Input to the models can be modified in order to estimate impacts associated with various water projects.
Available Ground Water
Groundwater resources of the Basin are largely undeveloped at this time. Consequently, sparse information is available to evaluate groundwater characteristics and development prospects in the Basin.
Ground water is principally used for drinking water supplies and industrial use. The majority of the supplies are developed from Quaternary and Tertiary aquifers. Current groundwater use within the Greater Green River Basin is estimated at 5,300 to 7,200 acre-feet per year
The majority of the study area is underlain by rocks that are host to several important aquifers, including the Frontier aquifer (western part of the Basin), the Mesaverde aquifer, and the Tertiary aquifer system.
Various estimates of groundwater recharge by precipitation derive a potential basin groundwater yield between 50,000 and 100,000 acre-feet per year. Thus, there is no evidence to suggest over-development of the principal aquifer systems. It may be concluded that there is significant potential for additional development of these aquifer systems, with little risk of depleting this resource.
There are many factors that may affect future development and availability of groundwater resources. In the case of alluvial aquifers, any future development of groundwater resources may be expected to have a direct and near-immediate impact on the adjacent rivers and streams within the alluvial system. The quality of water extracted as a by-product of potential coal bed methane (CBM) development in the Basin is reported to be significantly worse than in the Powder River Basin. Limitations imposed by Interstate Compact on the quality of water discharged to the Green River may require that the co-produced water be treated or reinjected. The impacts of the added costs of treatment or reinjection are unclear, but may render some CBM projects uneconomical. At this time, it appears unlikely that the level of development of CBM resources in the Greater Green River Basin will match the levels of development anticipated in the Powder River Basin given current market and environmental conditions.
Demand Projections Summary
For assessing the need for water into the future, this plan has developed estimates of water demand for each major use category out to year 2030. A summary of all projected uses is provided in the following table. Values are acre-feet per year:
Agricultural Use Projections
Future demands for additional irrigation water in the Green River Basin are largely dependent upon factors that might either increase the returns that Basin irrigators receive from irrigation or reduce the cost to them of developing new storage. Possibilities for increasing economic returns to irrigated agriculture in the Basin include diversifying cropping patterns into higher valued crops, the possibility that hay prices may rise to the point that it would be profitable to export hay from the Basin to other domestic markets, the possibility that cattle prices may rise significantly over the next 30 years, and an increase in the amount of financial assistance available to producers for reservoir construction from State and federal agencies.
The types of hay expected to be in high demand in the future are alfalfa for dairies and Timothy hay for horses. If future market prices for these crops stabilize at levels of well over $100 per ton, it may become practical for Green River Basin producers to develop additional storage and expand production of these crops for export markets.
Municipal/Domestic Use Projections
Three methods of producing population forecasts were evaluated. The Division of Economic Analysis of the Wyoming Department of Administration and Information produces population forecasts based upon time series data from which growth rates are derived from variables such as population, sales tax collections, and school enrollments. Second, the United States Census Bureau periodically produces population forecasts using mortality rates, fertility rates, and migration patterns. A third set of population projections assumes that the area would experience a total population increase during the period from 2000 to 2030 that is of the same magnitude that occurred during the 30-year period from 1960 to 1990.
Projections were made using high, moderate, and low growth scenarios. Current municipal and domestic water consumption rates were applied to population projections to estimate a potential increase of future municipal and domestic use of 40 to 60 percent.
Industrial Use Projections
The largest industrial water uses in the Basin involve electric power generation and soda ash production. Future water needs for electric power production in the Basin will be largely determined by how electric utilities in the Basin and elsewhere in the west respond to growing demands and various actions and proposals to deregulate the industry. Scenarios for possible industry responses to deregulation are not easily developed. Similarly, future growth prospects for the soda ash industry are largely dictated by the ability of Wyoming producers to capture an increasing share of the international market in the face of volatile international economic conditions and the protective tariffs imposed by some foreign countries.
Under a low growth scenario, surface water requirements for large industrial water users may increase by as little as 17 percent. A moderate growth scenario projects a reasonably foreseeable increase of 68 percent, while a high growth scenario projects an increase of 150 percent.
Recreation Use Projections
According to the Wyoming Game and Fish Department, the Green River could provide an annual supply of nearly 1,122,800 activity days of lake and reservoir fishing opportunities. When contrasted with the current rate of about 485,000 activity days of use annually, there is presently no apparent shortage of still water angling opportunities in the Basin.
A different conclusion applies to the Basin's stream fisheries. In 1988, the Wyoming Game and Fish Department estimated a total supply of about 411,000 angler days of stream fishing opportunities available in the Basin, but only about 213,000 angler days of this supply were in areas where public access was guaranteed. That figure contrasts with a current estimated annual use of about 300,000 angler days of activity, and projected demands in the range of 327,000 to 566,000 angler days of activity by the year 2030. These estimates indicate that the Basin's stream fisheries are already at capacity, and will come under increasing pressure in the future as its population increases and tourism related fishing pressure grows.
