Groundwater studies in Ontario Mapping a hidden treasure C O N T E N T S 4 PROTECTING THE GROUNDWATER RESOURCE 6 GROUNDWATER BASICS 8 REGIONAL AQUIFER CHARACTERIZATION Defining Local Groundwater Conditions 10 MANAGING A PUBLIC GROUNDWATER SUPPLY Wellhead Protection Area Identification 12 PINPOINTING POTENTIAL POLLUTION PROBLEMS The Contaminant Source Inventory 13 UNDERSTANDING THE DEMANDS Groundwater Use Assessment 14 PUTTING TOGETHER AN ACTION PLAN What Can Communities Do To Safeguard Groundwater? 16 A GLOSSARY of Common Groundwater Terms ~ G R O U N D W A T E R S T U D I E S I N O N T A R I O ~ MAPPING A HIDDEN TREASURE Detailed scientific studies, conducted at the local level and supported by the Ministry of the Environment, are being used to better understand and, ultimately, safeguard one of Ontario’s greatest “buried treasures”: our groundwater resources. For some three million Ontarians, groundwater As part of a province-wide initiative, community- is the primary source of the water used in their led groundwater studies are being undertaken to homes and farms, businesses and industries. promote groundwater source protection in They depend on the groundwater resource to Ontario. This cooperative initiative — involving keep their schools, hospitals, fire services and municipalities and conservation authorities, other institutions operating. Ninety percent of together with residents, farmers, business leaders Ontario’s rural residents rely on wells for their and other stakeholders — is providing local water supply. decision-makers and water managers with the solid scientific information needed to safeguard groundwater sources. Understanding the groundwater resources of a community means methodically studying groundwater conditions, defining wellhead protection zones and other sensitive areas, cataloguing the potential threats to water quality, and tracking groundwater usage patterns. These studies comprise the necessary first steps in developing an effective groundwater source protection strategy. This publication describes the groundwater research being conducted by municipalities and conservation authorities across the province, and how this information is being used to ensure that the groundwater resource remains clean and plentiful for generations to come. Protecting the Groundwater Resource In Ontario, some three million residents — • Contaminant Inventories catalogue the potential living in more than 200 communities, and on the threats to groundwater quality. Unless stored, surrounding farms and rural homes — depend handled and used correctly, toxic chemicals and on an abundant and clean supply of groundwater. fuels, manure and fertilizers, pesticides and road The protection of this vital resource requires salt can enter the groundwater environment and reliable and up-to-date scientific knowledge pose a threat to public health and safety. of the groundwater resource and the threats • Water Use Assessments reveal the demands to that resource. Since 1998, the Ministry of the on the groundwater resource to meet the needs Environment has helped fund up to 85 percent of residents, farmers, business and industry, of the cost of these essential groundwater schools, hospitals and other local institutions. studies across the province. Studies conducted by municipalities, regional governments and Groundwater protection is a partnership initiative. conservation authorities are supplying much of The province is working with municipalities, the critical information these communities need regional governments, conservation authorities, to effectively manage their groundwater resource. and other stakeholders to conserve and protect the resource. Collaborative steering committees Studies are being completed in over 95 percent that are designing, overseeing and conducting of the groundwater-dependent communities in the groundwater studies are also providing a solid Ontario, providing those communities with a much management structure for implementing future better understanding of the groundwater supply, source protection measures. the threats to its future quality, and the issues that should be addressed as part of an integrated source The study process is an excellent forum for protection strategy. educating communities about the value of groundwater and the steps necessary to conserve The studies include four basic components: aquifer and protect it. Programs that draw local and characterization, municipal wellhead protection regional stakeholders together have proven the area mapping, contaminant inventories, and water value of focusing attention on source protection. use assessments. The information produced through the groundwater • Aquifer Characterization shows us, at a regional studies is helping private, public and non- scale, where groundwater is distributed, where government sectors make informed policy it is replenished, and where it is discharged to decisions and ensure Ontario’s groundwater rivers, streams and lakes. This work also includes remains plentiful and clean. mapping areas of intrinsic susceptibility, where pollutants released onto the land’s surface could more easily seep down to the groundwater below. • Wellhead Protection Area studies analyze the local geology and groundwater conditions surrounding a community well and then define a series of protection zones based on the length of time it would take a contaminant dissolved in the groundwater to reach the well. Research methods and data standards