Reid Brook Stem Subwatershed
Hydrology
About 75 km2 (greater than 50 percent) of the basin lies upstream of Reid Pond. Downstream of Reid Pond, Reid Brook makes a right angle turn to the south, draining the remainder of the basin, as it meanders to Voisey's Bay. The area above Reid Pond is high, rugged and barren; below Reid Pond the area drained is low lying and predominantly wooded.
The highest flows at the hydrometric station on Reid Brook occurred during the spring runoff months of May to July, with a peak recorded in June, 1996. Low flows occurred during the period from late December to April, in both 1996 and 1997 (Figure 10.6). In late winter, ice in the portion of the brook below Reid Pond appears to limit the amount of flow downstream. It can be expected that the snow cover would remain in the upper portion of the watershed area above Reid Pond for longer periods during the year due to the higher elevation. For the lower portion, it can be expected to be similar to the Camp Brook subwatershed. In 1996, the spring break-up of ice at the outlet of Reid Pond started in late April and continued until mid-June.
The estimated mean annual runoff (MAR) above Reid Pond in 1996 was about 840 mm/yr, compared with 690 mm/yr for the Camp Brook subwatershed and 660 mm/yr for the Ugjoktok basin. The higher runoff compared with the Camp Brook subwatershed is likely a result of several factors, including its higher elevation and less sheltered location. The Camp Brook subwatershed is in a shallow bowl surrounded by hills; not only is it more sheltered from the precipitation-bearing winds, but it may also have greater evapotranspiration from the larger areas of forest.
The flows in the Reid Brook/Reid Pond subwatershed vary much more than those in the Camp Brook subwatershed. This difference in pattern occurs because Reid Brook basin has more barren area and less natural regulation.
Surface Water Chemistry
A "thermocline" is the temperature gradient or layer of water where temperature changes rapidly with depth.
The average depth of Reid Pond (Pond 50) is 10.6 m, with a maximum depth of 65.3 m. Water in this pond was very clear. Field pH ranged from 6.45-6.95, whereas conductivity ranged from 7.5-9.0 mmhos/cm. Hardness, nutrient concentrations (no detection of ammonia and phosphorus) and specific conductance were all very low, indicating oligotrophic conditions with primary production co-limited by nitrogen and phosphorus. A thermocline was developing at approximately 10 m in July. In September there was little evidence of a thermocline with only the top three metres slightly warmer than at greater depths.
Along the main channel of Reid Brook, there are four water quality stations located on the tributary flowing into Reid Pond, down to the lower end of Reid Brook (1, 2, 24 and 7). These stations were established to detect changes caused by tributaries joining the main channel.
In general, Reid Brook had pH levels ranging from 6.4-7.0, with higher levels in the summer months (Table 10.4). Total suspended solids were extremely low. Nutrient concentrations (orthophosphate and nitrate) were very low indicating nitrogen and phosphorus are co-limiting primary production, and hardness levels were very low (less than 18 mg/L), indicating a low buffering capacity.
Probable Surface Water - Groundwater Relationships
The Reid Brook watershed arises from the bedrock-dominated western highlands, then enters the overburden-dominated central valley area. Monitoring of the surface water quality along the course of Reid Brook indicates water quality trends that appear to be related to groundwater discharge.
The water quality results from three sample locations indicate a significant change from the outfall of Reid Pond (Station 2) to the downstream sample location within the central, alluvial infilled valley (Station 3). The surface water discharging from Reid Pond at Station 2 had an average total dissolved solids (TDS) of about 20 mg/L which is about 10 times that of precipitation. The average TDS of the water increased from 20 mg/L at Station 2 to 31 mg/L at Station 3, associated with an increase in bicarbonate from average concentrations of 2.6 mg/L to a downstream concentration of 6.5 mg/L. There was also an increase in the pH range from 6.3-6.6 at Station 2 to 6.4-6.9 at Station 3. This change in water quality is interpreted to originate from a large increase in the groundwater baseflow to the stream from the alluvial deposits within the central valley area. These materials are the main groundwater-bearing deposits within the VBNC Claim Block.
Downstream, at Station 7, the water quality was similar to that of Station 3, but elevated chloride concentrations of up to 9.2 mg/L (accompanied by sodium concentrations of up to 7.1 mg/L) occasionally occurred. This was likely the effect of wind blown sea spray carried inland from the coastline and associated dilution and drainage into the stream course.
Reid Brook, Camp Brook Subwatershed
Hydrology
This subwatershed represents 15 percent of the Reid Brook drainage basin, and is the largest local watershed contributing to the lower part of Reid Brook. It drains an area east to west of about 26 km2 and includes Camp Pond, Otter Pond, and Headwater Pond. The bowl-shaped subwatershed is covered by more wooded area than barren and drains elevations extending to 250-300 m in the upper portion of the watershed.
