WATER QUALITY OF WIZARD

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 Environment 10th Floor, Oxbridge Place 9820 – 106th Street , 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 prompted the counties of Leduc and 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 .

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.

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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

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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

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1.0 INTRODUCTION Wizard Lake is a popular recreational lake that lies south of Calmar, Alberta and northeast of . 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 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 years. Consequently, sampling methods have not always been consistent. For example, when the first lake study was conducted on Wizard (1978-79), samples were collected at the lake surface, mid-depth and near bottom in three areas of the lake. For the University of Alberta studies (1981-82 and 1984), samples were collected at various depths at several stations. In 1988, two sets of samples (June and September) were collected by AEP as whole-lake composite samples, and in 1996, volunteers sampled east and west ends of the lake as whole-basin composite samples for the Alberta Lake Management Society. Although these differences reduce the validity of direct year to year comparisons, the data base is sufficient to determine whether or not water quality in Wizard Lake has changed significantly over this 20-year period. Since about 1980, AEP has conducted most lake sampling programs by collecting whole- basin composite samples from the upper portion of the lake water column. To collect a sample, a clear 2 plastic hose is lowered from the lake surface through the zone that light penetrated on that day (measured with a submersible light meter or a Secchi disk). These hose samples are collected from several locations throughout the deeper areas of the lake and put into one container, called a composite sample. This provides an assessment of water quality in the lake as a whole, rather than in one particular area or along shorelines. Shoreline water quality varies from day to day, and therefore cannot be used to determine whether water quality in the lake is changing. For Wizard Lake in 1996, volunteers collected one composite sample from the east end of the lake and another from the west end. Other measurements were made during these studies as well, such as general water chemistry, temperature, dissolved oxygen, conductivity, pH and light. All of the sampling programs on Wizard Lake were designed to assess its trophic status, or level of fertility. Highly fertile lakes are ones with high nutrient concentrations, green scummy water and poor water clarity. Nutrient levels, the amount of algae and water clarity serve as indicators of fertility, and were therefore measured during all the lake studies. Essential plant nutrients (phosphorus and nitrogen) are measured directly in a water sample in the laboratory. Transparency is measured in the field with a black and white steel plate called a Secchi disk. The disk is lowered over the side of a boat and the depth that it disappears from view is noted. Often, suspended algae reduce the clarity of the water, so Secchi depth readings are inversely related to the amount of algae on the sampling day. The amount of suspended algae in the water is measured by extracting chlorophyll a from the sample; it is easily measured with a fluorometer, and provides a good estimate of the amount of algae in the sample on that day. To standardize the various data sets, only data that represented the zone of light penetration were used. Thus, data from samples collected near the bottom of the lake were excluded. Data from all stations were combined to give a whole-lake summer average for each year sampled. Aquatic vegetation surveys are not routinely conducted in AEP sampling programs, but one was conducted on Wizard Lake in 1979. The survey provides information on species of aquatic plants growing along the shoreline and submersed in the water. These surveys are done on macrophytes (the large plants people call “weeds”), not on suspended or filamentous algae. The survey indicates the abundance or density of shoreline plant communities, but they would not be quantitative enough to assess changes over time unless major changes in the vegetation had occurred. The results of the survey are included in the chapter on Wizard Lake in the Atlas of Alberta Lakes. The phosphorus loading estimate in the Atlas was updated for this report, based on the latest information available. Alberta Department of Labour (Plumbing Inspection Branch) and the Crossroads Regional Health Authority conducted a shoreline survey during the summer of 1998. The questionnaire included cottage use, type of septic systems and disposal, type of water craft used, drinking water source 3 and fertilizer and pesticide use. From this information, the use of the lake and the amount of phosphorus potentially contributed by septic systems could be calculated. The contribution of phosphorus from other sources was also recalculated where new information was available (see details in Results section below).

