10. Water

Water quality is important to all elements of the ecosystem and encompasses both surface water and groundwater. Groundwater is considered a pathway whereby contaminants may be carried to surface waters. As a result, groundwater considerations are incorporated into the discussion of effects on the surface waters. Alteration to water flows is also discussed, but the significance of related environmental effects is assessed in Chapter 11 in the context of fish habitat. This chapter focuses on changes to surface water physical and chemical properties that may result from the Project.
 

10.1 Existing Environment

Water quality is linked both within and beyond the watershed boundary with the health, function and integrity of ecosystems, and with biodiversity (particularly freshwater life). Fundamental to the understanding of water quality is the characterization of watersheds, i.e. (the total catchment area over which precipitation is collected, stored and eventually discharged to the ocean). Under natural conditions, water quality changes occurring within a watershed are relatively isolated (i.e., changes will not cross watershed boundaries).

An aquifer is a geologic formation that is capable of yielding significant quantities of groundwater to wells and springs.

Groundwater occurs as subsurface flow through soil and bedrock. In the Voisey's Bay area the subsurface flows are generally contained within the watersheds. The characteristics of groundwater aquifers are influenced by both overburden thickness and composition, and bedrock characteristics. Bedrock features may direct flows in the same manner as river valleys. Although bedrock flows are more difficult to detect and measure, they can be assumed to be moving seaward, coinciding with the watershed drainage direction.

Baseline water quality conditions in the area have been potentially influenced since the 1940s by acid rain and increased human presence. Acid rain has greatly influenced the Canadian Shield and regions of eastern Canada. The slightly acidic and weakly buffered lakes in these regions are particularly sensitive (Environment Canada 1996). Emissions that contribute to acid rain have been decreasing since 1970, but the effects on water quality can still be detected. The water quality of several streams and ponds in the area exhibit sensitivity to acidification. Lower pH waters will tend to lead to elevated trace metal levels, and these may combine to reduce productivity of aquatic life.

Freshwater surveys have been conducted over a 2-3 year period. Natural water composition is typical of sub-arctic ecozones and can be described as soft, of low ionic strength and mostly mildly acidic. Despite exposed outcrops of highly mineralized rock and exploration activity, the average water quality from the Camp Pond/Reid Brook drainage area is not greatly different from that of the remaining eight catchments within the Water Assessment Area. All the ponds studied were oligotrophic and by definition were low in nutrients, resulting in low biological productivity.

Increased human presence is the result of improved access (snowmobiles, power boats, float planes and helicopters), proximity of local settlements (relocation to Utshimmasits), and regional mineral exploration activities. These events have the potential to affect water quality through the introduction of materials such as fuels or solid and liquid wastes. There is no evidence that increased human presence has caused detectable effects on water quality within the.
 

10.1.1 Enviromental Asessment Boundaries

The following Project activities will interact with eight watersheds in and adjacent to the VBNC Claim Block:
 

The environmental assessment boundary for water quality (Water Assessment Area) is defined by the eight watersheds that will interact with the Project (Figure 10.1). The watersheds and the corresponding drainages are:

Voisey's Bay Drainage

Kangeklualuk Bay Drainage

"I strongly recommend that the Proponent not just make generalized statements "Lakes are going to be affected in this way—rivers" but rather look at each drainage basin separately, because each system is separate and will have different kinds of effects. Each is a sort of operating unit—an operating system." (Isobel Heathcote, University of Guelph, Panel Scoping meeting in Sheshatshiu, May 14, 1997).

Kangeklukuluk Bay Drainage

Throat Bay Drainage

Anaktalak Bay Drainage

Residual environmental effects predictions are made for water quality in each of these eight watersheds.
 

10.1.2 Administrative Boundaries

Some of the regulated limits are presented in Table 10.1.

The amount of a substance in water is measured in milligrams per litre (mg/L). One milligram per litre can also be expressed as one part per million (1 in 1,000,000). An amount of 0.00 1 mg/L can be expressed as one part per billion (1 in 1,000,000,000).
 

The Department of Environment and Labour (NDOEL), Government of Newfoundland and Labrador, may also specify additional criteria as conditions of a Certificate of Approval. Water use is regulated under NDOEL through permitting requirements for activities within 15 m of a water body related to withdrawal of water, installation of intake structures, dams, and culverts, discharge of wastewater, and others.

