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LAKEHEAD REGION
GROUNDWATER MANAGEMENT AND PROTECTION STUDY

Executive Summary

Introduction

The Lakehead Region Conservation Authority, in partnership with the Incorporated areas of the City of Thunder Bay; Municipality of Oliver Paipoonge; Municipality of Neebing; Township of Shuniah; Township of Conmee; Township of Dorion; Township of O’Connor; Township of Gillies; and parts of the Unincorporated Areas of Devon, Fraleigh, Lybster, Marks, Adrian, Horne, Dawson Road lots, Forbes, Fowler, Ware, Jacques, Gorham, and Sibley undertook this groundwater management and protection study with partial funding assistance from the Ministry of the Environment (MOE). This is one of a number of groundwater studies that were funded by the MOE in the Province of Ontario in 2003.

R. J. Burnside and Associates Ltd. (Burnside) in partnership with AMEC Earth and
Environmental Limited (AMEC) was retained to conduct this groundwater study based on the terms of reference developed for the project and with specific reference to the Technical Terms of Reference (TTOR) for Groundwater Studies developed by the MOE (November 2001). All study components have been completed in accordance with the MOE funding agreement.

The main objectives of the MOE funded groundwater studies were to:

• Obtain a better understanding of the groundwater resources within the study area, 
• Complete a hydrogeological characterization and mapping of the area, 
• Complete an inventory and assess potential contaminant sources, 
• Assess water use in the area, 
• Assess groundwater vulnerability, and
• Assist in the development of groundwater protection strategies. 

Figure 1.1 presents the study area showing the municipal boundaries and principal features within the area. The study area extends approximately from Whitefish Lake in the west to the head of Black Bay in the east, and from Lake Superior in the south, to Dog Lake in the north.

The study area was defined in consultation with the municipalities within the study area.
Figure 1 shows the study area with principal topographic features. The results of the study are briefly summarized in the following sections.

Hydrogeologic Characterization
Surficial deposits within the study area are of Late Wisconsinan age, deposited by the retreating ice margin around 12,500 years ago. A re-advance approximately 11,500 years ago by the Superior Lobe incorporated some lacustrine sediments, deposited between the glacial advances into subsequent till units.

Overall, surficial deposits are thin throughout the area, with local exceptions. North of the Kaministikwia River, all watercourses contain bedrock cuts, indicative of thin cover. The maximum overburden thickness within the study area is near the mouth of the Kaministikwia River, where wells show the combination of glacial deposits and lacustrine sediments to be up to 50 m (160 ft) thick. Moderately thick outwash gravels to the north of the City of Thunder Bay can reach a thickness of 12 m (40 ft), but depths of 3 to 5 m (10 to 16 ft) are more common. Units of glacial till within the study area are relatively thin, usually less than 14 m (46 ft) in thickness.

A number of overburden types occur throughout the area. A large area of till occurs west of the City of Thunder Bay and north of the Kaministikwia River, and is subdivided into stoney sand till, clay till and silt till units. The tills typically contain a significant proportion of fine-grained material.

Additional fine-grained material was deposited in glacial meltwater lakes, ponded behind the Superior ice lobe, and flooded the area to an elevation of at least 260 m (850 ft) above sea level (asl) (75 m above present Lake Superior elevation of 185 m asl). Lacustrine deposits from earlier intervals of glacial retreat occurring at elevations to 366 m (1200 ft) are also noted in logs of water wells northwest of Kakabeka Falls.

Bedrock Geology
Understanding of the bedrock geology is a key component to understanding deeper aquifer distribution and groundwater movement within the study area. The geological description of the bedrock units in the study area is intended to identify regional aquifers for the purpose of assessing the groundwater resource and protection. Information on the bedrock geology was compiled from numerous sources, including: Ontario Geological Survey mapping, geological reports on Paleozoic geology from various authors, a review of well records, etc. The majority of the study area is underlain by Precambrian rocks as illustrated in Figure 4.1.

Bedrock of the Thunder Bay area consists entirely of rocks of Precambrian age, in excess of 2.5 Ga (billion years) in age (Ontario Geological Survey Report GR164, 1977). These rocks have been extensively deformed through metamorphism, with erosional and intrusional contacts further complicating the local geology. In general, the oldest rocks are metavolcanics, overlain by metasediments with this sequence locally intruded by smaller ultramafic and felsic units.

A younger sequence of rocks overlies these, and consists mainly of sedimentary rocks of the Animikie Series, which is comprised of the Gunflint and Rove Formations. These formations are made up of a complex variety of rock types, ranging from cherts to conglomerates, with interbedded argillites and carbonates.