3.0 RESULTS 3.1 HYDROLOGY Wizard Lake is situated in a glacial meltwater channel that was originally formed in bedrock before the last glaciation. The watershed is partly forested and partly in agriculture. At the western end of the watershed, water flows into a shallow, pond-like basin connected to the main lake by a narrow channel (Figure 1). There are no permanent inflow streams, but during spring runoff and summer rains, several small creeks provide water to the lake. Water also flows into the lake from areas not drained by creek channels (diffuse runoff). The lake is also likely to be fed by groundwater, but the amount is unknown. Usually, the amount of groundwater contributing to central Alberta lakes is small compared with other water sources, and therefore is ignored in water balance estimates. The outflow, Conjuring Creek, flows to the . Table 1 gives general hydrological and morphological characteristics of Wizard Lake, and Figure 2 is a hydrographic survey map of the main part of the lake. The meteorological data listed in Table 1 are slightly different than those reported in the Atlas of Alberta Lakes, largely because a different reference creek was used to derive runoff data, but also perhaps because recent years have been somewhat drier.

Table 1. Characteristics of Wizard Lake. Sources: Atlas of Alberta Lakes; Abraham (1998). Elevation, m above sea level 784.01 Watershed Area, km2 29.8 Lake Area, km2 2.48 Volume, m3 14.8 million Maximum Depth, m 11 Average Depth, m 6.2 Long-term mean annual runoff inflow, m3 1.516 million Long-term mean annual precipitation, m3 1.210 million Long-term mean annual evaporation, m3 1.647 million Long-term mean annual outflow, m3 1.080 million Average hydraulic residence time, years 13.7

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The water level in Wizard Lake fluctuates over a range of about 1 m (Figure 3). The highest recorded water level occurred in 1990 (mean daily elevation 784.68 m), and the lowest in 1968 (mean daily elevation 783.586 m). The water level has been fairly stable since 1991-92, when a weir was constructed on the outlet with an elevation of 784.0 m. The hydraulic residence time for Wizard Lake is somewhat shorter than for many other lakes in central Alberta. For example, Pigeon, Gull and Wabamun lakes have hydraulic residence times that exceed 100 years, mainly because their watershed areas are small relative to their lake basins. The watershed area of Wizard Lake is about 12 times larger than the area of the lake, and therefore it fills and flushes more rapidly than these other lakes.

3.2 PHYSICAL AND CHEMICAL CHARACTERISTICS 3.2.1 Major Ions Table 2 shows average levels of major ions, alkalinity, hardness and other chemical attributes in Wizard Lake in 1978-79, 1988 and 1996. The water in Wizard Lake is low in dissolved solids (fresh, or low in salinity). The dominant ions are bicarbonate, sodium and calcium. Levels of several of the chemical characteristics listed in the table were higher in 1988 and 1996 compared with levels in the late

Table 2. Average concentrations of major ions and related variables for Wizard Lake, May- September 1978-79, 1988 and 1996. Units are mg/L unless indicated otherwise.

1978-79 1988 1996 pH (pH units – range) 7.4 – 8.9 8.3-8.4 7.95-8.44 Specific conductance, uS/cm 312 332 325 Total Dissolved Solids 172 187 187 Iron 0.07 Calcium 25 30.5 30.5 Magnesium 9 9 9.2 Total Hardness 97 113 114 Sodium 28 31 30 Potassium 4.6 4.8 5.8 Sulphate 6 6 3.9 Chloride 4 3.5 3.8 Silica 2.5 1.3 0.85 Total Alkalinity as CaCO3 155 169 163 Bicarbonate 182 201 199 Carbonate 3.5 <5 0.75 Number of samples 17 2 4 7

784.8

784.7

784.6

784.5

784.4

784.3 New Weir Elevation

784.2

784.1

784.0

783.9 LAKE ELEVATION (m) a.s.l. 783.8

783.7

783.6

783.5 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 YEAR Weir Installed

Figure 3. Monthly mean water levels for Wizard Lake near Leduc (station 05DF901)

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1970s. The cause is likely related to climatic variations, because concentrations have increased over this time period in many central Alberta lakes. There was a very heavy runoff during spring 1974, when many lakes in central Alberta received sufficient inflow to be flushed with very dilute water (there was also considerable property damage from flooding). Concentrations of major ions would likely have been much lower as a result of this dilution, requiring several years afterward to achieve a more “normal” level of these substances. The 1980s were fairly dry as well, which would contribute to concentration of dissolved substances in the lake water through evaporation. This increase in levels of major ions and other substances is not a cause for concern – they are well within the optimum range for species of animals and plants present in Wizard Lake.