Exceedances of CCME guideline values are common within the natural environment. This is particularly evident within the Water Assessment Area, due to site specific geological or terrain conditions. For example, during the VBNC water quality program, surface water and groundwater exceedances of CCME guidelines were recorded for pH, aluminum, copper, iron, and zinc.

The use of CCME guidelines is not appropriate for this area. These guidelines do not accommodate local, or even regional natural conditions. For example, aluminum and pH are typically outside of guideline limits for most of Newfoundland and Labrador. With respect to mining projects where the mineralized zones are present near surface, the natural elevation of many dissolved metals is typical for baseline water quality conditions. The CCME guidelines are therefore not used for comparison purposes. Additional discussion of the applicability of the CCME guidelines is provided in Sections 10.1.5.2 and 10.3.
 

10.1.3 Technical Boundaries

Laboratory analytical procedures and equipment used for measuring concentrations of water quality parameters have practical limitations. As noted above, the most common laboratory limitation is expressed as the limit of quantitation (LOQ). Only two parameters (pH and aluminum) had consistently measurable concentrations permitting the calculation of mean values and standard deviations. Median concentrations are therefore used to characterize surface water sampling station results at most locations. Although quality assurance and quality control (QA/QC) procedures demonstrated reliability of the data, there were some variations in the concentration of trace metals (including cadmium, copper, lead and zinc), especially when near the LOQ.

In several cases, winter sampling was precluded by one or all of the following conditions: \
 

At different times, attempts to auger through heavy ice were unsuccessful. Only one station (Station 2) was consistently accessible for winter sampling.
 

10.1.4 Data Collection and Methods

At stream stations, surface grab samples were collected from the centre of the fast flow area. Prior to sampling, field measurements of dissolved oxygen, pH, conductivity, and temperature were recorded. The water samples were collected in appropriate containers and preservatives added as required.

Pond water stations were located near the deep basin section of each pond. At these stations, a Niskin water sampler was used to collect between 3-5 samples per vertical section of pond, depending on the depth. For each station, samples were taken at the surface and near bottom. At shallow water sites (less than 10 m), one mid-depth sample was also taken. If the water was 10-20 m deep, two equally spaced (by depth) midwater samples were taken; and at deep water sites (20 m or greater), three equally spaced (by depth) midwater samples were taken. Field measurements were taken for dissolved oxygen, pH, conductivity, and temperature at various depths to provide profile data.

Groundwater samples were collected from a total of 60 overburden and bedrock monitoring wells (Figure 10.3). In early 1996, groundwater samples were collected from overburden and bedrock monitoring wells within the proposed North Tailings Basin, Option 5, Headwater Pond, and the proposed on-land mine rock and overburden disposal areas around the open pit area, including proposed stormwater and pit water retention pond sites. In late 1996, groundwater was sampled from wells installed at the perimeter of the proposed open pit.

To ensure groundwater samples were representative of in situ conditions, each monitoring well was purged to remove stagnant water. During well development, pH, temperature, and conductivity were periodically measured and purging continued until these readings stabilised or a minimum of three well volumes were removed. Groundwater samples (with the exception of those selected for analyses of mercury, total cyanide and Kjeldahl nitrogen) were filtered in the field using 0.45 micron filters. All groundwater samples were collected in clean bottles, with appropriate preservatives supplied by an analytical testing laboratory.
 

Streamflow data were continuously collected at six permanent stations in the Assessment Area. Three hydrometric stations were established on Reid Brook, Camp Brook, and Camp Pond in 1995. An additional nine stations (seven temporary and two permanent) were established throughout the Assessment Area in 1996, while in August 1997, a permanent station was established in the Option 5 watershed (Figure 10.4).
 

The permanent stations were established at the inlet and outlet of the proposed North Tailings Basin; the temporary stations were in place for the open water season, and were removed in October, 1996. Permanent stations are equipped with digital data loggers interfaced with Sutron 8200 data loggers. The Reid Brook station provides real time access to the data. Temporary stations are equipped with a single channel data logger. Data from the permanent stations are collected using quality control procedures, as outlined in the Environment Canada Hydrometric Field Manuals. The permanent stations were installed and maintained by EC personnel. Complete details are presented in JWEL (1997b).

Supplementary information from winter and spring runoff observations were also collected to record snow and ice depths, late winter snow densities, and break-up.

The Reid Brook watershed is the largest in the Assessment Area. This watershed has therefore received the most sampling effort of any single area. Water quality and hydrological data were collected from the following stations within this watershed:
 

Pond 64 was sampled in the 1996 program while two other ponds (Ponds 70 and 71) were sampled in the fall of 1997. Stream samples were collected from one station from 1995-1997 and four additional stations in 1997 (Stations 15, 39, 40, 43).

