2012 Lakewatch Report

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Alberta Lake Management Society’s Lakewatch Program

Lakewatch has several important objectives, one of which is to collect and interpret water quality data on Alberta Lakes. Equally important is educating lake users about their aquatic environment, encouraging public involvement in lake management, and facilitating cooperation and partnerships between government, industry, the scientific community and lake users. LakeWatch Reports are designed to summarize basic lake data in understandable terms for a lay audience and are not meant to be a complete synopsis of information about specific lakes. Additional information is available for many lakes that have been included in LakeWatch and readers requiring more information are encouraged to seek those sources.

ALMS would like to thank all who express interest in Alberta’s aquatic environments and particularly those who have participated in the Lakewatch program. These people prove that ecological apathy can be overcome and give us hope that our water resources will not be the limiting factor in the health of our environment.

If you are interested in becoming a volunteer with the LakeWatch program or having your lake monitored, please email is at info@alms.ca or call us at 780-415-9785.

Acknowledgements

The LakeWatch program is made possible through the dedication of its volunteers. We would like to thank Lyall Kortzman and Jeff Hlewka for their assistance with sampling Muriel Lake in 2012. We would also like to thank Randi Newton and Erin Rodger who were summer technicians with ALMS in 2012. Program Coordinator Bradley Peter was instrumental in planning and organizing the field program. Technologists Trina Ball and Brian Jackson were involved in the training aspects of the program. Lisa Reinbolt was responsible for data management. This report was prepared by Bradley Peter. and Arin Dyer. Alberta Environment and the Beaver River Watershed Alliance (BRWA) were major sponsors of the program.

Historical data has been re-queried and summarized for the 2012 report.

 

Muriel Lake:murielLake

Muriel Lake is located 13 km south of the town Bonnyville and 250 kn northeast of
Edmonton. The first establishment in the area by non-aboriginal peoples was a fur-trading post in 1781 by the North West Company near the present-day hamlet of Beaver Crossing, about 35 km northeast of Muriel Lake. The first settlers came to the Bonnyville area in 1907 and established an economy based on the timber industry. Two sawmills were located at Muriel Lake, one at the northeastern tip and the other on the large island/peninsula on the eastern shore. In the 1920’s, a large fire forced the economic base to switch to agriculture.

There are several subdivisions (391 lots) around the lakeshore, mostly on the south and east sides of the lake. Much of the watershed is occupied by the Kehewin Cree Nation Reserve 123, located on 8200 ha of land southwest of the lake. The largest recreational facility on Muriel Lake is Muriel Lake Park, which is operated by the Municipal District of Bonnyville. Northern pike, yellow perch, lake whitefish, and walleye were once prevalent in the lake, however these fish are no longer stocked, and a 2012 netting of the lake performed by the Environment and Sustainable Resource Development revealed no sport fishes are present in Muriel Lake; only brook stickleback and longnose suckers were captured in 2012 netting(1). Low winter dissolved oxygen levels (3.0 mg/L) leaves Muriel Lake at a high risk for fish kills(1).

Muriel Lake is a large (64.1 km2) but shallow water (average depth?) body with a relatively small drainage basin, measuring only 4.8 times the size of the lake area. The shorelines consist primarily of steep rocky slopes, but there are also several attractive sandy beaches. Water levels have been monitored since the late 1960’s and since then have dropped by as much as 4.5 m. Muriel Lake has a relatively low concentration of algae and mixes periodically throughout the summer.


 

1. Latty, D. 2012 Muriel Lake Walleye Index Netting, 2012. Alberta Enviroment and Sustainable Resource Development, Retrieved on February 21st, 2012 from http://srd.alberta.ca/FishWildlife/FisheriesManagement/FallWalleyeIndexNetting/Default.aspx

 

Water Quantity:

There are many factors influencing water quantity. Some of these factors include the size of the lakes drainage basin, precipitation, evaporation, water consumption, ground water influences, and the efficiency  of the outlet channel at removing water from the lake. 

Water levels at Muriel Lake have declined steadily over the past 30 years (Figure 2). Since 1980, water levels have dropped from 559.744 m asl to 555.861 m asl, or approximately four meters. Such a decline is though to be unprecedented at Muriel Lake(2) and has been the topic of recent Alberta Environment studies. Conclusions from these studies , the results of which were presented at a Muriel Lake Basin Management Society annual general meeting, have suggested that Muriel Lake is a net groundwater gaining lake and that declines in water levels are due primarily to changes in climate, including both reduced precipitation and increased temperatures(3,4). Members of the Muriel Lake Basin Management Society are interested in completing further studies to determine if development activities in the drainage basin have had any effect on lake levels Concerns over the effects of reduced water levels on the lake water quality prompted residents to have ALMS conduct monitoring in 2012.

figure2(2012report)


2. Donohue, W. F., 2006. Historical Interpretation of Water Supply to Muriel Lake in the 20th century. Freshwater Research Ltd.