The highest flows in the period of record at the hydrometric station on Camp Brook occurred during the spring runoff months of May to July, with the peak in June 1996. Low flows occurred during the period late December to April with zero flow recorded for most of February and March in both 1996 and 1997. The zero flow recorded in Camp Brook can be attributed to ice blocking the flow at the upstream part of the brook near the outlet of Camp Pond. The water flowing into Camp Pond during this period is held back by the ice, leading to a rise in water levels. The record of water levels in Camp Pond for this period shows this expected rise.
As noted above, the estimated MAR in the Camp Brook subwatershed in 1996 was about 690 mm/y. The basin was slightly wetter than the Ugjoktok basin for the equivalent period, which was about 660 mm/y (close to the long term average). The increased runoff compared with Ugjoktok River is most likely the result of the proximity of the Camp Brook subwatershed to the sea.
The pond storage in the Camp Brook subwatershed provides natural regulation, resulting in flows that are less variable than would otherwise be expected, given the small drainage areas. The brooks at the outlets of Headwater, Otter, and Camp Ponds all show a similar pattern of runoff. The pattern of daily flows recorded at the hydrometric station on Camp Brook is similar to that for Ugjoktok River station despite the fact that the Ugjoktok basin is over 300 times larger (7570 km2 compared with 24.3 km2 for Camp Pond).
Ice thickness on each of the ponds increased from January to March, with a maximum recorded ice thickness of just over 1 m by late winter. In 1996, the spring break-up of ice just downstream of all three ponds started around April 15 and continued until June 11 at Camp Pond and Otter Pond. The outlet of Headwater Pond was not completely free of ice until June 20. At the station on Camp Brook, the ice began to break-up about 2 weeks later (May 2) and was completely free of ice on June 19.
Surface Water Chemistry
Camp Brook subwatershed is divided into three stream sections: Headwater Pond to Otter Pond, a length of (150-200 m in length and, dominated by large boulders with very low quantities of fines, sands, or gravel) (Station 6), Otter Pond to Camp Pond (approximately 1000 m) (Station 5), and Camp Pond to Reid Brook (Stations 3 and 4). The average depth of these ponds range from the deepest at Headwater Pond (average depth 10.3 m, maximum depth 32.8 m) to the shallowest at Camp Pond (average depth 3.5 m, maximum depth 11.9 m). These ponds are very clear with Secchi disk measurements ranging from 4.5-7 m.
The pH in Camp Brook was 6.3-6.9, with slightly higher values in the summer months (Table 10.5). Total suspended solids were very low. Nutrients (orthophosphate and nitrate) were very low, indicating nutrient deficiency for primary productivity. Hardness was low (less than 10 mg/L), indicating a low buffering capacity.
The pond pH values were similar to the stream values and ranged from 6.2-6.9 (Table 10.5). Surface pH values increased slightly from the July to the September sampling period. Field conductivity ranged from 10.8-16.7 mmhos/cm. Hardness, nutrient concentrations (nitrate, ammonia and phosphorus measurements mostly below LOQ) and specific conductance were all very low, indicating oligotrophic conditions with primary production co-limited by nitrogen and phosphorus. A thermocline developed during the summer months for both Headwater Pond and Otter Pond. In the shallower water of Camp Pond no thermocline developed, even though there were surface/bottom temperature differences.
Groundwater Chemistry
The groundwater investigation program for the ovoid/mill site area included sampling a total of five monitoring wells. The groundwater was weakly mineralized with a TDS ranging between 40 and 91 mg/L and a neutral to slightly alkaline pH of 7.1-7.7. There was little variation in the principal dissolved constituents and trace metals concentrations between the overburden and bedrock water. The major dissolved constituents includes sodium (2.8-8.1 mg/L), calcium (4.2-16.7 mg/L), bicarbonate (15-60 mg/L as CaCO3), and sulphate (8-13 mg/L). Chloride was not detected above the analytical method detection limit of 1 mg/L in any of the groundwater samples. The sampling results indicated that the groundwater quality is a characteristic sodium-calcium-bicarbonate water, typical of shallow groundwater conditions within the Assessment Area.
The groundwater contained traces of aluminum (0.019-0.0.26 mg/L) and iron (0.031 to 0.42 mg/L) at concentrations similar to the water within the North Tailings Basin watershed (discussed below). Copper concentrations were in the range of 0.002-0.006 mg/L. Nickel concentrations were low (less than 0.002-0.007 mg/L). In one anomalous groundwater sample (BH96-34B), mercury was detected at a concentration of 0.00013 mg/L. Traces of lead (0.0001-0.0004 mg/L) and zinc (0.004- 0.009 mg/L) were detected in the water samples. Concentrations of the remaining metals in the groundwater were generally below the LOQ.