Hydrological and baseline chemistry data were collected from three pond stations (55, 56, 57) and three stream stations (21, 30, 31). In addition, two permanent hydrometric stations located within the watershed have been recording flow continuously since mid-August 1996. These stations are located above Pond 55 (Station 03NE004) and at the outlet of Pond 56 (Station 03NE005). Supporting data include spot flow measurements, temporary gauges, spring runoff monitoring and winter field observations.
 

10.1.5 Existing Conditions

The surface water and groundwater typically contain detectable traces of metals. Low concentrations of aluminum and iron are typical of natural waters in siliceous to mafic crystalline bedrock terrain associated with overlying organic soil and peat. The feldspar mineralogy, common to the anorthositic and troctolitic mafic rocks as well as granitic rocks within the area, typically release aluminum to groundwater and surface water. This occurs as a result of weathering processes in near neutral to weakly acidic conditions, such as occur in the Assessment Area. Iron, released by natural weathering processes, is also slightly soluble in the near neutral to weakly acidic groundwater and surface water environment. It is also slightly soluble in chemically reduced (low oxygen) groundwater due to infiltration through the peatland terrain common in the area. The peatland terrain can also increase iron solubility due to natural organic complexing.

Occasional occurrences of trace metals such as copper are expected in the Assessment Area. Both copper and nickel will occur at trace concentrations within the mafic mineralogy of the various intrusive rock suites. Accordingly, they may occasionally occur at slightly elevated background concentrations in some surface water and groundwater samples. Also, given the trace concentrations observed, the occurrences can be anticipated to be quite variable over time and between sample locations.

The major sources of dissolved ions in the surface water therefore likely reflect the minor inputs of groundwater. In areas with thicker overburden deposits, stream water will contain higher concentrations of dissolved ions compared to areas where the terrain is dominated by exposed bedrock and groundwater discharge is minimal. Weakly mineralized waters (low concentrations of dissolved ions) suggest that streamflow is dominated by surface runoff and groundwater discharge is a relatively small component of the overall flow.

The exploration activities conducted by VBNC have resulted in some localized disturbances in water quality. Increased sedimentation was measured in Discovery Hill Pond in 1995. This pond has no fish habitat, has naturally elevated trace metal concentrations, and is connected to Camp Pond by an intermittent stream. Changes to water quality in Camp Pond were not detected. At other locations, short term siltation has been linked to exploratory drilling (e.g., a small pond on the Eastern Deeps) but a permanent shift in water quality has not been detected at the downstream monitoring stations. All of these events were temporary and reversible.
 

10.1.5.1 Regional Characterization and Water Flows

The VBNC Claim Block is located on a peninsula that juts eastward into the Labrador Sea, with Voisey's Bay to the south and Anaktalak Bay to the north. Kangeklualuk Bay forms a marine inlet to the peninsula from the east. The interior of the peninsula is dominated by a series of prominent valleys (Fraser River Land Region) surrounded by rugged bedrock-dominated upland terrain (Saglek/ Hopedale Land Region). Regionally, the upland terrain is a relatively level plateau with elevations of 200-600 m. The valleys and marine inlets are the result of glaciation and subsequent erosion. The depth of lake basins typically ranges from 20-30 m below the surrounding ground surface.

Climate

Runoff is the water from rainfall or snowmelt that runs off the land into stream channels and ponds.

Climatic conditions affect water quality and quantity. Both precipitation and temperature vary over time and determine surface water runoff. Precipitation and temperature data, as well as other meteorological data, have been systematically collected in the Assessment Area watersheds since the summer of 1995. This discussion provides a brief overview of precipitation; a more complete description of climate is provided in Chapter 8.

Precipitation includes all forms of moisture falling from the atmosphere to the earth's surface.

In northern Labrador, most of the precipitation results from air masses transported from warm humid sources to the south, sometimes replenished by moisture from the Labrador Sea in the coastal locations. Climate data for northern Labrador include records for Nain and Hopedale, archived in the data bank of the atmospheric environment branch of Environment Canada. These records indicate that over half of the total precipitation in both Nain and Hopedale falls as snow. The Hopedale station has the longer continuous record, and provides an indication of the variability in precipitation. For the period of record, from the early 1940s to the early 1980s, the total annual precipitation ranged from 400 mm to nearly 1200 mm, with an average of just over 800 mm.

