is an alluvial stream where groundwater depletion can be directly detected in lower surface flows. All groundwater users there are now required to have plans to replace depletions resulting from groundwater use, and group associations have formed to lease augmentation water supplies from cities and other water districts.

Groundwater use in the Arkansas Basin has undergone “intense scrutiny,” Robbins says, due to the compact litigation and subsequent regulation. “The rules have been successful.”

In the Rio Grande Basin, Vandiver describes the region as still “maturing in the groundwater arena.”

Surface and groundwater users have spent decades in court, and Vandiver says engineers have finally devised a computer model that accounts for the complex relationship between groundwater use and surface flow depletion there. Groundwater users have developed a plan of water management—instead of a plan of augmentation—that will enable many current well operators to continue pumping while guarding against injury to senior surface flow rights. After a degree of encouragement, some users have agreed to cease their water consumption, and managers will measure impacts to surface flows.

Vandiver says the Rio Grande district will also create its own subdistrict to manage wells locally. The subdistrict should enable more flexibility and hopefully prevent well curtailment from being the primary means of regulating groundwater use. If it’s a successful model, the district would form other subdistricts, but so far surface water users have objected to the plan and are in court to make sure the priority system is enforced. The maturation process continues.

Recently, the State Engineer’s Office has fielded an increased number of requests to mine or utilize geothermal resources, says Rein. In some cases, projects will remove water while others might return flows but at different temperatures, so the state must determine what constitutes an injury to other water users. The small but growing industry is a prime example of how and why groundwater administration will continue to adapt and change.

“It’s the right thing to do,” says Knox, of the continuing efforts to refine groundwater administration, “to optimize use of this resource for short-term gain and long-term benefit.”

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