3.2.2 Temperature and Dissolved Oxygen In winter and summer, temperature and dissolved oxygen were measured at 1 m intervals from the surface of the lake to the bottom. The winter temperature profile in Wizard Lake is typical of many lakes: the water is warmest at the bottom (Figure 4). For example, in March 1978, the surface temperature was less than 1oC while at the bottom it exceeded 3oC. Dissolved oxygen usually becomes depleted near the bottom of the lake under ice, and concentrations decline throughout the water column. In the winter of 1982-83, there was no oxygen in the water at the bottom, and even at the top the concentration was only 3 mg/L. In spite of these low concentrations of dissolved oxygen, winter fish kills almost never occur in Wizard Lake. There is some evidence that the lake does not mix completely in spring some years. In May of both 1978 and 1979, dissolved oxygen was less than 5 mg/L below a depth of 7 m. If the lake had mixed completely, dissolved oxygen concentrations would have been much higher at that time of the year. The sheltered aspect of the lake likely prevents wind action from mixing the lake thoroughly as occurs on most lakes in spring. All of the historical summer data suggest that Wizard Lake stratifies (forms a warmer layer of water over top of a cooler layer), but this occurs only temporarily in mid-summer. This is particularly evident in the graph at site 3 on August 1, 1979 (Figure 4). During stratification, dissolved oxygen is rapidly depleted in the bottom layer because oxygen from the air cannot replenish the supply used up through decomposition. Sometimes, a strong wind will mix the lake, but if very hot, calm weather occurs, the stratification may set up again. Even though the lake may mix on windy days, dissolved oxygen gradually depletes near the bottom as the summer progresses. Very rarely, summer fish kills may occur. This is usually caused by decomposition of a heavy algal bloom during warm, calm weather. Dissolved oxygen becomes rapidly depleted overnight and fish may die in certain areas of the lake, especially in shallow bays.

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3.2.3 Nutrients and Trophic Status The main nutrients of concern in Wizard Lake, as in most lakes, are phosphorus and nitrogen. Phosphorus is particularly important because it tends to govern the amount of plant life a lake can produce. If the supply of phosphorus to the lake increases, the amount of plant material (particularly algae, but perhaps also shoreline vegetation) in the lake also increases. This is less true of nitrogen, because the atmosphere is a source of nitrogen and it is usually in good supply. During lake water quality assessment studies, phosphorus is used as a major indicator of lake productivity, and much of the following discussion will focus on this indicator. Table 3 presents average data for phosphorus, nitrogen and other indicators of lake productivity. When there is an abundance of nutrients in a lake, it is said to be highly productive or fertile. The technical term for this condition is eutrophic. A eutrophic lake becomes quite green in summer, and submersed and emergent aquatic vegetation is abundant. Sometimes the nutrient supply is so great that nuisance blue-green algal blooms occur, leading to scummy water, noxious odours and potential for fish kills. This condition is called hyper-eutrophic, which simply means very highly productive. According to its average phosphorus levels, Wizard Lake is eutrophic. Its average chlorophyll a concentration in 1996, however, puts it into the hyper-eutrophic category. It has algal blooms and weed growth, but not to the extent that some lakes get.

Table 3. Average concentrations of nutrients and related variables in Wizard Lake 1978-79 and 1996. Units are µg/L unless indicated otherwise.

1978-79 1996 Total Phosphorus* 62 68 Total Nitrogen, mg/L 1.39 1.26 Ammonia-Nitrogen 0.09 0.02 Nitrite+Nitrate-N 0.029 0.003 Chorophyll a 27.2 30.4 Secchi depth, m 1.75 2.0 Number of samples 30 7 * 1978-79 Phosphorus data approximate.