The temperatures in Hopedale and Nain usually fall below freezing in mid-October and stay below zero until May. This persistent winter cold results in a continuous snow cover for over six months. The snow tends to be blown off the high barren ground and to accumulate in the sheltered wooded valleys. In early summer, the temperatures in the Assessment Area are slightly higher than Nain. In the fall, the Assessment Area cools down earlier than Nain.

The precipitation in the Assessment Area watersheds can be expected to have the same pattern over time as Hopedale and Nain. Within the watersheds, considerable spatial variability is also likely. The upslopes facing the sea, as well as the higher ground in general, are likely to have more precipitation than either of the coastal stations of Nain and Hopedale.

Hydrology

Hydrological studies have been conducted across the Assessment Area to characterize surface water flow systems in the eight watersheds that discharge into five marine bays. Streamflow data have been collected from the Assessment Area since the summer of 1995. Longer term data were compiled from other northern Labrador hydrometric stations operated by Environment Canada. Records are maintained in Environment Canada streamflow database, HYDAT.

This description of flow patterns is based on data collected from two northern Labrador hydrometric stations since 1979 (Ugjoktok River below Harp Lake (03NF001) and Kanairiktok River below Snegamook Lake (03NG001). The Kanairiktok River station was closed in 1996. The annual flow pattern is similar for both the Ugjoktok and Kanairiktok basins because they share a similar precipitation and temperature regime, as well as similar physiographic characteristics such as land cover types (forest, barren, peatland, and lakes), elevation, slope and geology.

The seasonal pattern and variability over time that can be expected in the region is shown in Figure 10.5, using the recorded daily flow data from Ugjoktok River. Figure 10.5 is based on the daily flows from the 17 years of record. On average, as shown by the plot of the mean daily recorded flow, the highest flow in the year occurs in June (average June flow is over 600 m³/s). The maximum daily flow, however, approaches 1500 m³/s, and flows over 1200 m³/s have occurred several times. The minimum daily flow in June was just over 300 m³/s, and the minimum daily flow recorded to date was a late winter flow of only 3.6 m³/s.

The following general pattern of streamflow is expected for the Assessment Area:
 

Over the long term, flows can be expected to vary from year to year, sometimes within wet and dry cycles. The record for Ugjoktok River covers less than 20 years, which is considered short for predicting long term cycles. To assess these cycles, records from rivers with longer records elsewhere in Labrador, as well as with meteorological stations with longer records, such as Happy Valley-Goose Bay, can be used. The longer records suggest that on average, the early 1960s were dry. In the late 1970s to the mid-1980s, precipitation (especially snow) and flows were above average. The period since then, from mid-1980s to the mid-1990s, has been generally drier than average, with some wetter periods in the last year or two. The observations of local residents, as well as the record from the Ugjoktok River, are generally consistent with these overall trends.

Specific runoff is the quantity of runoff per unit area. It allows for comparison of flows among drainage areas.

The data suggest that the Assessment Area is slightly wetter than the Ugjoktok River and Kanairiktok Basin. This is probably due to the proximity of the sea. There are no precipitation data in or near the Kanairiktok River and Ugjoktok River, but it seems reasonable to expect that the interior is drier than the coast. The specific runoff of continuously gauged rivers at the site is shown on Figures 10.6 and 10.7 for 1995 and 1996, respectively. The record from Ugjoktok River has been added to the figures as a reference river for comparison. The specific runoff for temporary gauges located downstream at Headwater and Otter Ponds for the open water season in 1996, as well as for Camp Brook and Ugjoktok River are presented in Figure 10.8.

The 1996 data for the proposed North Tailings Basin is displayed in Figure 10.9. The relatively high runoff in the fall from the inlet brook to the North Tailings Basin is likely due to its small drainage area, barren terrain, and lack of upstream ponds. The hydrology of these basins and others in the Assessment Area is further described later in this chapter.
 
 

Regulation is the natural adjustment of flow that can occur when water flows through a pond or reservoir. High flows are reduced in magnitude and spread out in time.

The figures show that the pattern of runoff in the Assessment Area is similar to the regional pattern as represented by the Ugjoktok River station. The differences are due to the basin characteristics. Reid Brook has a relatively higher specific runoff than the Ugjoktok River in high runoff periods, as expected due to its smaller drainage area. The Camp Brook basin is also much smaller than the Ugjoktok basin, but the three large ponds (Headwater Pond, Otter Pond, and Camp Pond) regulate runoff from the basin.

