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Colorado's public lands are faced with new challenges but water and land management depend on working together. Read about the relationship between water and land in Colorado and how Coloradans are converging to restore Colorado's public lands in the Spring 2018 issue of Headwaters magazine.

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Water Education Colorado

A Numbers Game: what the technical work surrounding the Interbasin Compact Process reveals

By Eryn Gable

As Colorado heeds forecasts that its communities and industries are outgrowing water supplies, both water providers and users have come to the table to lay down their cards. In order to play their collective hands wisely, they are hard at work putting everything down on paper. Painstaking evaluations and number-crunching may prove integral to future decision-making.

To coordinate planning and facilitate various studies, the Colorado Legislature established the Interbasin Compact Process, a forum which includes a broad range of stakeholders and confers a greater degree of influence to people living throughout the state's river basins. At the heart of this process lie nine basin roundtables, grassroots committees whose mission centers on completion of comprehensive basin-wide water needs assessments, including an evaluation of both consumptive and non-consumptive needs.

Consumptive uses include municipal, industrial and agricultural water diverted and consumed from rivers or tapped from the ground. Non-consumptive needs are environmental and recreational uses that benefit when water stays in the stream.

The roundtables will also assess the availability of water supplies in their basins and propose projects or other methods for meeting water supply needs.

Precursor to the Interbasin Compact Process: SWSI

Driving the roundtables' work are the findings of the Statewide Water Supply Initiative, commonly known as SWSI, a detailed assessment of the state's water outlook initiated in 2003. Rick Brown of the consulting firm Camp, Dresser and McKee, or CDM, says the Colorado Water Conservation Board, which he worked for at the time, developed SWSI after observing three trends early in the decade: Colorado's booming population, increasing demands for non-consumptive uses like recreation and environmental protection, and the 2002 drought.

Brown says, "We started thinking, 'How well are we prepared for our future in terms of water supply?' We really didn't have a comprehensive picture of where the state was and where it was going to be in 30 years." The goal of SWSI was to provide that picture.

The first phase of SWSI resulted in a November 2004 report from the CWCB and Department of Natural Resources that predicted Colorado will need an additional 630,000 acre feet of water by 2030 as its population swells from 4.3 million in 2000 to an estimated 7.1 million. SWSI I also calculated the gap between supply and demand for each basin, concluding the state was 118,000 acre feet short of meeting future demand with the identified projects and processes, or IPPs, that could supply more water.

One concern Brown acknowledges is that SWSI made optimistic assumptions about water supplies, in part because some of the IPPs in the report overlap with another entity's identified project or will simply never come to fruition. "The gap is likely to be larger," he says. Just how much larger is still unknown.

To address this concern, the CWCB is developing a database to track projects into the future; as the agency monitors whether projects come on-line, are amended, or prove unsuccessful, it will know where assistance is needed and be able to recalculate the water supply gap.

Eric Hecox, section chief of Intrastate Water Management and Development for the CWCB, says the state recognizes that not all the IPPs will pan out, but even if they did there will be a 20 percent water supply gap. ‘If they are successful, we have a problem. If they're not successful, the problem is bigger,’ says Hecox.


Refining and filling in the data gaps

Though the roundtables are using SWSI's numbers -- provided through basin-specific reports -- as a baseline for their needs assessments, they are updating, refining and adding to the information as necessary. One way they are doing this is by incorporating other, existing and ‘appropriate sources of information’ such as water quantity studies, flow agreements and biological opinions.

The roundtables are also eliciting new data. The IBCC has encouraged the roundtables to use a ‘common technical platform’ for the assessments; by using common methodologies and similar assumptions, the resulting data will be consistent and comparable. To assist the roundtables in maintaining that consistency, the state has contracted with a team of firms led by CDM to complete the technical work, which includes both studies the roundtables are directing as well as statewide evaluations for the IBCC and CWCB for which the roundtables have input.

The non-consumptive needs assessments have been particularly challenging due to the extent of the data gap. Through these assessments, the roundtables are identifying the highest priority areas in their basins for protecting environmental and recreational values and attempting to quantify the levels of seasonal flows necessary to maintain those values. These site-specific quantification studies are especially time- and resource-intensive, which is one reason why the roundtables are establishing priority areas.

These needs were not initially taken into account by SWSI I, a concern to some from the environmental community, who were dubious from the outset of the initiative. From Dan Luecke's perspective, the very structure of SWSI signaled that it put non-consumptive uses in a second-class position. Luecke, a consultant for Trout Unlimited and Western Resource Advocates who sat temporarily on the South Platte Basin's SWSI roundtable, says, ‘It was always an implicit assumption that meeting agricultural or municipal demands was more important. It was nice if something was left for instream flows.’ He also believes consumptive uses were overestimated in every basin. ‘If you were going to honor these demands, there wasn't going to be anything left for instream flows.’

SWSI's second phase worked harder to identify environmental and recreational uses. And the Interbasin Compact Process is attempting to further elevate non-consumptive uses from the second-class tier they've historically been relegated by evaluating needs for instream flows side-by-side with consumptive uses.

Not everyone agrees SWSI overestimated consumptive needs either. In fact, the method used, which was based on the State Demography Office's population projections, was specifically chosen to be conservative, says Hecox. The roundtables have commissioned various studies that will add a level of detail and address specific, localized demands they felt weren't adequately covered by SWSI's broader, lay-of-the-land approach.

Basin roundtables' studies

The Energy Development Water Needs Assessment is a joint effort of the Colorado and Yampa/White/Green basin roundtables to assess water demand for energy needs in their basins. The first phase of the energy study, released in September 2008, found that the amount of water required for natural gas, coal, and uranium production could be met with available water supplies, but oil shale development, along with associated power production and population growth, could require up to 378,300 acre feet annually.