Figure 5 shows how the nutrient phosphorus varied over the summer of 1996 in comparison with chlorophyll a levels and transparency of the water (Secchi depth). The east and west ends of the lake were sampled separately. Note that the patterns over the summer were fairly similar at the two ends, although phosphorus levels in the west end of the lake were slightly higher than in the east end. Levels of chlorophyll a increased as phosphorus levels increased, and the transparency of the water decreased as it

12 became turbid with algal cells. The water was very clear in June, but was murky with suspended algae in August. These are similar to patterns observed in the summers of 1978, 1979 and 1984. Figure 6 shows average Secchi depths and concentrations of chlorophyll a and total phosphorus for each year that has been sampled. Phosphorus data for 1978-79 are not as accurate as for other years, and should be considered only an approximation. However, the chlorophyll a data are accurate for those years, and the phosphorus data appear to be in line with chlorophyll a values. Based on the seven years of data, there has been no overall change in trophic status in the last 20 years. All lakes vary from year to year, and the range in average chlorophyll a concentrations is three-fold: on average, there was three times more algae in the water in 1979 and 1996 than in 1984. Many lake users would consider that in 1984, Wizard Lake had very good water quality, whereas in 1996 they might consider it to have poor water quality. Lakes respond to their nutrient supply for a particular year, or perhaps previous few years, so these swings in productivity are natural and typical of shallow central Alberta lakes.

3.3 NUTRIENT LOADING Sources of nutrients to Wizard Lake include spring snowmelt runoff and runoff during rain, precipitation that falls directly onto the lake, groundwater inflow, sewage effluent and the bottom sediments of the lake. Table 4 presents the original and updated phosphorus loading estimates for Wizard Lake. The amount of total phosphorus entering the lake in an average year was estimated in the early 1980s and published in The Atlas of Alberta Lakes. This phosphorus loading estimate (“Original” in Table 4) was calculated using coefficients for phosphorus loading that were derived from other studies on Alberta lakes. In these studies, the inflow stream volume and phosphorus concentrations were measured throughout the spring and summer. Then, the amount of phosphorus leaving each hectare of watershed land area over a year could be calculated (watershed phosphorus export coefficient). A similar technique was used for rain and dust that falls directly onto the lake. Coefficients derived this way were then used to calculate the long-term or average amount of phosphorus entering the lake from land areas in the Wizard Lake watershed and falling onto the lake as rain, snow and dust. The updated phosphorus loading estimates are also given in Table 4 (“Updated” column). Although the same watershed runoff phosphorus coefficients were used for the Original and Updated versions of the phosphorus loading estimates, the proportions of land under various land-use categories were revised. For the original estimate, a lower percentage of land in forest was used, even though air photos from 1981 show that the same percentage of the watershed was in forest as in recent photos (55%, as provided by the West Central Planning Agency). As well, the contribution from the watershed surrounding the shallow, slough-like part of the lake at the west end was reduced in the original version 13

80 0 CHL a TP 70 1 Secchi

60 2 * *

50 3

40 4 AND TP (µg/L) AND a 30 5 SECCHI DEPTH (m) CHL

20 6

10 7

0 8 1978 1979 1981 1982 1984 1988 1996 *1978-79 phosphorus data provisional YEAR

Figure 6. Average open-water Secchi depth and concentrations of chlorophyll a and total phosphorus in Wizard Lake 1981-84 data source – Atlas of Alberta Lakes 14

Table 4. Theoretical total phosphorus loading to Wizard Lake. Original version from Atlas of Alberta Lakes; updated version based on latest information (see text). ORIGINAL UPDATED Phosphorus, Percentage Phosphorus, Percentage SOURCE kg/year of Total kg/year of Total Watershed Forested/Bush 111 10% 164 24% Cleared/Agri. 313 30% 184 27% Urban 228 22% 89 13% (cottages,parks,etc.) Sewagea 286 27% 193 28% Precipitationb 61 6% 50 8% Inflow from Upstream Slough 52 5% ------Total External Load 1051 100% 680 100% Summer Sediment Releasec 2133 581 Total Internal Load 2133 581 TOTAL LOAD 3173 1261 a. Unmeasured – assumes all sewage effluent from cottages and camps enters lake. Original based on user estimates from 1979; updated on user estimates for 1998. b. Coefficients from Shaw et al. 1989. c. Original estimated for summer 1984 (Prepas and Shaw 1985). Updated estimated for summer 1996.