Sublimation is the loss of water to the atmosphere from a snow pack. The water changes directly from its frozen state (snow) to water vapour.

The runoff data for 1996 can be used in an approximate water balance, by comparing the precipitation with the streamflow data. Specific runoff can be expressed as an average depth of runoff over a watershed, which represents the total available precipitation after all losses have been subtracted. The average runoff over a watershed over a year is referred to as the mean annual runoff (MAR). The difference between precipitation and runoff is the loss of moisture to the atmosphere through evapotranspiration and sublimation as snow.

Evapotranspiration is a term used to describe the combined effects of evaporation and transpiration. Evaporation is the direct loss of water to the atmosphere and transpiration is the indirect loss of water to the atmosphere through plants.

The precipitation data for Nain and the Assessment Area from November 1995 to October 1996 suggest that the total precipitation (rain and snow) was about 750-850 mm. The corresponding depth of runoff for the same period from the hydrometric stations ranged from 700 mm for the Camp Brook basin to about 820 mm for the Reid Brook basin. These values suggest that about 100 percent of the precipitation ran off, with no losses due to evapotranspiration or sublimation. This is considered unlikely. Evapotranspiration and sublimation could be expected to be lower in this region than in other areas of northern Canada because the mean monthly relative humidity is high (greater than 60 percent), there are large areas of barrens with little vegetation or snow cover, and the snow tends to accumulate in sheltered wooded valleys where there is less opportunity for sublimation. Nevertheless, evapotranspiration would not be zero. Assuming that some evapotranspiration and sublimation occurs, perhaps ranging from about 100-300 mm annually, depending on the particular location, the total annual precipitation over the Assessment Area from November 1995 to October 1996 was approximately 1000 mm.

The average flows for 1996 recorded and estimated from hydrometric stations within the Assessment Area are summarized in Table 10.2.

Estimates of flow outlined above were based on the MAR of both Camp Brook and Reid Brook. This estimate of average depth of runoff for 1996 can be used to estimate volume replacement rate. The rates of pond volume to inflow volume based on estimated MAR of 800 mm/yr is shown in Table 10.3. The drainage basin information based on the bathymetry of the ponds, the drainage area and annual precipitation of 1000 mm is summarized in Table 10.3. The pond flushing or volume replacement rate varies from 0.1-5.6 years.

Flood Patterns

Frazil ice is defined as the small ice crystals that form in turbulent water during freeze-up.

The factors leading to flooding in ponds and rivers in the Assessment Area include ice blockage in rivers or at outlets of ponds, spring runoff/snowmelt, and localized storms. Frazil ice particles may also form in rivers, cling to the riverbed, and accumulate to form ice blockages, leading to upstream flooding. The area flooded around ponds is related to the following:
 

Records and observations of water levels and flow dating to 1995 from the Assessment Area watersheds have been used to describe the possible extent of flooding.

Maximum water levels recorded at the Reid Pond hydrometric gauge indicated that the maximum change in elevation since summer 1995 was approximately 1.4 m. The high water levels on Reid Pond have resulted from high spring runoff, rather than ice blockage. The water level varies over the long term and could be expected to extend to the surrounding tree line. In some events, flooding may extend into the surrounding woods.

On Reid Brook, an ice blockage was observed 4-5 km downstream of the outlet of Reid Pond, causing flooding back along Reid Brook for approximately 2 km. Due to the channel geometry and physiographic characteristics of this area, there is a high potential for similar flooding in most years during the late winter-early spring as a result of such blockages.

In the Camp Brook sub-watershed, high spring water levels occur at Headwater Pond, Otter Pond and Camp Pond. Camp Pond has a relatively large drainage area. The outlet is relatively wide and the high degree of natural regulation upstream reduces the overall effect of flooding. The water levels as recorded on Camp Pond indicate that the maximum change in elevation on the pond for the period of record since summer 1995 is approximately 1.3 m. It could be expected that the long term change in elevation would be greater than this, with the water level on Camp Pond extending towards the surrounding tree line.

Elevated water levels on Camp Pond have resulted from two main factors: high spring runoff and ice blockage just downstream of the outlet of Camp Pond. The highest levels recorded have occurred in early May, when runoff has started, just before the ice blockage is released.