3. Welsh, B. July 8th, 2012. Groundwater in the Muriel Lake Watershed. Muriel Lake Basin Management Society Annual General Meeting. Presentation conducted from the Bonnyville and District Centennial Centre, Bonnyville, Alberta.

4. Kerkhoven, E. July 8th, 2012. Muriel Lake Hydrology. Muriel Lake Basin Management Society Annual General Meeting. Presentation conducted from Bonnyville and District Centennial Cenre, Bonnyville, Alberta.

 

Water Clarity and Secchi Depth:

Water clarity is influenced by suspended materials, both living and dead, as well as dissolved colored compounds in the water column. During the melting of snow and ice in the spring, lake water can become turbid (cloudy) from silt transported into the lake. Lake water usually clears in late spring but then becomes more turbid with increased algal growth as the summer progresses. The easiest and most widely used measure of lake water clarity is the Secchi disk depth.

Average Secchi disk depth at Muriel Lake during the summer of 2012 measured 2.86 m. This is the highest average Secchi depth measured at Muriel Lake by ALMS and Environment and Sustainable Resource Development. Throughout the summer, Secchi disk depth ranged from a maximum 4.25 m on June 4th to a minimum of 1.75 m in September 16th. Secchi disk depth appeared to respond closely to changes in chlorophyll-a concentration, suggesting that algae/cyanobacteria was the primary factor affecting water clarity in 2012. The concentration of total suspended solids was relatively low throughout the summer, averaging 2.66 mg/L.

Water Temperature and Dissolved Oxygen:

Water temperature and dissolved oxygen profiles in the water column can provide information on water quality and fish habitat. The depth of the thermocline is important in determining the depth to which dissolved oxygen from the surface can be mixed. Please refer to the end of this report for descriptions of technical terms.

Surface water temperature changed throughout the summer from a minimum of 13.12°C on September 16th to a maximum of 21.73°C on July 24th (Figure 3a). No thermal stratification was observed on any of the sampling trips – though it is possible that thermal stratification does develop on warm, calm days. Temperature of the water column, specifically the presence/absence of thermal stratification, has the potential to impact dissolved oxygen concentrations.

figure3(2012report)Surface dissolved oxygen concentrations at Muriel Lake changed greatly throughout the course of the summer, measuring a minimum of 6.27 mg/L on August 3rd and a maximum of 9.26 mg/L on September 16th (Figure 3b). On August 3rd the entire water column fell below the Canadian Council for Ministers of the Environment (CCME) guidelines for the Protection of Aquatic Life of 6.50 mg/L. Near the lakebed, dissolved oxygen concentrations consistently declined during each sampling trip; the decomposition of organic matter on the lakebed, an oxygen-consuming process, contributes to this decline.

Water Chemistry:

ALMS meaures a suite of water chemistry parameters. Phosphorus, nitrogen, and chlorophyll-a are important because they are indicators of eutrophication, or excess nutrients, which can lead to harmful algal/cyanobacteria blooms. One direct measure of harmful cyanobaceria blooms are Microcystins, a common group of toxins produced by cyanobacteria. See Table 1 for a complete list of parameters.

Average Total Phosphorus (TP) measured 54.2 μg/L during the summer of 2012 (Table 1). This value falls into the eutrophic, or nutrient rich, classification. While this value is comparable to measurements taken in 2006 and 2009, this average seems elevated when compared to measurements recorded in the 1980’s and 1990’s. Phosphorus levels may have become concentrated with declines in water levels, though the interactions that occur at the sediment-water interface are also important factors in the phosphorus cycle. More data is required from the lake if proper statistical evaluations of trends in water quality are to be conducted.

Average chlorophyll-concentration, an indicator of algal/cyanobacterial biomass, meausred 4.59 μg/L in 2012 (Table 1). This average is the lowest measured at Muriel Lake and falls into the mesotrophic, or moderately productive classification. Though increased phosphorus concentrations might suggest increased chlorophyll-a concentrations, parallel increases in ion concentration and conductivity have occured which likely inhibit the growth of algae/cyanobacteria. Throughout the summer, chlorophyll-concentration ranged form a minimum of 0.61 μg/L on June 4th, to a maximum of 7.68 μg/L on September 16th (Figure 5).