(see above). Thus, the phosphorus contribution from forested land is higher in the Updated version, while the contribution from cleared land is lower. In addition, the amount of land covered by cottages, roads, parks, etc. (“urban”) was reduced for the updated version, based on a statement in the Atlas of Alberta Lakes that 3% of the watershed is cleared for urban development. The slough connected to the lake on its northwest end may act as a sedimentation basin for phosphorus entering the lake from that part of the watershed. It appears that for the original version, it was assumed that the slough would trap a significant portion of phosphorus entering from that portion of the basin, but would release 52 kg of phosphorus to the main basin. Although this may occur for part of a year, a productive wetland such as this may contribute considerable quantities of nutrients in the spring. Therefore, for the updated version, it was assumed that the slough is part of the lake, so there is no net retention or supply of phosphorus from it. The estimates for sewage effluent were also based on information collected during other studies, rather than actually measured on Wizard Lake. The values reported in both columns in the table are based on the assumption that all sewage generated at each cottage enters the lake, and is therefore the 15

“worst case” situation. Although this is not accurate, it does give an upper limit on the potential phosphorus contribution from sewage. A phosphorus supply coefficient for human sewage was derived several years ago during a study on Baptiste Lake (0.93 kg phosphorus per person per year). This is applied to the estimated number of people using the lake in a year times the number of days everyone spends at the lake (the updated use numbers were calculated from the 1998 shoreline survey data). The same phosphorus supply coefficient for sewage was used for the original and updated estimates, but it appears that the use of the lake has decreased. It is not possible to assess the validity of the original user- year estimates; although a survey was conducted, the original data are not available. One factor that contributes to uncertainty in the updated estimate is the lack of information about how many days each user actually spends at their cottage, especially for occasional use in summer and winter. A rough estimate was used, partially based on information from the survey in the early 1980s. This is probably sufficiently accurate for this assessment. According to the new phosphorus loading calculation (“Updated” in Table 4), sewage represents a fairly large percentage of the external phosphorus load, although of course we don’t know how much, if any, actually reaches the lake. The estimates for precipitation are different for the two versions because the size of the lake was revised downward, from 2.8 km2 to 2.48 km2, and the coefficient used is slightly different, based on new information since then. The bottom sediments of the lake are a major source of phosphorus for Wizard Lake, as they are for many shallow, eutrophic lakes in central Alberta. During the warmest period of summer, phosphorus moves from the bottom mud into the water, where growing algae take advantage of the enhanced nutrient supply. The result is usually a proliferation of blue-green algae as well as an increase in phosphorus concentrations. The new calculation for the internal phosphorus supply was based on 1996 lake water quality data. This quantity can vary from year to year (Kotak and Trew 1998), so the large difference in the original and updated estimates for the bottom sediment supply is not unusual. The updated phosphorus supply estimates are lower than those calculated previously. The difference probably results from both calculation differences and lower phosphorus loading for 1996. Certainly the lower calculated internal load greatly reduces the total load for the lake. When the updated figures are compared with similar loading estimates for , Lac Ste. Anne and Lake Isle (converted to a load per square metre of lake surface), the updated estimates for Wizard are in line.