Gathering information on local for groundwater studies. conditions is the first step in protecting groundwater. In November 2001, the Ministry of the Environment published technical Terms of Reference for While the province has contributed funding groundwater studies being funded by the province. and technical guidance, groundwater studies are This detailed document sets minimum research the responsibility of local or regional steering standards and data collection requirements. The committees of decision-makers, conservation Terms of Reference describe the methodology for authorities and other stakeholders. Here are the studying groundwater conditions and defining aquifer basic steps that committees are taking to develop susceptibility, completing a contaminant source the source protection strategy that makes sense inventory, conducting a groundwater use assessment, for their community. and mapping wellhead protection areas. As each funded study has to submit final reports and data Form a community steering committee or to the Ministry, the Terms of Reference also set basic planning team that represents local interests, reporting requirements and minimum data standards 1 major water users and other key stakeholders, to ensure consistency across different study areas. environmental expertise, and residents and non-governmental groups. Groundwater systems do not conform to Collect up-to-date and reliable information municipal boundaries. It’s important for on groundwater resources. Characterize municipalities, conservation authorities the regional aquifers and their intrinsic and other stakeholders to work together — 2 susceptibility to contamination, identify at all stages in the source protection municipal wellhead protection areas, and process — to protect groundwater on assess current groundwater use. a regional or watershed basis. Identify any potential threats to the resource, such as underground storage tanks, active and 3 closed waste disposal sites, PCB storage sites and abandoned wells. In most cases, a local steering committee is given the job of overseeing the technical aspects and public consultation Put together an action plan that meets components of each groundwater study. the specific needs of the study community, Typically, the steering committee includes including an overall or guiding strategy, a list technical experts, municipal staff and of regulatory and non-regulatory measures 4 that might be implemented, monitoring needs, consultants, as well as residents, farmers, and the outreach and education programs to business people and other stakeholders. promote public awareness of groundwater issues and protection opportunities. Groundwater Basics The precipitation that falls to earth can travel by a number of pathways on its journey through the hydrologic cycle. Much of the water either evaporates or is transpired through plants back into the atmosphere. Some flows overland through Ontario’s network of rivers, lakes and wetlands. And a small portion of that water seeps downward through the spaces between soil particles and cracks in the bedrock where it collects in underground aquifers. In turn, these layers of sediment, sand and gravel saturated with Understanding the demands groundwater feed our private and municipal wells. for groundwater The surface area of land where water infiltrates Groundwater does more than supply water for into the ground down to the water table is called human needs; it also maintains the baseflow in the recharge area. The accumulated groundwater streams and rivers and supports the natural feeds the wells that serve local farms, residents and ecosystem. It is important to assess the current businesses. It also supplies the springs, streams and and future pressures on the aquifer in order to marshes that support the aquatic ecosystem, and implement any needed conservation measures and provides moisture to trees and other deep-rooted sustain the ecological functioning of the watershed. vegetation during dry periods. A sustainable groundwater supply is inseparable from a sustainable community. Local planners and water managers need certain information in order to make balanced decisions that will protect their community’s livelihood and the resource they depend on. Groundwater studies help communities better understand who withdraws water and in what volume, how groundwater gets replenished, and how quickly the aquifer recharges. Some examples of entities that withdraw groundwater include: • Public and private water suppliers for residential, commercial, industrial, institutional and public use; • Individual users not connected to a municipal system, that can include residential wells, large and small businesses, schools, hospitals, golf courses, pools and others; and, • Agricultural operations for watering livestock and irrigating crops. R E AT W BLE A T What’s an aquifer? An aquifer is a geological formation, such as porous sand and gravel or fractured rock that is able to supply a useable The way that water — as quantity of water. well as any contaminants it may contain — moves through the ground and into an aquifer depends on a number of characteristics, including the porosity, the permeability and the geological structure of the area. Regional Aquifer Characterization: Defining Local Groundwater Conditions ARegional Aquifer Characterization maps the basic groundwater conditions across a study area. It identifies where the groundwater resource is replenished, where