Average total Kjeldahl nitrogen measured at Muriel Lake in 2012 was 3130 μg/L – this value falls well into the hypereutrophic classification. As with phosphorus, levels of TKN appear to have increased when compared to historical measurements – again, this is likely due to the concentration of nutrients due to water loss.

figure5(2012report)

Average pH at Muriel Lake measured 9.19 well above neutral (Table 1). Muriel Lake has very high alkalinity (1050 mg/L CaCO³) and bicarbonate (926.6 mg/L) concentrations which help to buffer the lake against changes to pH. Concentrations of alkalinity and bicarbonate appear to have increased when compared to historical values. Similarly, conductivity at Muriel Lake is quite high, measuring 2212 uS/cm, and this high conductance may inhibit the growth of algae/cyanobacteria. Dominant ions in Muriel Lake include sodium (283.3 mg/L) and magnesium (154.7 mg/L).

Metals were measured twice at Muriel Lake and all metals sampled for, with thet exception of arsenic, fell within the recommended CCME guidlines (Table 2). Arsenic measured an average of 8.72 μg/L, which exceeds the recommended CCME guidline of 5.0 μg/L for the Protection of Aquatic Life; however, lakes in the Beaver River Watershed are known to have elevated levels of arsensic. Finally, microcystin, a toxin produced by algae/cyanobacteria, meausured 0.36 μg/L, well below the recommended recreational guidlines (20 μg/L).

table1(2012report)

table2(2012report)

A Brief Introduction To Limnology

Indicators of Water Quality:

Water samples are collected in LakeWatch to determine the chemical characteristics that characterize general water quality. Though not all encompassing, the variables collected in LakeWatch are sensitive to human activities in watersheds that can cause degraded water quality. For example, nutrients such as phosphorus and nitrogen are important determinants of lake productivity. The concentrations of these nutrients in a lake are impacted (typically elevated) by land use changes such as increased crop production or livestock grazing. Elevated nutrient concentrations can cause increases in undesirable algae blooms resulting in low dissolved oxygen concentrations, degraded habitat for fish and noxious smells. A large increase in nutrients over time may also indicate sewage inputs which in turn may result in other health concerns associated with bacteria or the protozoan Cryptosporidium.

Temperature and Mixing:figure3a(2012report)

Water temperature in a lake dictates the behavior of many chemical parameters responsible for water quality.
Heat is transferred to a lake at its surface and slowly moves downward depending on water circulation in the lake. Lakes with a large surface area or a small volume tend to have a greater mixing due to wind. In deeper lakes, circulation is not strong enough to move warm water to depths typically greater than 4 or 5 m and as a result cooler denser water remains at the bottom of the lake. As the difference in temperature between warm surface and cold deeper water increases, two distinct layers are formed. Limnologists call these layers of water the epillimnion at the surface and the hypolimnion at the bottom. The layers are separated by a transition layer known as the metalimnion which contains the effective wall separating top and bottom waters called a thermocline. A thermoclibe typically occurs when water temperature changes by more than one degree within one meter depth. The hypolimnion and epilimnion do not mix, nor do elements such as oxygen supplied at the surface move downward into the hypolimnion. In the fall, surface waters begin to cool and eventually reach the same temperature as hypolimnetic water. At this point the water mixes from top to bottom in what is often called a turnover event. Surface water cools as ice forms and again a thermocline develops this time with 4°C water at the bottom and near 0°C water on the top.

In spring another turnover event occurs when surface water warm to 4°C. Lakes with this mixing pattern of two stratification periods and two turnover events are called dimictic lakes. In shallower lakes, the water column may mix from top to bottom most of the ice-free season with occasional stratification during periods of calm warm conditions. Lakes that mix frequently are termed polymictic lakes. In our cold climate, many shallow lakes are cold monomictic meaning a thermocline develops every winter, there is one turnover event in spring by the remainder of the ice free season the lake is polymictic.

Dissolved Oxygen:

Oxygen enters a lake at the surface and throughout the water column when produced by photosynthesizing plants, including algae, in the lake. Oxygen is consumed within the lake by respiration of living organisms and decomposition of organic material in the lake sediments. In lakes the stratify (see temperature above), oxygen that dissolves into the lake at the surface cannot mix downward into the hypolimnion. At the same time oxygen is depleted in the hypolimnion by decomposition. The result is that the hypolimnion of a lake can become anoxic, meaning it contains little or no dissolved oxygen. When a lake is frozen, the entire water column can become anoxic because the surface is sealed off from the atmosphere. Winter anoxic conditions can result in a fish-kill which is particularly common during harsh winters with extended ice-cover. Alberta Surface Water Quality Guidlines suggest dissolved oxygen concentrations (in the epilimnion) must not decline below 5 mg•L^-1 and should not average less than 6.5 mg•L^-1 over a seven-day period. However, the guidlines also require that dissolved oxygen concentrations remain above 9.5 mg•L^-1 in areas where early life stages of aquatic biota particularly fish, are present.

