NOTICE TO READER Water Quality and Management of Lake Trout Lakes County of Lennox and Addington: 2005 ii April 2011 Water Quality and Management of Lake Trout Lakes County of Lennox and Addington: 2005 For more information: call toll free 1-800-565-4923, Toronto area call 416-325-4000 [email protected] Ontario.ca/Environment PIBS 6828e ISSN/ISBN 978-1-4249-9629-2 © 2011, Queen’s Printer for Ontario iii Notice to Reader This information is being provided to you as a reference for water quality in lake trout lakes in the County of Lennox and Addington and to assist with future planning decisions on lake trout lakes in the County of Lennox and Addington. The findings, conclusions and recommendations of the Ministry of the Environment (the Ministry) set out in this report are based in part, on information provided by others. The information that has been provided by others and which is relied upon by the Ministry is understood to be factual and correct; however the Ministry cannot guarantee that the information that has been provided by others is accurate or complete. The findings, conclusions and recommendations of the Ministry of the Environment (the Ministry) set out in this report are based, at least in part, on information collected from recent sampling conducted by Ministry staff. The sampling was conducted in accordance with approved Ministry guidelines and methods for field operations. Water quality samples were analyzed by the Ministry of the Environment’s Laboratory Services Branch in Toronto according to accredited methodologies. Temperature and dissolved oxygen profiles were recorded after calibration of the instruments according to the manufacturer’s manual. Ongoing sampling surveys will be conducted in the future by Ministry staff to evaluate changes in water quality of lake trout lakes in the County of Lennox and Addington. Although the Ministry endeavours to ensure that the information contained in the summary of the data is as accurate as possible, errors may occasionally occur. Avertissement: Cette publication hautement spécialisée Water Quality and Management of Lake Trout Lakes; County of Peterborough : 2004 and 2010 n'est disponible qu'en anglais conformément au Règlement 671/92, selon lequel il n’est pas obligatoire de la traduire en vertu de la Loi sur les services en français. Pour obtenir des renseignements en français, veuillez communiquer avec le ministère de l’Environnement au 613-549-4000. iv Table of Contents Introduction ...................................................................................................................................1 Sources of Phosphorus ..................................................................................................................3 Effects of Phosphorus....................................................................................................................4 Lake Trophic Classification .........................................................................................................4 Lake Processes................................................................................................................................5 Physical Changes.................................................................................................................5 Biological Changes..............................................................................................................6 Chemical Changes...............................................................................................................6 Description of Study Lakes...........................................................................................................7 Sampling Methods.........................................................................................................................8 Water Quality and Lake Trout Habitat.......................................................................................9 Dissolved Oxygen................................................................................................................9 Phosphorus.........................................................................................................................11 Nitrogen.............................................................................................................................11 Carbon................................................................................................................................11 Acidity and Alkalinity........................................................................................................12 Conductivity.......................................................................................................................13 Lake Capacity Assessment..........................................................................................................16 Land Use Planning.......................................................................................................................17 Recommendations........................................................................................................................18 Lakes deemed to be At-capacity........................................................................................19 Lakes deemed to have additional capacity.........................................................................19 Recommendations Applicable to all Lakes........................................................................19 Glossary of Terms........................................................................................................................21 Lake Data Appendices.................................................................................................................25 List of Tables Table 1. Lake Trophic Classification.....................................................................................5 Table 2. Morphometric Features of Lennox and Addington County Lake Trout Lakes.......8 Table 3. Volume-weighted Mean Hypolimnetic Dissolved Oxygen for County of Lennox and Addington Lake Trout Lakes, 2004...............................................10 Table 4. Summary Chemistry Data for Euphotic Zone (Surface) for County of Lennox and Addington Study Lakes..........................................................................................13 List of Figures Figure 1. Map of the County of Lennox and Addington.........................................................2 Figure 2. Thermal Stratification of Lakes ..............................................................................5 v List of Lake Appendices Ashby Lake....................................................................................................................................26 Buckshot Lake ..............................................................................................................................32 Effingham Lake ............................................................................................................................36 Lower Mallory Lake .....................................................................................................................40 Mazinaw Lake ...............................................................................................................................45 Otter Lake ................................................................................................................................50 Trout Lake ................................................................................................................................56 Weslemkoon Lake ........................................................................................................................62 vi Introduction other fish species. Lake trout require clean, clear, deep lakes with well-oxygenated Inland lakes constitute a major bottom waters. Although lake trout are environmental, recreational and economic present in only 1% of Ontario’s lakes, these resource for the province of Ontario. In lakes make up 25% of the world’s lake trout 1990 anglers spent an estimated 2.5 billion resource2. Lake trout lakes, more than any dollars in purchases and activities related to others, epitomize the ideal of pristine, clear, fishing in Ontario’s inland lakes.1 