THE ALBERTA LAKE MANAGEMENT SOCIETY VOLUNTEER LAKE MONITORING PROGRAM 2015 Pigeon Lake Report LAKEWATCH IS MADE POSSIBLE WITH SUPPORT FROM: 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. Data in this report is still in the validation process. Acknowledgements The LakeWatch program is made possible through the dedication of its volunteers. We would like to thank Richard McCardia and Colin McQueen for volunteering to sample Pigeon Lake in 2015. In addition, we would like to thank the Pigeon Lake Watershed Association and its contributing members and Summer Villages for their assistance in program coordination and financial support. We would also like to thank Laticia McDonald, Ageleky Bouzetos, and Mohamad Youssef who were summer technicians with ALMS in 2015. Executive Director Bradley Peter was instrumental in planning and organizing the field program. Mike Bilyk was involved in the training aspects of the program. Lisa Reinbolt was responsible for data management. This report was prepared by Bradley Peter and Alicia Kennedy. The Beaver River Watershed Alliance (BRWA), the Lakeland Industry and Community Association (LICA), the Alberta Environmental Monitoring Evaluation and Reporting Agency (AEMERA), and Environment Canada, were major sponsors of the program. PIGEON LAKE: Pigeon Lake is a large (96.7 km2), shallow (average depth = 6m) lake located in the counties of Wetaskiwin and Leduc. It is a very popular recreational lake within easy driving distance from the cities of Edmonton, Leduc, and Wetaskiwin. Pigeon Lake lies within the Battle River watershed. Water flows into the lake through intermittent streams draining the west and northwest portions of the watershed. The outlet, Pigeon Lake Creek, at the southeast margin of the lake, drains toward the Battle River.1 The lake’s drainage basin is small (187 km2) but heavily developed with agriculture, oil and gas, as well as recreational development throughout the watershed. The lake name is a translation from the Cree Mehmew Sâkâhikan, which means ‘Dove Lake’, but by 1858 the name Pigeon Lake was in use.2 It has been suggested that the name Pigeon Lake refers to the huge flocks of Passenger Pigeons that once ranged in the area.1 The lake was also previously known as Woodpecker Lake, and the Stoney name is recorded as Ke-gemni-wap-ta.2 The water quality of Pigeon Lake is typical of large, productive, shallow lakes in Alberta, with water remaining quite green for most of the summer. However, residents have recently expressed concern over perceptions of deteriorating water quality as 1 a result of recurring toxic Figure 1 – Bathymetric map of Pigeon Lake. blue-green algal blooms, fish kills, and beach advisories3. Due to these concerns, there has been a demand to examine ways to reduce the frequency and intensity of cyanobacteria blooms. In 2013, data was collected to prepare a nutrient budget for Pigeon Lake, this report was later released in 2014 and it outlines areas of interest when considering watershed and in-lake management options 4. Out of the total phosphorus entering 1 Mitchell, P. and E. Prepas. 1990. Atlas of Alberta Lakes, University of Alberta Press. Retrieved from http://sunsite.ualberta.ca/projects/alberta-lakes/ Aubrey, M. K. 2006. 2 Aubrey, M. K. 2006. Concise place names of Alberta. Retrieved from http://www.albertasource.ca/placenames/resources/searchcontent.php?book=1 3 Aquality Environmental Consulting. 2008. Pigeon Lake State of Watershed Report. Prepared for Pigeon Lake Watershed Alliance. Retrieved from: www.plwa.ca. 4 Teichreb, C.2014. Pigeon Lake Phosphorus Budget. Alberta Environment and Sustainable Resource Development. 28 pp. the lake, 56% comes from internal loading and 43% coming from external watershed sources. The major contributors to external loading were dust fall and precipitation (43%), and diffuse inflows (48%). The remaining external sources of phosphorus come from streams (6%), sewage (2%), and groundwater (1%)4. 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 structure at removing water from the lake. Requests for water quantity monitoring should go through Alberta Environment and Parks Science and Monitoring division or through Environment Canada. Visit https://wateroffice.ec.gc.ca and www.rivers.alberta.ca for more information. Water levels in Pigeon Lake tend to fluctuate within a one-meter interval (Figure 2). Because the watershed of Pigeon Lake is relatively small, only twice the size of the lake area, water levels in Pigeon Lake are likely influenced by ground water input. There has been a general trend towards decline in water quantity since the early 1980’s. 850.4 850.3 850.2 850.1 850 849.9 849.8 849.7 Water Level (m Water Level (m asl) 849.6 849.5 849.4 1960 1970 1980 1990 2000 2010 2020 Year Figure 2 – Averages of historical monthly mean water levels (m asl) available through Environment Canada at https://wateroffice.ec.gc.ca via station code 05FA013. Data available until 2015. 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 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 depth measured 1.65 m in 2015 (Table 2). This average fall on the low end of the historical variation observed at Pigeon Lake (1.38 m–4.42 m). Throughout the summer, Secchi depth closely tracked the concentration of chlorophyll-a, highlighting the impact the phytoplankton blooms have on water clarity (Figure 3). A maximum Secchi depth of 2.70 m was observed on June 23rd while a minimum Secchi disk depth of 0.60 m was observed on August 19th. Date 23-Jun 27-Jul 19-Aug 01-Sep 18-Sep 0 0.5 0.60 1 1.5 1.50 1.60 2 1.85 Secchi Depth (m) Depth Secchi 2.5 3 2.70 Figure 3 – Secchi disk depth measured five times over the course of the Summer at Pigeon Lake. 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 measured a maximum of 20.70 °C (Figure 4a). Throughout the water column, temperature remained un-stratified – this has important implications for dissolved oxygen concentrations. Deep waters often act as refuge for fish from warm temperatures – in 2015, the maximum observed temperature at the lake sediment measured 18.69 °C on July 27th. By September 18th, the temperature of the water column had dropped significantly, measuring only 13.75 °C at the lake surface. a) b) Temperature (°C) Dissolved Oxygen (mg/L) 0 10 20 30 0 5 10 15 0 0.0 23-Jun 23-Jun 1.0 1 27-Jul 27-Jul 2 19-Aug 2.0 19-Aug 1-Sep 1-Sep 3 3.0 18-Sep 18-Sep 4 4.0 5 (m) Depth 5.0 Depth (m) Depth 6 6.0 7 7.0 8 8.0 9 9.0 10 10.0 Figure 4 – a) Temperature (°C) and b) dissolved oxygen (mg/L) profiles measured five times over the course of the summer of 2015. Dissolved oxygen concentrations remained well above the Canadian Council for Ministers of the Environment guidelines for the Protection of Aquatic Life of 6.5 mg/L for much of the water column throughout 2015 (Figure 4b). Concentrations at the surface appeared slightly elevated due to phytosynthetic activity on August 19th Due to probe malfunction, oxygen data was not obtained on September 18th. Anoxia was not observed, though sharp decreases in oxygen concentration were observed near the sediment. In contrast, in 2014 thermal stratification resulted in a dramatic decline in oxygen concentration. Anoxia near the lake sediment can result in the release of phosphorus from lake sediments. WATER CHEMISTRY: ALMS measures a suite of water chemistry parameters. Phosphorous, 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 cyanobacteria blooms are Microcystins, a common group of toxins produced by cyanobacteria. See Table 1 for a complete list of parameters.