The highest levels in Otter Pond observed to date have occurred in the spring runoff period. The outlet of Otter Brook does not normally freeze completely in the winter. Observations to date suggest that the extent of flooding during the high spring runoff periods could extend towards or into the surrounding tree line. The outlet of Otter Pond is flat and marshy, and is flooded during high flow periods. In the spring, only small islands remain and the outlet becomes an extension of the pond for this period. The remainder of the reach from Otter Pond to Camp Pond, downstream of the flat marshy outlet of Otter Pond, is similar to Camp Brook. It would be expected that similar flooding would occur in this area, the difference being that the changes in elevations in the stream may not be as extensive due to the lower inflow volume.

Headwater Pond has the lowest ratio of local drainage area to surface area in the watershed. The local inflow volume is small, relative to the size of the pond. The outlet of Headwater Pond is narrower than that of Otter Pond and Camp Pond and the topography is not as flat. Although the inflow to Headwater Pond is less than that of Otter Pond, the fluctuation in water level could be expected to be similar based on the surrounding topography and hydraulics of the outlet of Headwater Pond. The reach between Otter Pond and Headwater Pond is relatively short and the area of land flooded is relatively small. The area of the reach closest to Headwater Pond is relatively flat and the extent of flooding in this area would be expected to be greater than the remainder of the stream. Most of the stream is steep and narrow and although the change in elevation may be higher, less area would be flooded. Flooding could be expected to occur during high flow periods. At the inlet to Otter Pond, the stream is affected by the backwater from Otter Pond, when pond levels are high.

Areas of potential flooding within the Reid Brook watershed would include the perimeters of all ponds, the braided section of Reid Brook upstream of the confluence with Camp Brook, level boggy areas around Camp Pond, along Pond 54 tributary, and surrounding the mouth of Reid Brook.

Peatland areas dominate the lower sections of Pond 67 and Southern watersheds, and the central portion of Throat Bay watershed. During high flow periods, all of these areas might experience flooding in proportion to the upstream basin area and the nature of any restriction of flow.

The topography of North Tailings Basin watershed is similar to Camp Brook and similar flooding patterns would be expected for the marginal areas of ponds and streams. There are fewer peatland areas within this watershed. Option 5 watershed has steeper topography that will tend to confine flooding and produce higher relative discharges.

Little Reid Brook, flowing into Anaktalak Bay, is flat and meandering in its lower reaches. Some flooding might occur, not only due to high runoff or ice effects, but also due to a backwater effect during high tide. During regular tidal cycles, flooding may occur from 0.5-1 km up the stream from the ocean.

Ice Formation and Melt Patterns

Natural ice conditions in the watersheds of the VBNC Claim Block can be expected to result from the typical processes that pertain to river ice formation and break-up in the region. Spring runoff and ice measurement data have been collected in the Assessment Area for 1996 and 1997. The discussion presented here also uses general considerations of northern climate, and longer term data from other Labrador locations, as well as referring to observations in the Assessment Area.

The time of freeze-up and breakup depends on the weather conditions and the flow regime. On the Ugjoktok River and Kanairiktok River, Environment Canada records show that freeze-up has occurred as early as mid-October, while spring break-up has occurred as late as mid-June. It can be expected that ice cover on the lakes would form earlier and break-up later than on rivers in the same climate. The duration of ice cover at the gauged station is usually greater than 180 days a year (Government of Newfoundland and Labrador 1992). Similar conditions may be expected in the watersheds of the Assessment Area. Flow records from the area indicate a decrease by November to December marking the beginning of the freeze-up. Spring break-up occurred during mid-April 1996 and a few weeks later in 1997. It is unlikely that ice forms and breaks up more than once during a single winter because the temperatures are consistently sub-zero. In the spring, when temperatures can fluctuate above and below zero, short episodes of break-up and refreezing will occur. Thus, the quantity of ice formed on the stream may be greater than if the ice cover were static until break-up. Rapids, bends or obstructions in the streams could lead to ice jams during freeze up or ice pileups during break-up periods.

The thickness of ice is a function of air temperature and flow conditions and is likely to vary in rivers and streams. In faster moving parts of a brook, the ice will initially form as frazil in turbulent water and will eventually agglomerate on the surface to form a continuous cover. In such reaches, the ice thickness will vary depending on individual site conditions, including channel geometry, roughness, flow, and slope. The thickness of ice on ponds in coastal areas of northern Labrador can be expected to be a metre or more by the end of the winter.

Hydrogeology

Hydrogeology is the study of the occurrence, movement and chemistry of groundwater.

