Hutchinson Environmental Sciences Ltd. Technical Update for the Lesser Slave Watershed Prepared for: Lesser Slave Watershed Council Job #: J140058 May 25, 2015 1-5 Chancery Lane, Bracebridge ON, P1L 2E3 │ 705-645-0021 Suite 202 – 501 Krug Street, Kitchener, ON N2B 1L3 │ 519-576-1711 4482 97 St. NW. Edmonton AB, T6E 5R9 │587-773-4850 Hutchinson Environmental Sciences Ltd. 4482 97 St. NW. Edmonton AB, T6E 5R9 │587-773-4850 www.environmentalsciences.ca May 25, 2015 HESL Job #: J140058 Meghan Payne Executive Director Lesser Slave Watershed Council 204A 4723 53 Ave, High Prairie, AB T0G 1E0 Dear Ms. Payne: Re: Technical Update for the Lesser Slave Watershed We are pleased to submit this final report to you that presents the Technical Update for the Lesser Slave Watershed. The report has incorporated a variety of information available to us from different sources as well as two reports prepared by third parties. The key elements of the reports are as follows: 1) An aquatic assessment of rivers and the lake, including information on flow and water quality, 2) A Phosphorus budget for Lesser Slave Lake based on different methods, 3) A summary of paleolimnological data collected from two studies describing historical lake water quality, including previously analyzed (geochemistry, pigments) and raw (organic contaminant, diatom) data, 4) A BATHUB modeling exercise to predict lake water quality based on the P budget and future development and restoration scenarios, prepared by ESRD and NSWA, and 5) A summary of fisheries status and human limitations that affect them, prepared by ESRD. We thank you for the opportunity to assist you with this interesting assignment and look forward to presenting the results at LSWC’s annual meeting. Sincerely, Hutchinson Environmental Sciences Ltd. Dörte Köster, Ph.D. [email protected] R250515_J140058_LSL_Final.docx J140058, Lesser Slave Watershed Council Technical Update for the Lesser Slave Watershed Signatures Report Prepared by: Christine Geiger, M.Sc. Aquatic Scientist Dörte Köster, Ph.D. Senior Aquatic Scientist Tammy Karst-Riddoch, Ph.D. Senior Aquatic Scientist Report Reviewed by: Andrea Smith, Ph.D. Senior Ecologist With contributions from Faye Wyatt, Fiera Biological Consulting: Mapping and Land Cover Analysis, German Rojas (Alberta Environment and Sustainable Resource Development (ESRD): Lake Water Budget Modelling, Alyssa Tuininga (ESRD): BATHTUB Modelling and reporting, David Trew (North Saskatchewan Watershed Alliance): BATHTUB Modelling review, Kristy Wakeling and Miles Brown (ESRD), Fisheries data analysis and reporting, and Roderick Hazewinkel (Alberta Environment and Sustainable Resource Development) and Collin Cooke (Alberta Environmental Monitoring, Evaluation and Reporting Agency, AEMERA): Paleolimnological data collection and interpretation. Hutchinson Environmental Sciences Ltd. R100615_J140058_LSL_Final.docx ii J140058, Lesser Slave Watershed Council Technical Update for the Lesser Slave Watershed Acknowledgements We would like to thank Kristy Wakeling and Myles Brown for completing the fisheries section of this report and for responding to our comments and questions in detail, helping us understand the significance of the findings. A large “Thank You” goes to Alyssa Tuininga from Alberta Environment and Sustainable Resource Development (ESRD), who set up, ran and reported on the BATHTUB model for Lesser Slave Lake and agreed to run alternative scenarios. Dave Trew from the North Saskatchewan Watershed Alliance supervised the BATHTUB work, helped clarify the results though constructive discussions and provided senior review of the BATHTUB report section. We also thank German Rojas from ESRD for modeling the Lesser Slave Lake water budget required for the BATHTUB modeling exercise and for responding to our questions and comments in detail. Roderick Hazewinkel (ESRD) and Collin Cooke (AEMERA) provided the paleolimnological data and draft interpretive reports. We thank Faye Wyatt from Fiera Biological Consulting for creating informative maps and for providing land cover information and burnt areas for the export-coefficient based phosphorus budget. Laura Taylor from Shared Values Solutions Ltd. created a wonderful public document based on the findings of this technical report. Our discussions on key messages of the study helped us to improve the presentation of this technical report. At the draft report stage, Jana Tondu and German Rojas (ESRD) provided constructive comments on this document, which helped increase clarity and technical detail. Meghan Payne administered this project in her function as executive director of the LSWC, and together with her fellow members provided insightful comments on the draft public document. We would like to acknowledge funding