General Water Chemistry:

Water in lakes always contains substances that have been transported by rain and snow or have entered the lake in groundwater and inflow streams. These substances may be dissolved in the water or suspended as particles. Some of these substances are familiar minerals, such as sodium and chloride, which when combined form table salt, but when dissolved in water, separate into the two electrically charged components called ions. Most dissolved substances in water are in ionic forms and held in solution due to the polar nature of the water molecule. Hydrophobic (water-fearing) compounds such as oils contain little or no ionic character, are non-polar and for this reason, do not readily dissolve in water. Although hydrophobic compounds do not readily dissolve, they can still be transported to lakes by flowing water. Within individual lakes, ion concentrations vary from year to year depending on the amount and mineral content of the water entering the lake. This mineral content can be influenced by the amount of precipitation and other climate variables as well as human activities such as fertilizer and road salt application.

Phosphorus and Nitrogen:

Phosphorus and nitrogen are important nutrients limiting the growth of algae in Alberta lakes. While nitrogen usually limits agricultural plants, phosphorus is usually in shortest supply in lakes. Even a slight increase of phosphorus in a lake can, given the right conditions, promote algal blooms causing the water to turn green in the summer and impair recreational uses. When pollution originating from a livestock manure and human sewage enters lakes not only become a limiting nutrient which is thought to cause blooms of toxic algae belonging to the cyanobacteria. Not all cyanobacteria are toxic, however, the blooms can form decomposing mats that smell and impair dissolved oxygen concentrations in the lake.

Chlorophyll-a:

Chlorophyll is a photosynthetic pigment that green plants, including algae, possess enabling them to convert the sun’s energy to living material. Chlorophyll can be easily extracted from algae in the laboratory. Consequently, chlorophyll a is a good estimate of the amount of algae in the water. Some highly productive lakes are dominated by larger aquatic plants rather than suspended algae. In these lakes, chlorophyll and nutrient values taken from water samples do not include productivity from large aquatic plants. The result, in lakes like Chestermere which are dominated by larger plants known as macrophytes, can be a lower trophic state than if macrophyte biomass was included. Unfortunately, the productivity and nutrient cycling contributions of macrophytes are difficult to sample accurately and are therefore not typically included in trophic state indices.

Secchi Disk Transparency:

Lakes that are clear are more attractive for recreation, whereas those that are turbid or murky are considered by lakes users to have poor water quality. A measure of the transparency or clarity of the water is performed with a Secchi disk with an alternating black and white pattern. To measure the clarity of the water, the Secchi disk is lowered down into the water column and the depth where the disk disappears is recorded. The Secchi depth in lakes with a lot of algal growth will be small while the Secchi depths are not caused by algal growth can be very deep. Howver, low Secchi depths are not caused by algal growth alone. High concentrations of suspended sediments, particularly fine clays or glacial till, are common in plains or mountain reservoirs of Alberta. Mountain reservoirs may have exceedingly low Secchi depths despite low algal growth and nutrient concentrations.

The euphotic zone or the maximum depth that light can penetrate into the water column for actively growing plants is calculated as twice the Secchi depth. Murky waters, with shallow Secchi depths, can prevent aquatic plants from growing on the lake bottom. Conversely, aquatic plants can ensure lakes have clear water by reducing shoreline erosion and stabilizing lake bottom sediments. In Alberta, many lakes are shallow and bottom sediments contain high concentrations of nutrients. Without aquatic plants, water quality may decline in these lakes due to murky, sediment laden water and excessive algal blooms. Maintaining aquatic plants in certain areas of a lake is often essential for ensuring good water clarity and a healthy lake as many organisms, like aquatic invertebrates and insects, depend on aquatic plants for food and shelter.

Trophic State:figureb(2012report)

Trophic state is classification of lakes into four categories of fertility and is a useful index for rating and comparing lakes. From low to high nutrient and algal biomass (as chlorophyll) concentrations, the trophic states are olligotrophic, mesotrophic, eutrophic and hypereutrophic (Table 2). 

A majority of lakes in Alberta contain naturally high levels of chlorophyll a (8 to 25 μg/L) due to our deep fertile soils. These lakes are usually considered fertile and are termed eutrophic. The nutrient and algal biomass concentrations that define these categories are shown in the following table, a figure of Alberta lakes compared by tropic state can be found in the ALMS website.

tablea(2012report)