Groundwater - Surface Water Relationships
The stream water from both Headwater Pond (Station 6) and Otter Pond (Station 5) were quite similar, being very weakly mineralised TDS (9-42 mg/L) and of near neutral pH (6.3-6.8). The water contained low concentrations of calcium (0.9-1.7 mg/L), sodium (1.1-2.1 mg/L), bicarbonate (3-5 mg/L), and sulphate (0.7-4 mg/L), and was quite similar in concentration to that of the surface water from the Kangeklualuk Bay watershed (discussed below). The concentrations of the major ions were several times less than that of the groundwater, indicating that groundwater discharge is a small component of the surface water compared to direct catchment of precipitation and runoff.
The water downstream at the outfall of Camp Pond (Station 4) had a slightly higher TDS (12-50 mg/L), and the concentrations of calcium (1.0-2.5 mg/L), sodium (1.2-2.3 mg/L), and bicarbonate (4-8 mg/L) were also slightly higher than the upstream sample locations. These concentrations indicated that Camp Pond drainage receives a slightly higher component of groundwater discharge than does Otter Pond and Headwater Pond. This is possibly from runoff from the comparatively large, overburden-dominated area of the contributing watershed north of Camp Pond, where groundwater discharge from the glacial sediments would provide a greater component of the watershed baseflow compared to that of Otter Pond and Headwater Pond.
Pond 54 Subwatershed
The Pond 54 subwatershed is located just south of and parallel to the Camp Brook subwatershed and drains an area of approximately 15 km2. It discharges to the lower portion of Reid Brook. The area is a bowl-shaped, wooded valley similar to the Camp Brook subwatershed but at a slightly lower elevation. Part of Eastern Deeps area also drains into this subwatershed.
Spot flow measurements showed that this basin has a specific runoff similar to the Camp Brook subwatershed. The flows would be expected to be more variable due to less natural regulation.
Surface Water Chemistry
The average depth of Pond 54 is 7.5 m, with a maximum depth of 28.0 m. Water is very clear, with Secchi disk measurements averaging 7 m. Field pH ranged from 6.27-7.41, and field conductivity ranged from 10.5-12.1 m mhos/cm. Hardness, nutrients and specific conductance were all very low, indicating oligotrophic conditions with primary production co-limited by nitrogen and phosphorus (Table 10.4). During July sampling, a thermocline was developing at 6-7 m. In September, a well developed thermocline existed between 11-13 m.
The small tributary, located to the south of the Ovoid (Stations 33 and 25), drains into a larger stream (Station 13) that flows from Pond 54. In general, tributary water was slightly acidic and very soft, with low levels of hardness and conductivity, and thus low buffering capacity for pH changes. Low or undetectable concentrations of nitrites and nitrates, ammonia, and phosphorus indicated that both nitrogen and phosphorus are co-limiting primary productivity in the stream environment.
This tributary had concentrations of a few trace metals that were above most other Assessment Area locations. This is consistent with the proximity of this tributary to the Ovoid, indicating presence of metals close to the surface. Iron concentrations in the tributary were high.
Probable Surface Water - Groundwater Relationships
Surface drainage from the ovoid area is directed toward Camp Pond from the northern half of the area while the southern half drains southward through a large area of bog towards Reid Brook. Surface water samples were collected at two locations on the southern drainage courses (sample location Station 33, where the stream passes the southern end of the proposed open pit area, and sample location Station 25, at a point about 2 km downstream within the area of bog).
The water quality from the two sample locations was essentially the same, being weakly mineralised (TDS 26-39 mg/L) with a near neutral pH (6.2-6.8). The major ion composition of the water included calcium, sodium and bicarbonate. Slightly elevated levels of iron (0.16-2.4 mg/L) were present in the water, which is relatively typical of areas dominated by bog.
The average TDS concentration at Station 33 was 34 mg/L, which is approximately half that of the overburden groundwater (72 mg/L). Similarly, average calcium concentrations (4.3 mg/L) in the surface water were half of the overburden groundwater (8.0 mg/L). The average sulphate concentrations in the stream water (8 mg/L) were similar to the overburden groundwater (10 mg/L). The average bicarbonate concentration (10 mg/L) and sodium concentration (2 mg/L) in the upstream water sample were 4-6 times, respectively, less than the overburden groundwater concentrations of 42 mg/L and 12.5 mg/L. The chemistry of the surface water therefore suggests that shallow groundwater discharge from the overburden deposits at the ovoid comprises a relatively important component of the stream water in this area.
