Quinte Regional October, 2004 Groundwater Study Final Report EXECUTIVE SUMMARY The Ontario Ministry of the Environment has teamed up with local municipalities, Counties and related agencies to undertake a groundwater study in the Quinte Region. The Study Area encompasses: Hastings County, Municipality of Prince Edward County, Municipality of Stone Mills in Lennox and Addington County, and the balance of the Quinte watershed. Specific emphasis was placed on the study partner municipalities of Hastings Highlands, Carlow/Mayo, Bancroft, Madoc, Tweed, City of Belleville, Tyendinaga, Prince Edward County and Stone Mills. Study Objectives The principal objective of this study was to develop an understanding of the groundwater resources in the Quinte Region. With this knowledge, management strategies are developed to protect groundwater resources, in order to maintain a safe supply of potable water for current and future generations and to protect the water resource ecosystem. To fulfill this objective, several separate but related work tasks were performed, including: i) Characterizing the regional groundwater flow systems, including areas of significant groundwater recharge and discharge; ii) Assessing the water resource capabilities of the regional aquifers; iii) Mapping areas vulnerable to groundwater contamination; iv) Compiling data relating to the existing use of the groundwater resource; v) Identifying major potential sources of groundwater contamination; and vi) Developing recommendations for groundwater management and protection strategies that can be implemented. Data generated and compiled during this study were placed into a Geographical Information System (GIS) to facilitate future manipulation and presentation of data. Study Approach The study was completed in several stages: PART 1: Understanding and Assessment of the Regional Groundwater Resource PART 2: Assessment of the Existing Use of Groundwater PART 3: Evaluation of Potential Contaminant Sources PART 4: Evaluation of Groundwater Management and Protection Measures. Dillon Consulting Limited Project No. 03-1813 Page i Quinte Regional October, 2004 Groundwater Study Final Report The results of the first three steps were used as input into the evaluation of future groundwater management and protection measures. In addition to the above, separate capture zone and well head protection area studies were performed for the municipal water supply systems in Centre Hastings (Madoc system), Municipality of Tweed (Tweed system) and Prince Edward County (Peats Point subdivision system). The results of these studies are presented in separate reports. Overall management of the Study was provided by Quinte Conservation. Direction for the study was provided by a Screening Committee (consisting of municipal representatives from the Study Area, Ontario Ministry of the Environment, Ontario Ministry of Agriculture and Food, local Health Units and Conservation Authorities) and a Technical Advisory Committee (made up of political, technical and municipal staff representatives and Quinte Conservation staff). The purpose of the Technical Advisory Committee was to provide technical input and direction to the Steering Committee and the consultants during the Study. Summary of Findings Aquifers The predominant aquifer in the Study Area is fractured bedrock. Precambrian rock is the main aquifer in Hastings Highlands, Carlow/Mayo, Bancroft, Madoc, Tweed, and the northern portion of Stone Mills. Limestone is the main aquifer in Prince Edward County, Belleville, Tyendinga, and the southern portions of Tweed and Stone Mills. Groundwater flow is through vertical and horizontal fractures within these rocks. In general, the top 10 to 30 m of the bedrock is heavily fractured and is, therefore, very susceptible to contamination. Overburden sand and gravel aquifers are present in some localized areas but are seldom used because of their limited extent and thickness. The majority of overburden aquifers that are used to supply water occur as drumlins in the former Thurlow Township, and as glacial outwash deposits in Hastings Highlands, Carlow/Mayo and Bancroft. Sand and gravel deposits in the Picton to West Lake area in Prince Edward County are also used locally as an aquifer. Groundwater Flow The direction of regional groundwater flow mimics surface water drainage patterns. In the Moira and Napanee watersheds, the regional groundwater flow is directed south to southwest. In Prince Edward County, regional groundwater flow is outwards from the plateau areas and directed to the shorelines. Beyond the Quinte watershed, in the northern municipalities of Hastings County, regional groundwater flow directions are to the northeast. Local-scale groundwater flow directions at the individual lot and