4.0 DISCUSSION AND CONCLUSIONS Water quality in Wizard Lake has not changed appreciably over the time that the lake has been sampled. This does not mean that people concerned with the lake should assume that water quality will remain the same for decades to come. Over the past 100 years or so, its phosphorus supply has 16 probably increased, because human activities in the watershed have increased. The bottom sediments likely have taken up the excess phosphorus entering the lake from clearing of the land in the watershed, presence of cattle, development of cottages and roads, malfunctioning septic systems, etc. As a result, the amount of phosphorus supplied by the bottom sediments each summer has probably also increased (Kotak and Trew 1998). This increase could continue unless steps are taken to reduce the present nutrient supply. If this could be done, the amount supplied by the sediments should eventually decline, and water quality would improve. At a minimum, the nutrient supply from outside of the lake (watershed, cottages and sewage) should not be allowed to increase. The theoretical phosphorus supply calculated for Wizard Lake suggests that there are numerous sources of phosphorus, but none are major in themselves. Thus, to control the supply of nutrients to this lake, everyone in the watershed – cottage owners, local governments, farmers, casual lake users – will have to work co-operatively. Any future development will have to be planned carefully, with nutrient control as a major objective. Sewage potentially is a major source of phosphorus for this lake. The control of nutrients from this source should be a first priority, because it is one of the easiest to control. As well, nutrients in septic leachate are highly usable by growing plants, which isn’t always true of nutrients in eroding soil. Any system that is malfunctioning, situated in inappropriate soils or too close to the lake should be corrected. There is no clear preference for one type of standard system over another. Even though it would seem that pump-out systems should intuitively be better, they tend to be abused more easily than a well constructed septic tank and field system situated in good soil. A pit privy is not a good choice if it is near the lake and receives heavy use. Generally, no septic system should be situated within 30 m of the lake, or a creek or ditch draining to the lake. All septic systems should be installed at least 1 m above the high water table. There are ways to control nutrient input from roads, construction sites, farmyards, cattle pastures, cottage property and other developed land areas. Usually this means controlling erosion. Where possible, natural vegetation – both aquatic and terrestrial - should be left in place, and cleared areas should be revegetated. Cottages should have a set-back of at least 30 metres, more if slopes are steep. Fertilizers should not be used, or should be used minimally. A cluster design for cottage development, rather than a linear arrangement along the shoreline, reduces nutrient input. Runoff from roadways should not drain directly to the lake, but should be directed toward vegetated land areas to allow runoff to evaporate and nutrients to be taken up by terrestrial plants. Cattle are potentially a large source of nutrients, but if runoff from winter feeding areas and pastures can be contained (such as in a lagoon), the impact can be greatly reduced. These techniques to control nutrient runoff from the land (called “best 17 management practices”) have been used successfully in other jurisdictions, and do not require major expenditures, especially if planned into new developments. Nutrient control in the Wizard Lake watershed has great potential for success. The lake and its watershed are small. Less than half of the watershed is cleared. The 1998 shoreline survey provides fundamental information for a water quality diagnostic study, as does the 1996 lake data. All of this information is an excellent starting point to begin detailed nutrient inventory work in the watershed. An additional year of lake water quality monitoring may be warranted. In the meantime, effort should be concentrated on cleaning up potential nutrient inputs from shoreline septic systems. One of the most productive ways to reduce nutrient input is education of lake users, concerned citizens and local governments. Most people are willing to clean up their own property if they understand how their activities can adversely affect the lake. Fundraising activities may be required for certain types of watershed cleanup projects, as occurred at . The key to maintaining water quality in Wizard Lake, or even improving it, is co-operative effort, education and patience – the latter because the effects of nutrient reduction may not be seen in the lake for several years.

5.0 LITERATURE CITED

Abraham, C. 1998. Wizard Lake hydrological and meteorological data. Water Sciences Branch, Hydrology Section Report 5DF, 98-061.

Kotak, B. and D.O. Trew. 1998. Prediction of internal phosphorus loading in shallow Alberta lakes. Water Sciences Branch, Alberta Environmental Protection, Edmonton.

Mitchell, P. and E. Prepas. 1990. Atlas of Alberta Lakes. The University of Alberta Press, Edmonton.

Prepas, E.E. and J.F.H. Shaw. 1985. Phosphorus dynamics in five shallow Alberta lakes: Hasse, Mayatan, Mink N., Mink S., Wizard. Prepared for Alberta Environment, Res. Mgt. Div., Edmonton.

Shaw, R.D., A.M. Trimbee, A. Minty, H. Fricker and E.E. Prepas. 1989. Atmospheric deposition of phosphorus and nitrogen in central Alberta with emphasis on Narrow lake. Water, Air and Soil Pollution 43: 119-134.