Water Quality of Wizard Lake
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WATER QUALITY OF WIZARD LAKE Prepared by: Patricia Mitchell, M.Sc., P. Biol. Water Sciences Branch Water Management Division Natural Resources Service September, 1998 W9810 ENVIRONMENTAL PROTECTION Pub. No: T/824 ISBN: 0-7785-4262-9 (Printed Edition) ISBN: 0-7785-4263-7 (On-Line Edition) Web Site: http://www3.gov.ab.ca/env/info/infocentre/publist.cfm Any comments, questions, or suggestions regarding the content of this document may be directed to: Environmental Monitoring and Evaluation Branch Alberta Environment 10th Floor, Oxbridge Place 9820 – 106th Street Edmonton, Alberta T5K 2J6 Phone: (780) 427-6278 Fax: (780) 422-6712 Additional copies of this document may be obtained by contacting: Information Centre Alberta Environment Main Floor, Oxbridge Place 9820 – 106th Street Edmonton, Alberta T5K 2J6 Phone: (780) 427-2700 Fax: (780) 422-4086 Email: [email protected] i EXECUTIVE SUMMARY Increasing development pressure at Wizard Lake prompted the counties of Leduc and Wetaskiwin to review the lake management plan that was adopted in 1980. One of the main issues relevant to further development is water quality of the lake. The planning committee members asked Alberta Environmental Protection to provide updated information on the lake’s water quality, particularly whether it had changed over the years. This report summarizes available data and updates a phosphorus budget that had been prepared for the lake several years ago. Wizard Lake was sampled in 1978-79, 1981-82, 1984, 1988 and 1996. A variety of methods and sampling frequencies were used, but the data are sufficient to determine whether lake water quality has changed over this 20-year period. The phosphorus supply to the lake from various sources was recalculated based on new information, although the phosphorus input was not actually measured. Wizard Lake is very highly productive, or hyper-eutrophic, according to the amount of algae in the lake in 1996. This means it will have blue-green algal blooms, murky water and heavy growth of aquatic vegetation. The condition of the lake has not changed over the period of record, although the “green-ness” of the water varies over the summer and from year to year. Phosphorus is a key nutrient for lake water quality, because when the phosphorus supply to a lake increases, recreational water quality deteriorates. The updated phosphorus loading estimates suggest that the phosphorus supply is lower than that calculated in the early 1980s. This difference largely results from different assumptions and calculation methods used for the updated version. The estimated total phosphorus supply to the lake seems to be in line with the measured average level of phosphorus in the lake, and with measured phosphorus budgets on other central Alberta lakes. To protect or improve water quality in Wizard Lake, nutrient loading should be reduced. This can be accomplished in a variety of ways, including careful planning of new development, education of stakeholders, runoff controls in the watershed and correction of malfunctioning septic systems. ii ACKNOWLEDGEMENTS Numerous people have been involved in collecting water quality data on Wizard Lake over the years, including graduate students of Dr. Ellie Prepas (University of Alberta), staff of the former Pollution Control Division of Alberta Environment and members and volunteers of the Alberta Lake Management Society (ALMS). Monitoring Branch of Alberta Environmental Protection (coordinated by John Willis) assisted ALMS and the volunteers, and analyzed phosphorus and chlorophyll a samples. Chacko Abraham provided hydrological information. David Ramsay of Alberta Labour provided new cottage use information, and the West Central Planning Agency provided additional information on watershed characteristics. Bridgette Halbig formatted the report and prepared the water quality graphs. David Trew and Doug Yeremy reviewed the manuscript. iii TABLE OF CONTENTS EXECUTIVE SUMMARY..........................................................................................................................i ACKNOWLEDGEMENTS .......................................................................................................................ii LIST OF TABLES......................................................................................................................................iv LIST OF FIGURES ....................................................................................................................................v 1.0 INTRODUCTION .........................................................................................................................1 2.0 METHODS .....................................................................................................................................1 3.0 RESULTS........................................................................................................................................3 3.1 HYDROLOGY...................................................................................................................3 3.2 PHYSICAL AND CHEMICAL CHARACTERISTICS ....................................................6 3.2.1 Major Ions..............................................................................................................6 3.2.2 Temperature and Dissolved Oxygen......................................................................8 3.2.3 Nutrients and Trophic Status ...............................................................................10 3.3 NUTRIENT LOADING ...................................................................................................12 4.0 DISCUSSION AND CONCLUSIONS .......................................................................................15 5.0 LITERATURE CITED................................................................................................................17 iv LIST OF TABLES Table 1. Characteristics of Wizard Lake. .................................................................................................. 3 Table 2. Average concentrations of major ions and related variables for Wizard Lake, May-September 1978-79, 1988 and 1996. .................................................................................. 6 Table 3. Average concentrations of nutrients and related variables in Wizard Lake 1978-79 and 1996........................................................................................................................ 10 Table 4. Theoretical total phosphorus loading to Wizard Lake................................................................. 14 v LIST OF FIGURES Figure 1. Features of the drainage basin of Wizard Lake ........................................................................... 4 Figure 2. Bathymetry and shoreline features of the main basin of Wizard Lake........................................ 5 Figure 3. Monthly mean water levels for Wizard Lake near Leduc (station 05DF901)............................. 7 Figure 4. Vertical profiles of temperature and dissolved oxygen in Wizard Lake, sites 1 & 3, winter and summer, 1978-1979................................................................................ 9 Figure 5. Open-water Secchi depth and concentration of chlorophyll a and total phosphorus in Wizard Lake, east and west, 1996 ............................................................... 11 Figure 6. Average open-water Secchi depth and concentrations of chlorophyll a and total phosphorus in Wizard Lake.......................................................................................... 13 1 1.0 INTRODUCTION Wizard Lake is a popular recreational lake that lies south of Calmar, Alberta and northeast of Pigeon Lake. Even in the 1970s, recreational use of the lake was so intensive that in 1977 it was named as one of 15 lakes in the province to be designated under the Regulated Lake Shoreland Development Operation Regulations. The regulations prohibited most development until a lake management plan was drawn up. The management plan was developed by the former Battle River and Edmonton Regional Planning Commissions for the counties of Wetaskiwin and Leduc. The management plan focussed mainly on land use for various activities, using an integrated use approach. Water quality protection was not a major factor in the development of the plan. With increasing pressure for development on this lake, the counties decided to update the management plan. For this update, water quality was to be a major element because it was recognized that without water quality protection, the lake experience sought by cottagers would decline. Of particular concern was whether lake water quality had changed since the previous management study was done. As well, there was interest is identifying sources of nutrients that cause water quality deterioration. This report presents a brief summary of existing knowledge about water quality in Wizard Lake. Because nutrient inventory work in the watershed has not been done, the phosphorus budget presented is based on information derived from other studies on Alberta lakes and extrapolated to Wizard. No attempt was made to determine a lake development carrying capacity based on water quality, because we believe that properly designed and situated cottage subdivisions, with careful controls on septic systems, should not contribute to water quality deterioration. 2.0 METHODS Alberta Environmental Protection (AEP), the University of Alberta and the Alberta Lake Management Society have sampled Wizard Lake over the