Baseline Groundwater Chemistry - Ovoid Area
Groundwater samples from both the overburden and bedrock were collected from both monitoring wells and drive point piezometers (temporary monitoring wells) on several occasions throughout 1996.
The groundwater quality within the overburden and shallow bedrock was similar to that of the other areas across the Assessment Area. The overburden groundwater was weakly mineralised with a TDS ranging from 51-98 mg/L and slightly acidic to moderately alkaline pH of 5.6-8.8. Two anomalous values of 9.0 and 9.5 were recorded but these values will be confirmed with additional monitoring. The bedrock groundwater had a slightly higher TDS of about 69-113 mg/L and was slightly to moderately alkaline (pH 7.6). The higher pH values of up to 9.8 occured the groundwater from deeper in the bedrock.
The principal dissolved constituents in the overburden and bedrock groundwater included calcium (less than 0.1-118 mg/L), sodium (3.1-152 mg/L), and bicarbonate (11-145 mg/L as CaCO3), with concentrations increasing with depth in the bedrock. A comparatively distinct trend of increasing sodium concentrations with depth associated with sodium-bicarbonate type water was noted. Sulphate concentrations in the overburden groundwater varied between less than 2-18 mg/L. In the deep bedrock groundwater, sulphate was also a dominant anion, with a maximum concentration of 500 mg/L recorded in sample I2-3 at a depth of 200 m. The comparatively high sulphate was likely associated with the high sulphide mineral content in the bedrock in the vicinity of the proposed open pit. The chloride content typically ranged from 1.3-9.1 mg/L. Two anomalous occurrences of chloride occurred in overburden groundwater samples where chloride concentrations of 18 mg/L and 72 mg/L were reported for samples FFC4 and FFC6, respectively.
The general increase with depth of the concentrations of the principal dissolved constituents indicated that the groundwater is slow moving at depth. There is little interaction with the shallow groundwater and surface water flow systems. The composition of the groundwater was typically a calcium-sodium bicarbonate water. Sodium was the principal dissolved cation in the groundwater at depth. This was also indicated by an increase in TDS and, hence, the specific conductivity of the water. The relative absence of chloride at depth, compared to increased sodium concentrations, indicated that the sodium reflects groundwater interaction with the bedrock. This is due in part to long groundwater residency times because the bedrock permeability is low. With the exception of a few deep sulphate dominated samples, the groundwater in the Ovoid area had the same chemical composition as elsewhere within the areas of investigation.
Elevated concentrations of aluminum (0.015-2.7 mg/L) and iron (0.03-14.0 mg/L) were recorded. This is typical for the nature of the groundwater within the Assessment Area. Concentrations of both of these parameters were higher in the overburden groundwater. Copper and lead concentrations were in the range of less than 0.0005-.012 mg/L and 0.0001-.0094 mg/L. Trace level concentrations of other metals such as nickel (less than 0.002-.090 mg/L) and zinc (less than 0.002-.039 mg/L) were recorded in the groundwater. Concentrations of most heavy metals in the groundwater were generally below the LOQs.
Southern Watersheds
Hydrology
The watershed is at a generally lower elevation than the Camp Brook subwatershed and is generally flatter. Spot flow measurements suggested that the runoff is probably similar to other gauged rivers in the Assessment Area. The two large ponds in the watershed are likely to provide natural regulation, suggesting that the runoff pattern may be similar to that of the Camp Brook subwatershed.
Surface Water Quality
Water quality was monitored at one stream station (Station 26) in 1996 and 1997. The waters were slightly acidic as pH ranged from 5.8-.7. TDS ranged from 22-74mg/L. Most parameters were similar to those for the neighbouring watersheds with the exception of elevated aluminum and iron. This may be a reflection of the bog conditions in the area.
Probable Surface Water - Groundwater Relationships
Stream sampling in the Southern watersheds was limited to one location
(Station 26). These data indicated that the water is very weakly mineralized
(TDS of 9 mg/L) with very low concentrations of major ions. Again, the
water quality data was similar to data collected throughout the Assessment
Area, which indicated that surface water quality typically reflects surface
runoff-dominated conditions with a minor groundwater component.
Hydrology
The watershed that contains the proposed North Tailings Basin consists of the main basin (Pond 55), lower basin (Pond 56), and the north basin (refer to Figure 10.7 for locations). The watershed drains about 34 km2, with about half above the proposed North Tailings Basin, and half between the Lower Basin and Kangeklualuk Bay. There are about equal parts of wooded and barren areas, with a higher proportion of barrens in the upper reaches, and at higher elevations than in lower portions. There are two other large ponds near the mouth.
The catchment upstream of the North Tailings Basin had a more variable response than any of the other gauged basins. It is representative of small barren basins with little natural regulation. The record for the station at the outlet showed the regulating effect of pond.