Increased quintessential wilderness waters. demand for waterfront property and the proximity of lakes in southern Ontario to Lake trout lakes are an important part of our major urban centers has resulted in natural heritage and provide high quality considerable residential and commercial angling and recreational experiences. In a development on many of our lakes. significant number of Ontario lakes, lake trout populations have been lost or are Lakes have a finite capacity to accommodate severely impaired. Unless properly most types of development. One of the managed, these fisheries and their benefits primary concerns over shoreline will be lost forever. development is its impact to water quality. Land use changes around a lake can have a detrimental effect on water quality. Continuing pressure to develop shorelines requires that periodic water quality assessments be undertaken to assist in planning decisions regarding lake development. The County of Lennox and Addington (Fig. The primary linkage between water quality 1) is an upper tier municipality and is and shoreline development is nutrient input responsible for the preparation of an Official to the lake. Development can increase the Plan (OP). The Planning Act requires a supply and availability of “fertilizing” plant municipality to have regard to the Provincial nutrients such as phosphorus and nitrogen. Policy Statement (PPS). The Provincial These nutrients promote the growth of algae Policy Statement outlines matters of and other aquatic plants. As the provincial interest in land use planning. The proliferating algae die off they settle to the PPS requires that development be permitted lake bottom and decompose. The only if there will be no negative impact on decomposition process consumes oxygen, natural heritage features such as fish habitat which reduces the amount of dissolved and water quality. oxygen (DO) in the bottom waters of the lake. This bottom layer is often referred to 1. MOE, 1997. Economic analysis of the proposed Lakeshore Development policy: Social-economic value of water in Ontario. as the hypolimnion. Economic Services Branch, Ministry of the Environment. Development can be especially detrimental 2. MOE, MNR & MMAH... 2003. Lakeshore Capacity Assessment Handbook: Protecting Water Quality in Inland Lakes on Ontario’s to lake trout lakes. Habitat requirements for Precambrian Shield. Draft Report. February, 2003. lake trout are more demanding than those of 1 Figure 1. Map of the County of Lennox and Addington. 2 In order to assist the County in developing sewage disposal servicing shoreline land use policies pertaining to shoreline development is the septic tank leaching bed development, the Eastern Region of the system. A leaching bed provides for an Ministry of the Environment undertook a underground release of sewage effluent into water quality assessment of lake trout lakes the soil. Phosphorus and nitrogen from the in County of Lennox and Addington during effluent can migrate through the ground and 2005. impact water resources. Although some of the phosphorus and nitrogen from the The Ministry of Natural Resources (MNR) sewage effluent is adsorbed by the soil or identified 8 lakes in County of Lennox and taken up by vegetation, over the long-term Addington that are being currently managed these nutrients may be released to the lake. by the MNR as a lake trout fishery. This report documents the water quality of these Sewage is not the only source of phosphorus lake trout lakes. arising from shoreline development activities. Land use changes in the immediate vicinity of a lake can result in Sources of Phosphorus additional phosphorus inputs. Disturbance of the natural shoreline through the clearing In lakes on the Canadian Shield, phosphorus of trees and undergrowth and the addition of is the most essential nutrient for the growth lawns, driveways and other landscape of algae and aquatic plants. It is found features decrease the permeability of the naturally in all aquatic ecosystems. Lakes ground. receive phosphorus from surface runoff from their surrounding land area; from This “ground hardening” reduces infiltration tributary inflows from upstream lakes and of water resulting in increased surface runoff wetlands; from atmospheric deposition to the lake. directly on the lake surface and from the bottom sediments of a lake which can The application of fertilizers to lawns and resolubilize phosphorus under anoxic (no gardens and increased soil erosion caused by oxygen) conditions. the disturbance of the natural shoreline introduce additional sources of phosphorus Surface runoff from across the watershed to the lake. can pick up particles of soil and vegetation containing phosphorus. This surface runoff drains into lakes and their tributary streams. The phosphorus in atmospheric deposition includes dust, pollen and other wind borne particulates from bare agricultural fields and unpaved roads. Human activities in the vicinity of a lake introduce a supply of phosphorus, sometimes referred to as the artificial or anthropogenic load. Domestic sewage contains high levels of phosphorus and nitrogen. The most common form of 3 Effects of Phosphorus water clarity. Algae and other organic matter eventually settle to the bottom of the Unlike other aquatic pollutants, phosphorus lake where they decompose through is not directly toxic to aquatic life. High bacterial action. This decomposition levels of phosphorus, however, can set off a process utilizes oxygen. sequence of events that can have serious impacts on the quality of recreational waters Cold water salmonid species of fish, such as and their fisheries. lake trout, require cold, well-oxygenated water found at the bottom of deep lakes and Phosphorus, more than any other nutrient, are sensitive to oxygen depletion which promotes the growth of algae and larger occurs in the deeper bottom waters. aquatic plants (macrophytes). Because Reduced levels of oxygen in deeper waters phosphorus in freshwater ecosystems is the force these species to migrate into nutrient in shortest supply, small additions shallower, warmer, well oxygenated water. of phosphorus can result in accelerated These conditions increase the stress levels growth and increased abundance of algae on lake trout and expose juvenile lake trout and macrophytes. to predation. Algae are single celled, mostly microscopic, Lake Trophic Classification green plants. A certain amount of algae and aquatic plants are essential for the proper One common method of classifying lakes is functioning of a healthy lake ecosystem. on a continuously rising trophic (nutrient They provide food and shelter to fish and enrichment) scale according to their through the process of photosynthesis biological productivity. This classification release oxygen to the water column. system is normally related to the nutrient Generally, an increase in the production of concentration levels in a lake system, its algae gives rise to an increase in growth at water clarity and its algal biomass. all levels of the food chain up to and including fish. This causes changes in Lakes with relatively little nutrient input and species composition and reduces levels of low productivity are referred to as oxygen in the bottom waters of deeper lakes. oligotrophic. Oligotrophic lakes are The increase in biological productivity of a characterized by low levels of algae, lake in response to nutrient enrichment is exceptionally clear water, low species referred to as eutrophication. diversity and a well-oxygenated hypolimnion (deep bottom waters that While a certain amount of nutrient remain cold throughout the summer). These enrichment is beneficial, run-away types of lakes provide conditions that are eutrophication can bring about a loss in the suitable for salmonid species such as lake recreational value of a body of water and trout. degrade the structure of the biological community. Excessive growth of rooted At the other end of the spectrum are the aquatic plants can blanket the shallow eutrophic (enriched) lakes. These lakes are regions and interfere with swimming and rich in nutrients and highly productive. boating, while increased concentrations of Eutrophic lakes are generally characterized algae in the water can result in decreased by dense populations of aquatic plants and 4