The groundwater flow system originates as recharge within the upland areas and migrates outward toward the adjacent low areas of discharge in the valleys and coastal areas. Bedrock is of low permeability, and is typically several orders of magnitude less permeable than the granular surficial deposits within the valleys. Although the bedrock in the Assessment Area does not appear to support any notable zones of permeability that could be considered as aquifers, groundwater flow will be preferentially focused within linear, structural zones.

Hydraulic gradient is the change in water level elevation per unit distance in a given direction.

Monitoring wells installed throughout the site indicate that the water table is at or within a few metres of the surface in the valley areas across the Assessment Area. Beneath the bedrock ridges, the water table ranges from 5-20 m below surface and strong downward hydraulic gradients occur.

The baseflow is that component of streamflow which is derived from groundwater discharge to surface water.

The groundwater discharge typically maintains baseflow within the various tributary streams. This is most noticeable in areas of more extensive overburden cover, specifically in streams originating within the areas of moraine terrace and the area of extensive sand and gravel deposits within the Reid Brook Valley where spring-fed streams can be seen to arise.

The surficial geology of the Assessment Area, as shown on Figure 10.10, is subdivided into terrain dominated by unconsolidated surficial deposits and bedrock terrain which has been sculpted by glaciation. The bedrock terrain forms the uplands, while the surficial deposits are mainly in the valleys, and include moraines, kame terraces, glaciofluvial and glaciodeltaic deposits (more recent floodplain deposits and peat lands). The available permeability information indicates that some areas of coarse grained surficial deposits, and specifically the areas of kame and glaciofluvial-related sand and gravel in the Reid Brook Valley (extending north from Reid Brook to Anaktalak Bay), constitute water-bearing aquifers bounded within the bedrock valleys.

Moraine deposits are sand, gravel or mixed sizes of material which were left on the landscape as a result of glacial action.

Glaciofluvial deposits underlie much of the Reid Brook Valley extending from Anaktalak Bay to near Voisey's Bay in the south. The source of much of the deposits appears to have been outwash from the Reid Brook Valley to the west from where deposition occurred both to the north and south within the Reid Brook Valley. Beneath the northern half of the valley, extending from Reid Brook to Anaktalak Bay, the deposits tend to be coarser-grained sand and gravel. This area is considered to contain the most extensive deposits of high permeability material and the most significant aquifer system within the Assessment Area. The permeable nature of this aquifer system is also indicated by the relatively high baseflow discharge of Little Reid Brook.

Hydraulic conductivity measures the ability of a porous medium to transmit fluid.

Moraine deposits occur within the areas of low relief such as the eastern flank of the Reid Brook Valley and Headwater Pond watershed areas. Moraines are most extensively developed on the southern and western facing hillsides. These till deposits tend to be quite granular and are characterized by a relatively low hydraulic conductivity of approximately 1 x 10^-4 cm/s. The finer grained tills associated with some of the basal lodgement deposits have even lower hydraulic conductivities of about 1 x 10^-5 cm/s or less. The silty and clayey deposits associated with glaciofluvial and glaciodeltaic deposition are also associated with hydraulic conductivity of about 1 x 10^-5 cm/s or less.

The bedrock-dominated terrain comprises approximately half of the Assessment Area, and consists of exposed bedrock or bedrock with a thin veneer of organic deposits and granular soil. The bedrock geology has a significant influence on the concentrations of metals in natural waters. The bedrock geology underlying the Assessment Area is subdivided into two major rock types: metamorphic gneiss and crystalline plutonic rocks. The gneisses occupy the central part of the Assessment Area and are flanked to the east and west by plutonic rocks.

The bedrock geology of the area is shown in Figure 10.11. The various structural lineaments shown are potential fracture pathways within the otherwise massive, crystalline bedrock. Faulting is considered to be the structural feature of most importance for the hydrogeology of the Assessment Area. Fault zones are potentially higher permeability zones compared to the surrounding rock. Faults and related fracture zones are evident from contact offsets or lineaments within the bedrock surface. The shallow, near surface bedrock (10-20 m depth) has quite variable permeability, with the hydraulic conductivity ranging from 1 x 10^-7 to 5 x 10^-3 cm/s. In the area of the Ovoid, the bedrock surface appears to be less permeable (1 x 10^-7 to 1 x 10^-5 cm/s), probably due to the thick cover of glacial till (20-30 m), which has limited the influence of weathering processes on the rock surface. The bedrock becomes progressively less permeable with depth, with hydraulic conductivity typically less than 1 x 10^-5 cm/s. Much of the deep rock mass has values of 1 x 10^-6 to 1 x 10^-7 cm/s, which is essentially impermeable to groundwater seepage. Groundwater quality data also indicates that the bedrock permeability is low (refer to Section 10.1.5.2).