it is distributed and stored, and where it is discharged to lakes, rivers and streams. This component of the study requires a variety of information from a number of sources. Water well data from the provincial database, municipal records and independent reports provide a wealth of geological and hydrological information. Details on surface water features, land use, surface and bedrock geology, and surface topography are also key ingredients for defining groundwater conditions. Some studies are supplementing existing information sources with additional field work, including constructing and analyzing new boreholes, pump testing existing wells, and sampling stream flow. Mapping Groundwater Susceptibility From these sources, topographical, geological As part of the regional aquifer characterization, maps and hydrological data is collected, compared and are generated that show where groundwater may be more consolidated, validated as necessary, standardized, susceptible to any pollutants released on the ground surface. interpreted and mapped. The maps produced from Areas of high, medium and low intrinsic susceptibility are this information and analysis illustrate some of identified, depending on the depth to the water table and the key characteristics and functions of the local how readily the overlying rock and soil could retard the groundwater system, including the water table, downward migration of contaminants. For example, an flow directions, recharge areas, and discharge areas. aquifer with 20 metres of clay or silt situated above it would Groundwater can be degraded by a variety of contaminants • The bacteria and viruses found in sewage sludge, septic tanks and manure are readily absorbed on to clay particles or filtered out in sand. Most die off and are decomposed in about 100 to 250 days. However, they can also be carried a considerable distance through coarse gravel or fractured bedrock in this time period. • Nitrates from fertilizers and organic waste are highly soluble, stable and capable of migrating considerable distances if they are leached into INTRINSIC SUSCEPTIBILITY a groundwater source. INDEX HIGH (ISI Score < 30) • The chloride in road salt is highly soluble and MEDIUM (ISI Score 30–80) can readily build up in an aquifer. LOW (ISI Score > 80) • Gasoline, fuel oil and other petroleum products can be harmful in drinking water at only a few parts per billion. While petroleum products seldom travel more than several hundred metres from their source, they can persist in the environment for years. • Highly toxic chlorinated solvents, such as paint removers, dry cleaning fluids and metal degreasers, are also very persistent and can be highly mobile in groundwater. Heavier than water, they tend to pool at the bottom of an aquifer and can be very difficult to detect or remove. • While many of the pesticides in use today are biodegradable, they can be toxic at low concentrations. Some of their breakdown products are also dangerous. have a low intrinsic susceptibility, while one with 10 metres of coarse gravel above would be much more susceptible to contamination. Groundwater susceptibility mapping can be Virtually anything spilled or placed on the ground used to help guide planning and management decisions to can potentially leach into groundwater. Compounds better protect the future of the groundwater resource. These that are persistent, don’t readily degrade, are maps provide valuable information for regional-scale soluble in groundwater, or are toxic in very small analyses of intrinsic susceptibility. A re-assessment that doses pose the greatest threat to groundwater includes other local-scale information may be required to quality and, subsequently, to human health. verify the degree of susceptibility at any specific location. Managing a Public Groundwater Supply: Wellhead Protection Area Identification Wellhead protection areas are being delineated for municipal wells or wellfields in the study areas. The wellhead protection area identifies the sub-surface area that supplies groundwater to the well. The protection area is comprised of time-of-travel capture zones that are based on the direction and speed of groundwater flow to the well. These zones represent the horizontal distances that water (and any contaminants it carries) is likely to travel through the aquifer towards the well over set periods of time. The time-of-travel zones are mapped using sophisticated computer models, taking into consideration pumping rates and local groundwater conditions. In most cases, three-dimensional computer models are used to delineate capture zones and produce realistic time-of-travel boundaries. In certain situations, other mathematical formulae may be more appropriate, like the uniform ZO N E flow method or the calculated fixed radius method. 2 Z O N Different contaminants behave differently in the ground- E 1 water environment. Some break down rather quickly or readily adhere to soil particles, while others dissolve in the water or are highly mobile and persistent. Because of this, a minimum of three different zones are being identified. *Please Note: These definitions have been used for study purposes only and do not constitute a legal defi For many communities across the province, groundwater is not just the primary source of water. It is their only source. It is safer, more efficient and economical to prevent groundwater problems than to try to clean up a contaminated aquifer or replace a degraded water supply.