In 1996, spring break-up of the ice just upstream of the inlet to the main basin started April 29, while just downstream of the outlet of the basin it had already begun on April 18. The later start in break-up is probably due to the higher elevations of the upstream location. The end of the break-up for both the outlet and inlet was around June 11.
Surface Water Chemistry
There are three main ponds located in the watershed, two located close together (Ponds 55 and 56), and a third located farther downstream (Pond 57) close to Kangeklualuk Bay. The first two ponds are deep, the average depth ranging from 13.5-20 m, with a maximum depth ranging from 47-51 m. The downstream pond (Pond 57) is much shallower with an average depth of 6 m, and a maximum depth of 21.1m. Water clarity on all three ponds was high with Secchi disk measurements of 5-7 m.
Field conductivity ranged from 9-13.2 mmhos/cm. Hardness, nutrients (nitrate, ammonia and phosphorus) and specific conductance were all very low, indicating oligotrophic conditions with primary production co-limited by nitrogen and phosphorus. In July, surface waters were warmer than at greater depths for the main basin, however no thermocline had formed. A thermocline was formed for the third pond at 2 m. In September, all three ponds had thermocline development at approximately 3-8 m.
The brook downstream of North Tailings Basin (Stations 21, 30 and 31) had pH levels of 6.4-6.8. Total suspended solids were very low and nutrients (orthophosphate and nitrate) were below LOQ, indicating co-limitation of primary production. Hardness was low (less than 12 mg/L), indicating a low buffering capacity.
Groundwater Chemistry
Groundwater samples from both the overburden and bedrock were collected from the North Tailings Basin area between October 30 and November 6, 1996. The samples were taken from selected geotechnical monitoring wells at the locations of proposed Dams N1 through N6.
The overburden and bedrock groundwater was weakly mineralised with TDS concentrations of 11-23 mg/L (compared to TDS of 1.5-2.0 mg/L in precipitation), with the higher concentrations tending to occur at depth. The pH was near neutral to alkaline, ranging between 6.6-9.3. The upper end of this range (9.0-9.3) occurred in only two samples with the general range being between 6.6-8.5.
The major dissolved constituents of the groundwater included sodium, calcium, bicarbonate, and sulphate. Concentrations of potassium and magnesium in the groundwater were also typically low. Overburden and shallow bedrock groundwater tended to be more calcium bicarbonate-dominated water. At depth, the groundwater tended to have a sodium bicarbonate composition. This deeper water also tended to be within the higher range of TDS, hence it is more conductive.
The increase in sodium concentrations in groundwater with depth likely reflects cation exchange interactions between groundwater in fractures and the adjacent rock mass, which is dominantly composed of plagioclase feldspar minerals that could be a potential source for the sodium. The sodium bicarbonate composition likely also reflects long-term residency times within the bedrock allowing the processes to occur (due to the low permeability), hence causing slow groundwater circulation conditions.
The groundwater contained traces of aluminum (0.015-0.65 mg/L) and iron (0.029-0.45 mg/L), which is typical of water in siliceous to mafic crystalline bedrock terrain associated with overlying organic soil and peat. Copper concentrations were less than 0.002-0.009 mg/L, with one anomalous concentration of 0.043 mg/L encountered in a sample from well 96-20B. With this exception, the copper concentrations in approximately half of the groundwater samples were between 0.002-0.01 mg/L. Concentrations of nickel varied between less than 0.002 and 0.011 mg/L. Traces of cadmium (0.0003-0.0004 mg/L) and zinc (0.004-0.032 mg/L) were detected in three of the water samples. Concentrations of the remaining heavy metals in the groundwater were generally below the LOQ.
Surface Water - Groundwater Relationships
The water discharging from the proposed North Tailings Basin at the sample location (Station 31), which is also representative of the lake water, was very weakly mineralised with TDS concentrations of 11-16 mg/L. The average TDS concentration of 13 mg/L was typically about 4-5 times less than that of groundwater. The pH of the water was very weakly acidic, varying between 6.4-6.8. The average calcium concentration in the surface water at this location was 1.2 mg/L, compared to average groundwater concentrations of 6-7 mg/L. Similarly, average sodium concentrations (0.9 mg/L) in the surface water were much less than that of groundwater (11-12 mg/L). The major anions in the surface water were bicarbonate (2-3 mg/L) and sulphate (2-9 mg/L). The upstream surface water samples (SWS-5 at Dam N4 and SWS-6 at Dam N5) indicated TDS concentrations of 17-23 mg/L with a neutral pH of 7, which are both slightly above the conditions of the lake water discharging from the basin at Station 31. These results indicated that significant dilution from direct precipitation occurs in the proposed North Tailings Basin.