Estuarine Features

An estuary is an area where freshwater from rivers meets and mixes with salt water from oceans.

Three general forms of estuaries occur in the Assessment Area watersheds: dynamic large sand deltas; bedrock/boulder/cobble-dominated forms; and intermediate forms ranging within these two distinct forms.

Reid Brook and Kogluktokoluk Brook discharge to Voisey's Bay over a long, wide, unconfined sand delta (2 km long and 2 km wide). Sand from extensive glacial deposits within the watershed is continually transported onto the delta, forming and reforming the channels. The shallow water over the delta produces an extensive estuarine mixing zone that extends from the edge at low tide and possibly several kilometres up the brooks at extreme high tide. The total drainage area of the brooks (1266 km²) results in an annual average discharge of approximately 35 m³/s into Voisey's Bay, causing the estuarine influences to extend for some distance beyond the delta and into the bay. A discussion of the environmental effects of this freshwater lens on seawater quality is provided in Chapter 12.

Little Reid Brook also discharges over a large post-glacial shallow sand beach at Edward's Cove that extends 200 m into Anaktalak Bay. The small watershed (15 km²), however, produces an annual average discharge of less than 0.5 m³/s, which has not led to a large delta formation.

Option 5 and Pond 67 watersheds empty over a gradually sloped sandy shore, but again the small drainage areas and the lack of sandy deposits curtail delta formation where they discharge into Kangeklukuluk Bay.

The stream from the proposed North Tailings Basin drains 34 km² and discharges at the head of Kangeklualuk Bay. The mouth of the stream is set in a rocky shore with virtually no delta formation. The shore slopes off quickly to deeper water in the bay. Pond 65 and Throat Bay watersheds (9.6 km² and 35 km², respectively) empty over bedrock/boulder dominated shores with no delta formation.
 

10.1.5.2 Summary of Water Quality

Arsenic and cobalt were not detected in any of the water samples.

Lead was detected in every watershed. Cadmium was detected in Reid Brook, North Tailings Basin, Pond 65 Brook, Throat Bay Brook and Little Reid Brook Watersheds. Iron was detected in all watersheds and exceeded guidelines for the full range of values in the Southern Watersheds, a boggy area. The upper range of iron was over guideline in two additional watersheds, Little Reid Brook and North Tailings Basin. Zinc was detected in all watersheds and at levels exceeding guidelines in the Southern Watersheds area.

The pH values of all watersheds had an adjusted range of 6.2-6.9. Only Pond 67 had values that were always at or above the guideline minimum level of 6.5. Total suspended solids were low in most watersheds with a couple of exceptions. Most of the elevated values were recorded in Reid Brook and Little Reid Brook. Elevated levels of suspended solids were observed in these brooks following rain events. While exploration activity on Reid Brook might be related to occasional increased Total Suspended Solids (TSS), this is not the case for Little Reid Brook, particularly in 1995 and 1996, as there was no activity along the brook.

Summary of Precipitation Quality

All surface water and groundwater within the Assessment Area is directly derived from precipitation. Once fallen, the precipitation chemically interacts with the soil, rock and vegetation that it comes into contact with, dissolving various amounts of major ions and heavy metals. The precipitation and geochemical reactions determine the water quality characteristics determined from the groundwater and surface water sampling programs.

The Atmospheric Environmental Service of Environment Canada maintains a precipitation monitoring station in Happy Valley-Goose Bay, Labrador (Site Identification No. CAPM84152A), which is the closest station to the Project. The annual summary of precipitation chemistry data for this station from 1990-1996 was reviewed to provide a basis for comparison with the results of the groundwater and surface water quality monitoring. The concentration range for the 6-year period of precipitation monitoring, expressed as weighted mean precipitation values, is summarized in Table 10.6.

As indicated by the low pH units, the precipitation is moderately acidic. The various major ions occur at concentrations of less than 1 mg/L. The total dissolved solids in the precipitation is 1.5-2.0 mg/L, assuming a carbonic acid-bicarbonate concentration of 0.7 mg/L (based on an atmosphere CO₂ pressure of 10^-3.5 bars). This range represents the baseline concentrations. Initial neutralisation of the slightly acidic nature of the precipitation will occur when it contacts the ground.