Conservation Guidelines for Assessing the Potential Impacts of Wastewater Discharges to Wetlands

A. Wetlands-a definition 1 B. The need for this document 1 1. Increased interest in the use of wetlands for disposal of wastewaters 2 2. Prediction of future pressures on wetlands 2 3. Review of resource statutes 3 4. Promotion of constructed wetlands 3 5. Conflict with conservation? 4 C. Who should read this report and how is it structured? 5 II. ECOLOGICAL IMPACTS OF WASTEWATER DISCHARGES TO WETLANDS-A REVIEW A. Functions and uses of wetlands 6 1. Geomorphology 6 2. Hydrology 6 3. Water Quality 8 4. Ecology 8 5. Cultural resources 9 B. Changes to wetlnd functions arising from waste discharges 9 1. Hydrology 10 2. Water quality 11 a) Organics 11 b) Nutrients (nitrogen and phosphorus) 11 c) Heavy Metals 14 d) Pathogens 15 3. Ecology 15 a) Flora 15 b) Fauna 17 c) Conclusions 17 C. Potential impact of wastewater discharges on wetland functions-summary 18 III. GUIDELINES FOR ASSESSING POTENTIAL WASTE DISCHARGES TO WETLANDS A. Introduction 22 B. Preliminary screening 22 1. Wastewater management objectives and characteristics 23 2. Wetland Type 24 3. Environmental condition and sensitivity 25 4. Wetlands values and uses 26 C. Detailed evaluation 27 1. Hydrology 28 a) Hydrologic pathways 28 b) Water budget and hydroperiod 28 2. Water quality 30 3. Ecology 32 4. Soil characteristics 33 5. Predicting assimilative capacity 34 D. Suggested audit trail for wastewater/wetland proposals 35 IV. REFERENCES 38 V. APPENDICES-RESOURCE MATERIAL 43 A. Wastewater composition 43 B. Glossary of technical terms 45 C. Some suggested specialist contacts. SUMMARY This report is intended for Conservation Officers responsible for the assessment of the potential impacts of a wastewater discharge to a wetland. The report is divided into two main sections. Chapter II reviews the ecological impacts which wastewater discharges may have on wetlands. The material in Chapter II is intended to be suitable for either conservation officer or scientist who wish to obtain an overview of the subject. Some general guidelines are also given on the effects which a wastewater discharge may have on other wetland functions. Based on the review, Chapter III presents some practical guidelines for undertaking an assessment of a waste discharge proposal. This chapter is split into two main sections; the first being the 'preliminary screening' of a proposal. The level of evaluation relies largely on existing data and can be carried out by DOC staff. Based on the findings of the preliminary screening, …