The surface water quality from the North Tailings Basin sample locations indicated that the water is largely derived from surface runoff of precipitation with little influence from groundwater discharge. The composition of the dissolved constituents in the surface water (calcium bicarbonate water) suggested that most of the groundwater discharge to the surface water is derived from the shallow, relatively more permeable overburden and weathered bedrock horizon. The deep, sodium bicarbonate groundwater appears to have very little influence on the surface water quality of the North Tailings Basin, indicating that the deep groundwater is a very small component of the overall groundwater flow system and discharge to surface water.
Station 30, located about 1.5 km downstream from the proposed North Tailings Basin, receives the combined drainage from the basin watershed and the large overburden-dominated valley to the south of the proposed North Tailings Basin. Here, the water quality was slightly more mineralised (TDS of 16-19 mg/L) with slightly higher calcium (1.3-3.1 mg/L) and bicarbonate (3-7 mg/L) concentrations. The composition of the water at this location indicated a slightly greater influence of the shallow groundwater discharge that originates from the overburden within the valley to the west. This interpretation is supported by the field observation of groundwater baseflow feeding streams within this area.
The surface water quality of the combined watershed at its point of
discharge to Kangeklualuk Bay (Station 21) was similar to that at Station
30 due to the net effect of surface runoff and groundwater discharge within
the proposed North Tailings Basin watershed. The relative concentration
of the groundwater and surface water chemistry indicated that the surface
water was dominated by surface runoff. Groundwater discharge was a relatively
small component of the overall streamflow.
Pond 65 Watershed
Hydrology
This watershed drains an area of about 10 km2. The watershed contains a series of ponds which drain to Kangeklualuk Bay. The elevations drained are lower than the watersheds described above. The area is predominantly wooded with some barren areas at the higher elevations. The hydrological response would be similar to the Camp Pond subwatershed.
Hydrological and baseline chemistry data were collected from Pond 65 and Stream 16. The hydrological conditions in this subwatershed are expected to be similar to those which drain low elevations close to the sea. The brook in the lower part of the basin would be expected to show the effect of natural regulation within the large ponds in the area.
Surface Water Chemistry
Stream water at Stations 15 and 16 had a pH ranging from 6.4-6.8. Low nutrient concentrations indicated nitrogen and phosphorus were co-limiting primary production. Low hardness indicated low buffering capacity.
The average depth of Pond 65 is 16.6 m, with a maximum depth of 57.8 m. Water clarity was high with Secchi disk measurements averaging 5 m. Field pH was 6.49-6.98. TDS ranged from 4-38 mg/L. Hardness, nutrients and specific conductance were all very low, indicating oligotrophic conditions with primary production co-limited by nitrogen and phosphorus. In July, a thermocline was developing between 3-8 m. In September, a pronounced thermocline was present at 12-14 m.
Probable Surface Water - Groundwater Relationships
Groundwater samples were not collected in the Pond 65 Watershed; therefore
the surface water-groundwater relationship is inferred. Station 16 is located
at the discharge of Pond 65. This sample location is also at the point
of discharge to Kangeklualuk Bay. The concentration of the major ions (sodium,
calcium, bicarbonate, and sulphate) in the water at this location was within
the range of values reported for Station 21 on the northwest corner of
Kangeklualuk Bay. The pH and TDS concentrations were also similar to values
reported for Station 21. The area is dominated by surface runoff. Groundwater
discharge is projected to be a relatively small component of the overall
streamflow.
10.1.5.5 Kangeklukuluk Bay Drainage
Option 5 Watershed
Hydrology
Option 5 watershed drains an area of about 14 km2 from west to east. This fjord-type valley watershed is composed of four ponds which drain to Kangeklukuluk Bay. It is similar to the Camp Brook subwatershed with large wooded areas and draining similar elevations. Spot flow measurements and runoff observations in this basin showed similar patterns to the Camp Brook subwatershed, as expected. This watershed is considered to have good dilution capacity.
Hydrological data and baseline chemistry data have been collected from Pond 58 (Option 5 Pond) and Stream 22 within this watershed.
Surface Water Chemistry
The average depth of Pond 58 is 13.1 m, with a maximum depth of 34.2 m. Secchi disk measurements averaged 7 m. Field pH values ranged from 6.16-6.85, with the top three pH measurements being slightly higher in September than July. Hardness, nutrients and specific conductance were all very low, indicating oligotrophic conditions. In July, the top 4 m were warmer than at depth but a thermocline had not been established. In September, a thermocline was present at 11-13 m.
The pH of samples collected downstream of Pond 58 ranged from 6.5-6.8. Nitrate and orthophosphate concentrations were below LOQ, indicating that primary production was co-limited.
