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WWRC 84-12
Acidic Depositions in Wyoming

Executive Summary

Recent reports indicate that two-thirds of the United States and one-half of Canada receive acidic depositions. Commonly referred to as "acid rain", acidic depositions have been defined as precipitation that has a pH level less than 5.65, the theoretical natural acidity level of distilled water in equilibrium with atmospheric carbon dioxide. Acidic depositions can include rain, sleet, snow, fog, dew, dry particles, and gases. The major causes of acidity in acidic depositions are sulfates, nitrates, and possibly organic anions. Chemical analyses indicate that petroleum and coal burning, and ore smelting may all be important emission sources for these chemicals in the West.

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.

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 wee 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:

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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