Environmental Use Projections
Environmental water requirements are not necessarily related to changes in population or tourism in the Basin. Instead, environmental water requirements are at least partially a function of human desires concerning the type of environment in which people want to live. These desires are expressed through environmental programs and regulations promulgated by elected representatives at the state and federal levels. Thus, future environmental water requirements in the Green River Basin will be determined, at least partially, by existing and new legislation dealing with environmental issues at the state and federal levels, and how that legislation is implemented by federal and state agencies.
Wyoming's instream flow statutes recognize such non-consumptive flows not only contribute to aesthetic character and biological diversity of the Basin, they also support recreational fisheries that are important to Basin residents and to the Basin's economy. Five reservoirs in the Basin have "fish" or "fish and wildlife" uses listed in their permitting documents: Big Sandy, Boulder, Flaming Gorge, Fontenelle, and High Savery. Given the current federal regulatory environment and the desires of the public to maintain and enhance recreational fisheries in the Basin, it is likely that any additional storage developed in the future will have a provision of minimum reservoir pools for fish and wildlife purposes.
Water Development Needs and Opportunities
Considering consumptive uses of water, only the agriculture sector experiences current shortages. Predictably, these shortages are in areas not already served by storage to any significant extent. Unfortunately, the main reason these shortages exist is that agriculture is the economic sector least able to afford the high cost of storage construction. This is especially true for those operators focused upon raising forage instead of cash crops, to provide late season supplemental supplies.
Therefore, the general direction taken for recommending future use opportunities focused largely on providing supplemental irrigation supplies. Multiple use opportunities were also considered because the effects of the various projects on environmental and recreational values (including funding) are very important and can result in otherwise similar projects being viewed quite differently.
Nine previously completed planning studies, new project ideas suggested by Basin Advisory Group (BAG) members, and an initial screening of clearly unfeasible or unlikely candidates provided over 45 projects to review for potential application to current and future needs. Groundwater development and conservation opportunities, such as conversion to sprinkler irrigation or canal rehabilitation, were also evaluated on a regional (sub-basin) basis.
Based upon comments received during BAG meetings, review of previously published criteria and questionnaire results, and the Scope of Services, a procedure for screening opportunities for future water use was developed. The procedure included a prioritization based on need, and evaluative criteria based on favorability. Projects were initially prioritized according to the following schedule:
Six criteria under each of these priorities aim to present an overall picture of the favorability of a project. These include factors ranking water availability, financial feasibility, public acceptance, number of sponsors/beneficiaries/participants, legal/institutional constraints, and environmental/recreational benefits.
The Green River Basin Plan provides detailed strategies for coping with institutional and financial constraints on water project development.
Future Water Plan Directives
This document is intended to be used as a reference for citizens of the State of Wyoming and agency personnel to understand the current state of water use and development in Wyoming's Greater Green River Basin. It will be available to legislators as background material when evaluating future water development funding decisions. It can be referred to for assistance in establishing purpose and need for future water development project work. Agency personnel will, upon critical review and with experience from its use, find areas to be more closely evaluated in subsequent updates.
The Wyoming Water Development Commission, the state revolving fund for water treatment facilities, federal assistance through the USDA Rural Development Program and various conservation programs (e.g. the Conservation Reserve Program and Wildlife Habitat Incentives Program) all provide water development assistance for municipalities, irrigation districts, and individuals to perform necessary and valuable work that they otherwise could not afford. Because water development in the form of water treatment improvements and environmental enhancements are desirable goals, these programs are vital to the overall quality of life in the Basin.
Water development has become difficult and costly. However, if a project proponent has a need for water, patience, and financial resources, the federal permitting process can be successfully completed. Wyoming must maintain its resolve to develop its water resources to meet the needs of its citizens.
The publication of the Green River Basin Planshould foster discussion among water users and state officials relative to water development in the Green River Basin in Wyoming. The plan concludes that Wyoming has water to develop in the Basin. The water can be used for future municipal and industrial growth. There are existing agricultural water demands that could be met with the water.
As long as Wyoming has water to develop in the Green River Basin, there will be debate regarding the sale or lease of water to downstream interests. Storage water or other supplies that can be delivered on demand may offer revenue potential for the State.
The Green River Basin Plan is an important step towards identifying and achieving Wyoming goals in the Green River Basin. It is important to update and maintain the Green River Basin Plan or it will simply be a glimpse of the status of the water use at the end of the twentieth century. In order to improve on the plan, additional data will be necessary, and the understanding of existing water use must be maintained or improved.