concession level often deviate from deeper groundwater flow directions because of the effects of local topography. Dillon Consulting Limited Project No. 03-1813 Page ii Quinte Regional October, 2004 Groundwater Study Final Report Groundwater Recharge and Surface Water Interaction The entire Study Area can be considered a groundwater recharge area because of the predominance of fractures within the top portions of the bedrock aquifer. Precipitation that falls on the land will rapidly infiltrate these fractures and percolate to the aquifer below. On a regional scale, some areas provide deeper aquifer recharge than others. In general, areas of deep regional recharge correspond with areas that are locally elevated, such as hills and bedrock plateaus. Groundwater discharge areas occur in lowlying regions such as ravines and river valleys. Some of the surface water features identified as potentially having a significant baseflow component include portions of the Salmon River, Napanee River, Moira River, York River, and Little Mississippi River. Many of the lakes and marshes in the northern municipalities also likely have a significant discharge component. Lakes and marshes on bedrock plateaus (e.g., Lake On the Mountain, Roblin Lake) in Prince Edward County may act as local aquifer recharge areas. Aquifer Vulnerability The majority of the Study Area has been mapped as highly vulnerable. Isolated occurrences of clay are present in some localities, but rarely attain thicknesses that would allow for significant protection of the underlying bedrock aquifer. The high vulnerability of the aquifer makes the entire Study Area susceptible to contamination. A few very small areas were identified as moderately vulnerable in the municipalities of Tweed, Madoc, Hastings Highlands and Carlow Mayo. These wells intercepted clay, silt or till layers that were of sufficient thickness to be deemed as providing some aquifer protection at the local scale. Well Yields Most wells provide sufficient volumes for residential use on private services (approximately 13 L/m or 3 igpm); however, the risk of drilling a low yielding well varies across the Study Area. Average pumping rates are generally higher in the southern municipalities in sedimentary aquifers (with the exception of Prince Edward County) than in the northern municipalities where the aquifer is Precambrian rock. Poor yielding wells (<1 igpm) are most common in Hastings Highland, Carlow/Mayo, Bancroft and Prince Edward County. The probability of drilling a well with an acceptable yield depends upon the amount of fractures intercepted by the well. Considering that these fracture patterns are irregular, it is difficult to predict an area of good water quantity. Natural Water Quality The natural water quality is generally good. Sulphur problems are restricted mainly to the limestone aquifer, and are greatest in areas that receive water from the shaley Verulam Formation. Areas prone to sulphur water problems include Prince Edward County, Tyendinga and Belleville. The risk of encountering salty water increases with well depth beyond 30 m. The least water quality problems are reported in the Dillon Consulting Limited Project No. 03-1813 Page iii Quinte Regional October, 2004 Groundwater Study Final Report municipalities that pump primarily from the Precambrian rock aquifer, such as Hastings Highlands, Bancroft, Carlow/Mayo, Madoc and the northern portions of Tweed and Stone Mills. Groundwater Use Within the Study Area, groundwater is a major source of water for domestic, commercial, and agricultural activities. The estimated groundwater use over the nine study partner municipalities participating in the Regional Study is approximately 5,400,000 m3/year. The largest groundwater use is for potable water supply from individual private wells. Approximately 45,800 people (46% of the Study Area’s population) rely on groundwater for their potable water supply. Groundwater users, by percentage of total population, are: Stone Mills (100%) Carlow/Mayo (100%) Tyendinaga (100%) Prince Edward County (59%) Tweed (100%) Town of Bancroft (38%) Madoc (100%) Belleville (13%) Hastings Highlands (100%) There is no indication of regional depletion of the aquifers as a result of over pumping. Localized areas of aquifer mining or interference caused by over withdrawal likely occur; however, these situations are localized and do not reflect widespread problems. Since the bedrock aquifer is sensitive to precipitation events, water levels are prone to drop during periods of drought. Contaminant Inventory An inventory of known and potential contamination sources was developed. Where possible, geographic coordinates were assigned to each known or potential source. A detailed methodology was developed and documented