CREDIT VALLEY CONSERVATION LAKE ONTARIO INTEGRATED SHORELINE STUDY BACKGROUND REVIEW AND DATA GAP ANALYSIS APPENDIX D Water Quality Final Report Prepared By: AQUAFOR BEECH LIMITED #6-202-2600 Skymark Ave Mississauga, ON L4W 5B2 May 5, 2011 Project No.: 64967 Water Quality Report Lake Ontario Integrated Shoreline Study Table of Contents 1 Introduction ............................................................................................................................... 3 2 Background Information ........................................................................................................... 5 2.1 The 1960s – PWQMN and the IJC ................................................................................. 5 2.2 The 1970s – GLWQA and PLUARG ............................................................................. 5 2.3 The 1990s – Watershed Studies...................................................................................... 7 2.4 The 2000s – Water Quality in the Nearshore................................................................ 11 3 Sediments ................................................................................................................................ 18 4 Beach Closures........................................................................................................................ 19 5 Data Assessment...................................................................................................................... 20 5.5 Water Quality Monitoring Stations............................................................................... 20 5.6 Contaminant Loadings.................................................................................................. 21 5.7 Nearshore versus Offshore Data ................................................................................... 25 5.8 Lake Ontario Circulation .............................................................................................. 28 5.9 Lake Hydrodynamics.................................................................................................... 29 6 Historic Phosphorous Concentrations for Credit river............................................................ 31 7 Information Gaps..................................................................................................................... 34 8 References ............................................................................................................................... 36 List of Tables Table 1: LOISS Watersheds Draining into Lake Ontario............................................................... 4 Table 2: City of Mississauga Sewersheds Areas Draining into Watercourses and into Lake Ontario....................................................................................................................................... 4 Table 3: PWQMN and IWMP water chemistry stations and sediment chemistry stations .......... 19 Table 4: Beach Closures 2006-2009............................................................................................. 20 Table 5: PWQMN and CVC IWMP Stations ............................................................................... 20 Table 6: Detailed sampling locations in the Credit Valley Watershed......................................... 21 Table 7: Nearshore and Offshore Water Quality data (Means and ranges of values) from U.S. EPA Mid-Continent Division (Duluth MN) and E.S. EPA GLNPO. Data from 2002 – 2007 (SOLEC, 2009)........................................................................................................................ 26 List of Figures Figure 1: Annual TP Loadings (Welland Canal to Oakville Creek). Bill Booty (submitted to JGLR). ..................................................................................................................................... 22 Figure 2: Annual TP Loadings (Wedgewood Creek to Pringle Creek). Bill Booty (submitted to JGLR). ..................................................................................................................................... 23 Figure 3: Annual TP Loadings (Oshawa Creek to Farewell Creek). Bill Booty (submitted to JGLR). ..................................................................................................................................... 23 Figure 4: Daily TP Loadings to Lake Ontario from Duffins Creek at WPCP for 2007 and 2008 (University of Waterloo 2009) ................................................................................................ 24 Figure 5: Annual TP Loadings to Lake Ontario from Duffins Creek at WPCP for 2007 and 2008 (University of Waterloo 2009) ................................................................................................ 25 Figure 6: Annual Dry and Wet Total Phosphorous from Watercourses, Storm Sewers Discharging Directly to Lake Ontario and Wastewater Treatment Plant Effluent.................. 25 Aquafor Beech Limited 1 Water Quality Report Lake Ontario Integrated Shoreline Study Figure 7: Nearshore Sampling Locations in the Toronto to Ajax Area in 2008........................... 26 Figure 9 Total Phosphorus (TP) and Total Filtered Phosphorus in the Nearshore Lake Ontario at stations within 10 kilometres of the Toronto Waterfront ........................................................ 28 Figure 10: Total Phosphorus (TP) and Total Filtered Phosphorus in the Offshore Lake Ontario at stations within 10 kilometres of the Toronto Waterfront ........................................................ 28 Figure 11: Mean Circulation Patterns and Average Velocities in Lake Ontario from May to September 2007....................................................................................................................... 29 Figure 12: Mean Circulation Patterns and Average Velocities in Lake Ontario from May to September 2007....................................................................................................................... 29 Figure 13: Intake Protection Zone (IPZ) for Lakeview and Clark Water Treatment Plants......... 30 Figure 14: Time Trends in mean annual phosphorus in the Credit River and Fletcher’s Creek (1964-2000). ............................................................................................................................ 32 Figure 15: Conceptual Phosphorus Cycle in Freshwater Lakes with Zebra Mussels................... 33 Aquafor Beech Limited 2 Water Quality Report Lake Ontario Integrated Shoreline Study 1 INTRODUCTION It is important to know what the 13 urbanized and urbanizing watersheds within the Credit Valley Conservation jurisdiction are discharging into Lake Ontario and how the lake is coping. Some long-term trends are available to see what has changed, or is changing and where we should look if we want to do something about it. In most cases, phosphorus has been a key water quality parameter and has been cited as the culprit when things go visibly awry, whether it is the loss of prey fish, the resurgence of nuisance algae, taste & odour episodes in drinking water or beach closures. There have been two major ecosystem perturbations of the Great Lakes over the past 40 years that have consequences on water quality. Both of these involve phosphorus. The first, in the 1970s, came about with the reduction in phosphorus inputs due to two near-simultaneous events: (1) the regulatory decrease in the phosphate content of detergents; and , (2) Implementation of the bi-national Great Lakes Water Quality Agreement to reduce phosphorus in water pollution control plant (WPCP) effluents to 1 mg/L. The second perturbation resulted from the explosive growth of invasive species in the 1990s, particularly as the dressenid (zebra and quagga) mussels, along with other creatures, such as the spiny (or fish hook) water flea ( Cercopagis pengoi ), a predatory cladoceran that feeds on zooplankton. Paradoxically, and perhaps as a result, phosphorus concentrations in Lake Ontario have decreased over the last four decades: the lake has become more oligotrophic, water clarity has improved, zooplankton concentrations have decreased offshore and phytoplankton production has decreased 1. Paradoxically, there has been a resurgence of nuisance algae ( Cladophora glomerata ). This section reviews the water quality studies on Lake Ontario tributaries and for the nearshore and offshore waters of Lake Ontario, with particular reference to the LOISS area. The historical water quality information is presented in three distinct, if overlapping, periods: The 1960s, the 1990s and following 2000. The area under consideration falls within the Credit Valley Conservation jurisdiction and comprises 13 watersheds that drain into Lake Ontario. These are listed in Table 1, from largest to smallest. All watersheds include a areas of storm sewersheds that either drain into the watercourses or directly into Lake Ontario. These are listed in Table 2. 1 Lake Ontario Lakewide Management Plan 2008, Chapter 1: Lake Ontario Status. Aquafor Beech Limited 3 Water Quality Report Lake Ontario Integrated Shoreline Study Table 1: LOISS Watersheds Draining into Lake Ontario Watershed Watershed area (ha) Comments Credit River 100,000 Incl. Port Credit East (97 ha) Cooksville Creek 3,529 Incl. Cawthra Creek Sheridan Creek 1,035 Applewood Creek 450 Lornewood Creek 422 Birchwood Creek 352 Tecumseh Creek 330 Incl. Port Credit West (167 ha) Turtle Creek 257 Serson Creek 235 Cumberland Creek 205 Avonhead Creek 166 Clearview Creek 134 Moore Creek