Overburden in the Thunder Bay study area is highly variable in thickness and composition. Thick units of relatively coarse-grained material such as sand and gravel are best for hosting good groundwater aquifers in overburden material. Such areas include glaciolacustrine beach gravels, areas of glaciolacustrine sands, and bedrock depressions filled with thicker units of overburden. The nature of the bedrock underlying an overburden aquifer can also influence the quality and quantity of the water resource. Given the variable nature of the surficial material in the study area, and the variability of the bedrock material itself, delineation of aquifer suitability in terms of water supply potential and water quality, would require site-specific hydrogeological studies.

Regional groundwater flow is generally from the higher elevation areas in the northern part of the study area, southwards, toward Lake Superior. Local groundwater flow parallelssurface topography, particularly adjacent to major river valleys. Regional recharge occurs mainly where thick units of coarse sand and gravel are exposed and from bedrock topographic highs. Groundwater recharge occurs through direct infiltration of precipitation, and recharge from surface streams and wetlands.

Groundwater Modelling
The application of a 3-D groundwater model was utilized to delineate municipal well capture zones. The two municipal wells in Rosslyn Village were assessed using the 3-D numerical model known as MODFLOW.

The top and bottom elevations of the overburden and bedrock aquifers were delineated from the detailed cross-sectional analysis of the hydrostratigraphy. Boundary conditions
represented in the models include: vertical recharge through the upper layer of the model, rivers and lakes at the ground surface, etc. Overburden hydraulic conductivity was estimated at each interpreted borehole by assigning local and literature hydraulic conductivity values to the observed lithologies. Pumping wells were assigned to the grid cells nearest to the well location coordinates.

Capture zone delineation was completed using the model parameters outlined above for 50 days, 2 year, 5 year, 10 year, and 25 year time periods.

Water Use and Water Quality
Present water use within the categories of domestic, municipal, public, commercial/industrial and agricultural uses were reviewed in terms of amount and adequacy of water. In order to ensure sustainable growth, the rate of groundwater extraction must be related to groundwater recharge and the maintenance of satisfactory baseflow in local streams. The water use and water budget assessments indicate that there is potential for future groundwater development in the area.

Groundwater quality data for the municipal wells was reviewed. Water quality was
determined to be good, with general water quality in most wells being characterized as
calcium carbonate and bicarbonate water. Local variations in subsurface stratigraphy and
land uses have resulted in mixed waters in some wells. In general, water quality is consistent with that determined in previous years.

Aquifer Vulnerability to Contamination
An aquifer vulnerability assessment was undertaken through the evaluation of intrinsic susceptibility assessment following the TTOR (MOE, November 2001) The potential vulnerability of an aquifer to groundwater contamination is a function of the susceptibility of its recharge area to infiltration. The results of this assessment indicate that the majority of the study area is defined as either moderately or highly vulnerable to groundwater contamination. This is due to the relatively thin to non-existent overburden above the bedrock and the proximity of the water table to ground surface. This combination of physical features tends to make large portions of the study area susceptible to groundwater contamination.

Groundwater Management and Protection Plan
The groundwater management and protection plan developed for the municipal wells in the study area involved a review of the groundwater management strategies that could be
adopted by the communities and evaluation of; land use risk rating, identification of protection measures for the recharge area and reviewing various components of a wellhead protection plan. Subsequently, the municipal well capture zones and the intrinsic susceptibility mapping were merged to produce a land use risk rating for the land areas near the municipal wells.

The land use risks have been classified as high for all the area within a 2-year capture zone and moderate to low within the 10 to 25 year capture zones depending upon local intrinsic susceptibility. The existing potential sources of contamination have also been plotted on these figures. Based on this analysis, the need for assessing and monitoring some of the contaminant source areas has been identified.

The land use risk-rating addresses only the groundwater sources tapped presently by the
municipal wells. The capture zone analysis is based on current water takings and is not based on a watershed approach. In order to protect the groundwater resources in the area, the recharge area has to be protected. It should be noted that the intrinsic susceptibility over most of the area was found to be high to moderate, thus, necessitating protection measures.

A brief summary of various options available to each community to develop a groundwater management and protection plan that could be incorporated into their Official Plan is also provided in the report. Examples of some wellhead protection plans developed by various agencies in Canada and USA were also reviewed and copies of the same are included in the report.

As a part of the groundwater management action plan, a groundwater-monitoring program has been proposed. This monitoring program may be given due consideration by the MOE to augment the Provincial Groundwater Monitoring Network.