Groundwater Chemistry
Similar to the groundwater within the proposed North Tailings Basin area, the overburden and bedrock groundwater in Option 5 was weakly mineralised, with TDS concentrations of 71-119 mg/L. The pH was near neutral, between 7.1-7.3, however one sample was alkaline, with a pH of 9.0. This single value may be an artifact of the mud used in drilling the monitoring well.
The major dissolved constituents of the groundwater included sodium (4.0-42.9 mg/L), calcium (1.0-17.7 mg/L), bicarbonate (32-69 mg/L as CaCO3) and sulphate (5-38 mg/L). Chloride concentrations were uniformly low (less than 1-2.4 mg/L). Concentrations of potassium (1.3-2.3 mg/L) and magnesium (0.4-2.7 mg/L) in the groundwater were also typically low. Overall, the groundwater had a sodium-calcium-bicarbonate composition.
With respect to trace metal composition, the groundwater contained traces of aluminum (0.044-0.49 mg/L) and iron (0.03-0.40 mg/L), which is typical of water in siliceous to mafic crystalline bedrock terrain. Copper concentrations were less than 0.002-0.006 mg/L. Concentrations of nickel were between less than 0.002 and 0.011 mg/L. Concentration of the remaining heavy metals in groundwater were generally below the LOQ.
Surface Water - Groundwater Relationships
The water discharging from Pond 58 (Station 22), which is representative of the pond water, was very weakly mineralised with TDS concentrations of 13-22 mg/L, and an average TDS concentration of 16 mg/L, which was typically about 6 times less than that of groundwater in this area. The pH of the water was slightly acidic between 6.5-6.8. The average calcium concentration in the surface water at this location was 1.8 mg/L compared to average groundwater concentrations of 9 mg/L. Similarly, average sodium concentrations (1.5 mg/L) in the surface water were much less than that of groundwater (2 mg/L). The major anions in the surface water were bicarbonate (4-5 mg/L) and sulphate (3-10 mg/L), which occurred at approximately 3-7 times less than groundwater concentrations.
Pond 67 Watershed
Hydrology
The Pond 67 watershed drains an area of about 8 km2 . This watershed has similar physiographic characteristics to Camp Pond with a high percentage of wooded area and with some barren areas at the higher elevations. The large pond in the watershed and possible natural regulation suggests that the runoff pattern may be similar to that of the Camp Brook subwatershed.
Surface Water Chemistry
Pond 67 was sampled once in September 1996. Field pH ranged from 6.69 (deep sample) to 7.6 (surface). TDS ranged from 20-25 mg/L. Hardness, nutrients (nitrate, ammonia and phosphorus) and specific conductance were all very low, indicating oligotrophic conditions. In September, a thermocline was present at 10-11 m depth.
The pH of samples collected downstream of Pond 67 (Station 35) were 6.7-6.9. Nutrients (nitrogen and phosphorus) were measured at concentrations below LOQ, indicating co-limitation of primary production. Low hardness indicated a low buffering capacity.
Probable Surface Water - Groundwater Relationships
Station 35 is located on a separate stream which also drains to Kangeklukuluk Bay. The water quality reported for this location was similar to that of Station 22. Groundwater samples were not collected in the vicinity of Pond 67; however, the groundwater quality in the vicinity of Pond 58 is likely representative of groundwater throughout this watershed.
The surface water quality from this area indicated that the water is
largely derived from surface runoff, with limited influence from groundwater
discharge. The composition of the dissolved constituents in the surface
water (calcium bicarbonate water) suggested that most of the groundwater
discharge to the surface water is derived from the shallow, relatively
more permeable overburden and weathered bedrock.
Hydrology
The Throat Bay watershed drains an area of about 35 km2. This watershed has similar physiographic characteristics to Camp Pond with a high percentage of wooded area and some barren area at the higher elevations. Spot flow measurements in this basin showed similar patterns to other gauged rivers in the Assessment Area. There are a large number of ponds in the watershed and possible natural regulation suggesting that the runoff pattern may be similar to that of the Camp Brook subwatershed.
Surface Water Quality
On average, the results were consistent with the other watersheds in the area, being slightly acidic and having low nutrient levels and trace metals (Tables 10.4 and 10.5). TDS ranged from 10-40 mg/L.
Probable Surface Water - Groundwater Relationships
Groundwater samples were not collected in the Throat Bay watershed.
However, the general groundwater influence on surface water quality can
be inferred from surface water quality data. Surface water samples were
collected upstream and downstream of Pond 70, at Stations 43 and 39, and
at the outlet to Throat Bay (Station 40). There was little variation in
water quality at the upstream locations and downstream Station 40. The
water was weakly mineralized with concentrations of major ions typically
less than that of groundwater. This water quality data was similar to that
of other watersheds where streamflow is dominated by surface runoff and
groundwater discharge is a relatively small component of the overall flow.
