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WWRC 84-12
Acidic Depositions in Wyoming

Executive Summary

While not currently perceived as a problem in Wyoming, acidic depositions have been found in this State and others in the Rocky Mountain Region. And, industrial developments are planned in the region (e.g., gas sweetening plants near the Overthrust Belt of southwestern Wyoming) that will have atmospheric emissions of potentially acid forming chemicals. Consequently, concerns about potential adverse impacts from acidic depositions in Wyoming are increasing. The following report is a result of requests from the Wyoming Game and Fish Department and the Wyoming Environmental Quality Council to the Wyoming Water Research Center for information and advice useful in addressing these concerns.

Acidic depositions have been suggested to produce adverse effects upon a number of resources. In this document are reviewed the current state of the scientific knowledge for the known effects of acidic depositions on soils, Crops, forests, surface-water quality, aquatic organisms, human health, and cultural materials. Overall, the most significant effects have been suggested to occur in poorly buffered surface-waters.

Although no actual effects have been observed in the State, a number of general conclusions can be made about the possible effects by acidic depositions on the resources of Wyoming.

• Soils - Within the non-mountainous regions of Wyoming, natural conditions have created alkaline soils generally considered as insensitive to acidic depositions. Potentially sensitive soils would be limited to thin, poorly buffered soils present on slowly-weathered bedrock, such as granite. These areas are generally confined to higher elevations in some mountain ranges.
• Crops - Since virtually all crops in Wyoming are grown in relatively arid areas thar have insensitive alkaline soils, acidic depositions should have no adverse effects. Such depositions, in fact, may produce fertilizing effects.
• Forests - Forest tree spedes which have been suggested to be potentially sensitive to acidic depositions in the northeastern United States also grow in Wyoming. These species include spruce, firs, and pines. There are no data, however, demonstrating whether Wyoming forests are potentially sensitive to acidic depositions.
• Surface-water quality - While few data are generally available, enough exist to indicate that some high mountain areas contain a relatively high proportion of lakes potentially sensitive to acidic depositions. Such lakes have alkalinity levels less than 200 µeq/l. For example, one data set indicates that about 70 percent of the lakes over 9,000 feet elevation in the Wind River Range may be potentially sensitive to acid inputs. Because of natural characteristics, lakes and streams at lower elevations and in non-mountainous regions are generally well buffered and are, therefore, considered insensitive to any probable future inputs of acidic depositions. It should be emphasized, however, that present acidic deposition rates in Wyoming do not appear to pose a threat to Wyoming surface waters.
• Aquatic organisms - Wyoming lakes and streams that are potentially sensitive to acidification by acidic depositions contain many aquatic species potentially sensitive to acidity. If these waters were to become acidic (pH levels below 6.0), many of these species would be adversely affected. Depending on the degree of acidification, some species populations could become locally extinct. However, acidic deposition rates would have to be many times greater than currently reported for the State before these affects would be likely to occur.
• Human health - While potential adverse effects to human health from acidic depositions have been hypothesized, actual effects have not been documented for any human population. Therefore, although the potential may exist for acidic depositions to cause health effects in Wyoming, the possibility of such effects developing is unknown and probably very small.
• Cultural materials - Cultural materials exist in Wyoming that are potentially sensitive to acidic depositions, but these materials are primarily located in the more populated, non-mountainous, relatively arid regions of the State. Therefore, potentially adverse effects from future acidic depositions in Wyoming will likely have little detectable effects on most cultural materials of concern.

In this review a number of research needs were identified as valuable in helping to understand the possible significance of acidic depositions in Wyoming. Lists of environmental monitoring and research projects were then presented that could help supply needed information. From these, various projects we·e recommended for a Wyoming sponsored monitoring and research program to investigate acidic depositions. Considerations involved in selection of the projects included probability of impacts, information gaps, data applicability, feasibility of completion, and costs.

The suggested monitoring and research program addresses five general areas viewed as important to an overall State sponsored program:

1. It must be determined whether acidity levels in atmospheric depositions are great enough to potentially cause future adverse impacts.
2. Sources emitting potentially acid forming chemicals, both in-state and out-of-state, must be identified and quantified to help in determining where controls may be needed and where downwind resources may be impacted.
3. Potentially sensitive natural and cultural resources must be identified to determine the location and the extent of resources potentially at risk from acidic depositions.
4. To definitively determine whether acidic depositions adversely impact any resource requires establishment of a monitoring and research program to determine possible trends of change for these resources and actual cause(s) of these changes.
5. As a result of efforts under the above four categories, additional actions will be defined that can help to evaluate potential effects of and mitigations and management measures for acidic depositions in Wyoming.

In relation to these five areas, nine monitoring and research projects are suggested:

• Compile and evaluate existing atmospheric deposition data.
• Monitor present atmospheric depositions.
• Inventory emission sources.
• Develop instate/out-of-state source budgets for acids in Wyoming airshed.
• Develop inventories of resources at potential risk, based on existing information.
• Select study sites for long-term collection of monitoring and baseline environmental data.
• Monitor for long-term changes in surface water quality and fish populations.
• Monitor for short-term changes in surface water quality following snowmelts and major rainfalls.
• Conduct soil surveys in watersheds surrounding the long-term study sites.

Of these, many can readily be completed using existing data, and several can be rapidly undertaken with Federal funding.

Due to the widespread concern about possible impacts from acidic depositions, many groups and individuals have potential interests and involvements in a State sponsored monitoring and research program. These potentially include 21 organizations in the Executive Branch of State government, 10 Standing Committees in the State Legislative Branch, over 25 Federal organizations, and a variety of industrial groups, environmental and conservation organizations, plus other miscellaneous groups. The possible interests and involvements of these organizations and individuals are briefly discussed.

It is concluded that. acidic depositions pose an unique environmental problem. Assessing the significance of the potential impacts to Wyoming will require an extensive state-wide monitoring and research program, coordinated by a single authority. Only through the cooperation among many State and Federal agencies, and a selection of other interested groups and individuals, can the present or future impacts from acidic depositions in Wyoming be accurately assessed.

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