Emergency response plans and a review of policies and regulations has also been included as part of the groundwater management and protection plan. An implementation plan identifying roles and responsibilities of various municipal departments and other agencies, along with possible funding sources has also been discussed in the report.

Conclusions

The conclusions and recommendations drawn in the study are briefly summarized below:
Based on the detailed hydrogeological characterization, aquifer delineation, municipal well capture zone analysis, aquifer intrinsic susceptibility assessment, contaminant sources inventory, and analysis of land use risk rating, the following conclusions have been drawn:

1. Precambrian metavolcanics and metasedimentary rocks underlie the majority of the area, and are intruded by felsic to mafic rocks of various compositions. The generalized stratigraphy present in the study area consists of seven major overburden types and five bedrock types.

2. The intrinsic susceptibility mapping indicated that most of the area is covered with a thin overburden or exposed bedrock, where the water table is expected to be shallow and the aquifer is susceptible for contamination. The high to moderate sensitivity area also includes the area covered by surficial sand and gravel deposits, which are identified as “recharge areas”.

3. Time related capture zones for the Roslynn Village wells were delineated using a 3-D groundwater modelling techniques and indicate that the principal recharge areas for the wells are as shown on the respective maps.

4. The potential sources of contamination inventory identified a number of potential contaminant sources, mainly concentrated within the City of Thunder Bay core and urbanized areas along major transportation corridors.

5. Land use risk rating analysis identified that the areas within 2-year time of travel (TOT) capture zones are vulnerable and the areas within 10 to 25 year TOT were identified as moderately risky.

6. Given the size of the study area and the population distribution, data gaps are inevitable. This study is the first of its kind in the area and represents an amalgamation of a number of data sources from existing databases.

Recommendations

The following recommendations have been provided:

1. The Rosslyn Village WHPA delineations should be included in the Municipality of Oliver-Paipoonge Official Plan, such that certain land use/activities are restricted within groundwater capture zones as per land use risk rating. Effective land use policies are essential to ensure that future development does not reduce groundwater recharge, deteriorate groundwater quality or deplete groundwater resources.

2. The Municipality of Oliver-Paipoonge should install upgradient groundwater quality monitoring wells for the Rosslyn municipal wellfield. This will permit the municipality to assess groundwater quality of groundwater moving towards the municipal wellfield.

3. A staff member from LRCA should be identified to coordinate and implement future groundwater protection/management programs and initiatives (community awareness and public education, etc.).

4. Due to the number of private wells and septic systems in the study area, the goals and objectives that embody wellhead and groundwater protection must be communicated to the citizens in the study area. Individuals must realize that they have an important role to play in ensuring that their well and septic system is in compliance with all relevant regulations. This can only be accomplished through the delivery of a comprehensive community awareness/education campaign. The LRCA should take the lead to assemble a task force of partners with local representation, and proceed with the implementation of such a program.

5. The groundwater management and protection plan included in this report can serve as a basis for identifying and developing appropriate groundwater protection strategies for each community and/or municipality.

6. Local municipalities and Townships should agree on a process whereby new hydrogeological data (or other relevant information), which becomes available through detailed site investigations (or similar studies) can be incorporated into this study. Updates/revisions to the mapping should be carried out on a periodic basis. This will allow the information compiled in this study to become a “living document” as new information becomes available. The partner municipalities, LRCA and the MOE need to ensure that there is a clearly defined “guardian” of the data, who is prepared and capable of ensuring that the data are kept up to date.

7. Some suggested approaches and Best Management Practices (BMP) have been included in this report and should be further explored and implemented, particularly in those areas where groundwater is susceptible to surface sources of contamination.

8. A long-term groundwater-monitoring program should be developed in the study area to resolve data gaps noted in this study. The program should be developed in consultation with all area Townships and Municipalities and the LRCA, who are coordinating new monitoring well installations as part of the Provincial Groundwater Monitoring Network. The groundwater-monitoring program should be designed to address:

• Water quality and quantity concerns in the communities experiencing development pressure (e.g. Kakabeka, Rosslyn Village, Murillo);
• Water quality concerns in the Slate River Valley; and
• Potential impacts associated with road salting activities throughout the study area.

9. It should be noted that this groundwater study is completed on a regional scale and local scale hydrogeological and other site assessments will be required for consideration of future development and/or changes in land use activities in any given area.

10. Finally, we recommend that this report be considered as a basis for the development of a comprehensive groundwater source protection plan and for future planning initiatives for the collective study area.