The study developed a matrix of high-, medium- and low-production scenarios, as well as short-, mid-, and long-range timeframes. Though the near 400,000 acre-foot figure is receiving much attention, the study actually produced a range of numbers. Representatives from the joint energy subcommittee of the Colorado and Yampa roundtables say they are using a mid-range number for planning purposes, something closer to 100,000 acre feet.

The second phase of the study, which will examine where water to meet energy demands could come from, is just getting started. Critical to that work will be the results of the Colorado River Water Availability Study. Greg Trainor, utility and street systems director for the city of Grand Junction, says a full-scale oil shale industry could use up the balance of water available under the 1922 Colorado River Compact.

Some representatives of the oil industry think the energy study drew its conclusions based on exaggerated figures for water use associated with oil shale development. Tracy Boyd, communications and sustainability manager for Shell Oil, says the study's high-end estimate of 378,300 acre feet per year assumes production of 1.5 million barrels of oil per day. Based on the three-to-one ratio Shell uses for estimating water use per barrel of oil, producing that much oil would require 212,000 acre feet per year. Shell thinks it can do even better than that.

In addition, the study was based on assumptions that the large amount of energy associated with extracting oil shale would come from traditional coal-fired power plants, which Boyd says is the second-most water intensive form of energy production after nuclear. He says it's unlikely that 30 years from now, given global warming issues and the anticipated regulatory climate for carbon dioxide emissions, the industry would rely on that form of energy. Still, the study's conclusions have raised many an eyebrow and given the affected basins, and everyone else, reason for concern.

Another roundtable waiting on a commissioned study to complete its consumptive needs assessment is the Gunnison Basin, which felt is agricultural needs were underestimated by SWSI. In addition, the Gunnison Basin Roundtable is looking at water demand for snowmaking in the Upper Gunnison.

Because of their shared hydrology, the Metro and South Platte Basin roundtables are developing a joint water needs assessment that is expected to further refine anticipated needs on the Republican River in the Eastern Plains and headwaters areas. The analysis, completed in draft form, also examines where multiple providers are eyeing the same water for a future supply, what the impact of water administration changes on the availability of water will be, and how increasingly efficient water reuse will affect downstream users.

Other basin roundtables are refining their assessments based on needs unique to their basins. For example, the North Platte Basin Roundtable assessed water supplies for the town of Walden and is implementing the resulting recommendations; the Rio Grande Basin Roundtable has initiated a well monitoring program south of the Rio Grande River; and the Arkansas Basin Roundtable is looking at alternatives to agricultural dry-up.

Statewide efforts

The roundtables' efforts are being supplemented by other studies, including the state's work with CDM to extend SWSI's 2030 projections out to 2050 and recalculate the gap for each basin. This study will also consider the role of climate variability and groundwater sustainability, two factors that could lead to declining water supplies.

Though the study remains in draft form, initial 2050 projections estimate a statewide population of 8.5 to 11 million and an associated increase in municipal and industrial demand of 1.7 million acre feet. That figure takes into account high-end population growth and the maximum figure for oil shale development.

Another CWCB study, which is evaluating the possibility of maximizing Colorado's use of Colorado River Basin water, is the Colorado River Water Availability Study. The availability study's first phase is expected to be completed by September and will determine the amount of water remaining from Colorado's allocation under the Colorado River Compact. Estimates for how much water is unallocated and available for development in the Colorado River system are currently all over the board, says Hecox. According to the 1922 compact and the subsequent Upper Colorado River Basin Compact of 1948, Colorado is entitled to just over half of the 7.5 million acre feet it must share with Wyoming, Utah and New Mexico, which would be 3.8 million acre feet. Colorado currently uses up to 2.8 million acre feet, which means 1 million acre feet remain. However, it is widely accepted that the data used to set the numbers for the agreements came from wetter-than-average years. The most recent U.S. Bureau of Reclamation Hydrologic Determination stated the river's flow is averaging at level low enough that it would be impossible for all the compact's parties to get what they planned on. If Colorado indeed gets a smaller share, and the state's currently planned projects are taken into account, the amount of water remaining may be as low as 150,000 acre feet, according to Eric Kuhn, general manager of the Colorado River Water Conservation District.

‘The study's not going to come up with a specific number, but rather a range of how much water is left that can be safely developed under the compact entitlement,’ says Eric Wilkinson, general manager of the Northern Colorado Water Conservancy District and CWCB board member. ‘That's going to have to be coupled with a risk analysis looking at if we develop it, what's the risk of a compact call and what can be done to reduce that risk?’

The availability piece of the needs assessments has been completed for all but the West Slope basins; each has concluded there is no new water available. Jeris Danielson, general manager for the Purgatoire River Water Conservancy District, says the Colorado River's availability study will have implications statewide. ‘The only unused water we have is in the Colorado River Basin, so until we know how much is unused, it's very difficult to come up with ways to meet those needs.’ He says transfers from irrigated agriculture are currently meeting the majority of municipal needs, and while everyone recognizes that ag transfers will be required to meet some portion of future demand, they question how many acres will be sacrificed. If all the 2050 demands were met through ag transfers, the state would realize a 70 percent reduction in irrigated acres on the East Slope and a 65 percent reduction on the West Slope.

As the state proceeds with a study evaluating additional strategies, both to reduce demands through conservation and reuse and to develop supplies through various means, some are already anticipating the hard questions. The balance between supply and demand, evidenced by the numbers coming out of the various studies, still isn't adding up.

Says Trainor, ‘There isn't enough water around here, folks, and there's going to have to be a serious examination of the state's priorities and what kind of uses we want water going toward.’

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