10.1.5.7 Anaktalak Bay Drainage
Little Reid Brook Watershed
Little Reid Brook discharges into Edward's Cove, draining approximately 15 km2 (Figure 10.1). The proposed main access road from the port to the mine/mill is located in the Little Reid Brook valley. The areas drained are generally sheltered and wooded, although the upper levels are rugged and barren, particularly to the west.
Hydrology
Spot flow measurements recorded upstream of the outlet of Little Reid Brook showed that this watershed has a similar response as the Camp Brook subwatershed, due to the sheltered wooded terrain and near sea level elevation. Little Reid Brook upstream of the outlet to Anaktalak Bay is flat and meandering and is subject to tidal intrusion (marine waters) from Anaktalak Bay.
Surface Water Chemistry
Two surface water quality sampling stations (Stations 11 and 12) were established along the main channel of Little Reid Brook, which flows northward into Edward's Cove and Anaktalak Bay. There are no ponds within this watershed. Water quality sampling on this stream indicated a range in pH from 6.2-7.3. TDS ranged from 8-36 mg/L. Nutrient concentrations were low, indicating that nitrogen and phosphorus co-limited primary production. Low hardness is indicative of the low buffering capacity of the surface water. High TSS, which contribute to elevated total metals, were noted in this drainage.
Groundwater Chemistry
The area is underlain by extensive alluvial deposits of sand to sand-and-gravel that are typical of a significant fresh water aquifer within this area. Groundwater was obtained from an existing water supply well. This soft water was characterised by a measured TDS of 57 mg/L and a near neutral pH of 6.9-7.3. The principal dissolved components within the water were calcium, sodium and bicarbonate. The water contained slightly elevated iron (0.25-0.40 mg/L). Copper (0.004-0.016 mg/L) and zinc (0.015-0.13 mg/L) were generally elevated.
Surface Water - Groundwater Relationships
Little Reid Brook appears to receive a significant component of groundwater baseflow, which apparently increases downstream between stations Stations 11 and 12. The TDS of the upstream sample location (Station 11) varied between 13 and 45 mg/L while downstream the TDS was higher, varying between 24 and 58 mg/L. This relative increase in TDS is attributed to contributions from groundwater baseflow. This was also evident in the doubling of the average alkalinity from 6.5-14.4 mg/L downstream. The water from Stations 11 and 12 also contained minor concentrations of sulphate averaging 2.5 and 3.6 mg/L, respectively, whereas chloride was low, averaging 1.2 and 4.7 mg/L, respectively.
Calcium and sodium were the main dissolved cations in the water, with average calcium concentrations increasing from 1.8 mg/L upstream to 3.4 mg/L downstream and average sodium concentrations increasing downstream from 1.3-4.5 mg/L. The increases were consistent with downstream increases in groundwater discharge. Calcium and sodium occured at near equal concentrations, indicating that most of the contributing groundwater is from the surficial alluvial aquifer, with little influence of sodium dominated bedrock groundwater.
In one sampling event, the downstream water sample from Station 12 recorded elevated sodium (15 mg/L) and chloride (20 mg/L) concentrations with no associated increase in calcium (3.6 mg/L) and bicarbonate (11 mg/L). These results are probably due to the influence of seawater, likely carried inland by rain and sea spray during storms.
The stream water had elevated concentrations of aluminum (0.026-1.04 mg/L) and iron (0.05-1.08 mg/L). These concentrations were typical of background conditions for the terrain. Trace levels of copper (up to 0.037 mg/L) were occasionally encountered in the stream water at Station 12. The source of the trace levels of copper could be the disseminated copper sulphide mineralization exposed at an hilltop outcrop at the eastern headwater of the stream.
In summary, the surface water draining from Little Reid Brook is more
heavily influenced by groundwater discharge, as noted by the TDS and alkalinity,
compared to the other watersheds of similar or larger size within the Assessment
Area. This is due to the extensive surficial deposits of sand and gravel
within Little Reid Brook that appear to form the only significant aquifer
within the Assessment Area.
10.1.6 Likely Future Conditions
The water quality in the Assessment Area is dominated by surficial and bedrock geology and climatic conditions. The existing natural water quality environment has taken thousands of years to develop. These conditions have developed as a result of natural weathering and erosional processes. Projected long term changes in climate (e.g., global warming or cooling, increased variability in weather, and an increase in sea level) are unlikely to influence water quality in any measurable way with the exception of decreases or increases in acid rain. The water quality within the Assessment Area, within the expected lifespan of the Project, in the absence of Project activities, is expected to remain unchanged.