provided to the LSWC for this project by the Government of Alberta, Big Lakes County, the Smokey Applied Research and Demonstration Association, MD of Lesser Slave River and the North Saskatchewan Watershed Alliance. Hutchinson Environmental Sciences Ltd. R100615_J140058_LSL_Final.docx iii J140058, Lesser Slave Watershed Council Technical Update for the Lesser Slave Watershed Executive Summary The Lesser Slave Watershed Council (LSWC) works toward maintaining the health of the Lesser Slave Watershed to ensure safe, secure drinking water; healthy aquatic ecosystems; and reliable, unpolluted water supplies for a sustainable future. Its responsibilities are, amongst others, to report on watershed health. Since the first State of the Watershed report (Jamison 2009), more data has been collected and the purpose of this report is to summarize and interpret these data. This technical update includes an aquatic assessment of the lake and rivers, a phosphorus budget for the lake, a BATHTUB model of lake phosphorus under current conditions and hypothetical land use scenarios, an interpretation of sediment (paleolimnological) data to assess historic trends in water quality, and an update on the state of fish populations in the lake and rivers. River Flow River flows were described in order to understand any variations in water quality related to flow. River flows varied strongly with season and among watersheds. A seasonal pattern of lowest flow during winter and high flows during spring runoff was common to all watersheds. Subwatersheds that are partly situated in the foothills, however, displayed another flow peak in summer due to mountain snow melt. These peaks were larger with larger foothills areas in the watersheds, as shown in Swan River, and smaller in watersheds with little foot hill influence, such as WPR. River Water Quality Water quality data for the main rivers (West and East Prairie, South Heart, Driftpile and Swan Rivers) collected between 2007 and 2013 were analyzed and consisted of 3 to up to 13 sampling events per site, originating from various open-water seasons. Since these sampling events were spread over years and seasons, the dataset is quite limited in scope and the conclusions drawn here should be confirmed through additional sampling. Rivers had moderate alkalinity and were elevated in nutrients, which is typical for Alberta boreal streams, due to the soil characteristics in this region. River water quality varied considerably among rivers and seasons, with the largest differences associated with varying seasonal flows and, to a lesser extent, water source. Smaller variations were observed among subwatersheds. Spring and summer peak flows resulted in largest TSS, TP and total metal concentrations due to watershed and riverbed erosion and lowest alkalinity due to large inputs of snowmelt. Total metal concentrations associated with suspended sediments regularly exceeded water quality guidelines for the protection of aquatic life. Although it can be assumed that this is a natural occurrence in these rivers, increases in suspended sediments due to landscape and channel modifications may have increased the metal loads as well. The largest spring peaks in sediment-associated parameters were observed in East Prairie River, whose flow patterns have been severely altered by channelization and diking, demonstrating the effect these modifications have on water quality. Driftpile and Swan River, while similar to other rivers in terms of TSS and total metal patterns, had the lowest TP and DP concentrations, likely due to the lower extent of agriculture in these watersheds. Hutchinson Environmental Sciences Ltd. R250515_J140058_LSL_Final.docx iv J140058, Lesser Slave Watershed Council Technical Update for the Lesser Slave Watershed Seasonal differences were less pronounced in South Heart River, due to the influence of slower, low gradient flow in the delta. In exchange, the South Heart River showed the highest median and fall TP concentrations among all LSL tributaries, possibly due to larger watershed inputs from agricultural lands or the slower flows in the lower SHR, which may allow more extensive phytoplankton growth than in the other, faster-flowing rivers. Lesser Slave River showed substantially different water quality patterns than the other rivers, because it is composed of LSL outflow water. LSR had relatively stable water quality over the season and much lower concentrations of parameters associated with suspended sediments. Phosphorus Budget A phosphorus budget was developed to quantify all known sources of phosphorus to Lesser Slave Lake and gain a greater understanding of how watershed management could influence lake phosphorus levels and future algal blooms. The phosphorus sources included