Speckled dace (Rhinichthys osculus) COSEWIC assessment and status report: chapter 5
Habitat
Habitat requirements
Available information on habitat is based on seasonal observations, but only during daylight hours, nocturnal use of habitat has not been described. Speckled dace habitat in the Kettle River during spring, late summer and fall has been described as follows (Peden and Hughes 1981, 1984; Peden 1994, 2002): in general, dace were collected on the bottom in rocky substrates with riffles and slow to relatively fast water velocities depending on fish size. In March they are likely exhibiting overwintering behaviour due to low water temperatures. At this time of year they have been found in relatively deep water (>1.0 m) runs behind structures such as large rocks, logs and bridge abutments.
The following observations were made during the summer-fall period. Concentrations of young-of-the-year (age 0+) dace were found along the river edge in shallow, low velocity habitat where they were observed in clean cobble substrates with ample interstitial spaces (clean spaces between the stones) that appeared to offer cover from predators. Adult R. osculus (> 40 mm SL) appear to be associated with larger substrates and swifter currents. Adults were found immediately above Cascade Falls in boulder substrate (30-40 cm diameter). Large particles are characteristic of steep riffles, rapids and cascades (which are uncommon in the system, particularly in the low gradient reaches of the mainstem rivers). Flushing flows would be required to maintain interstitial spaces in this type of habitat. No large concentrations of speckled dace were found in the lower Granby River, where bottom substrates were predominantly sand, although some fry were found in this area in the early 1980s. Most of the adults found were located in the section of the river between the highway bridge crossing at Grand Forks and the confluence with the Kettle River. The authors reported that large speckled dace were most frequently observed in water depths >0.5 m. Water deeper than 1.5 m was not sampled, but Peden (2002) speculated that speckled dace do occur at greater depths. Speckled dace were more abundant in areas where only a thin film of algae occurred on the rocks than where algae growth was thick.
Recently speckled dace were collected in the spring and fall in side channels and in edge habitat upstream of the Kettle River canyon (located southwest of Christina Lake, the canyon (Figure 4) is 900 m long and lies immediately below Cascade Falls) [PDI 2005]. The data indicated that juvenile speckled dace used side channel habitat throughout the year, and edge habitat during the spring and fall, while adult speckled dace utilized shallow water habitat primarily during the summer, in years of low flow side channel and edge habitat would not be available and the fish would be confined to shallow water. In periods of severe drought dace would be isolated in areas of whatever shallow areas remained or perish. Very few speckled dace were collected from similar habitat below the canyon. During October (2005) snorkeling surveys, speckled dace were observed in riffles or other fast water areas (A. Wilson pers. comm.).
Figure 4. Canyon below Cascade falls,Kettle River [photograph from Okanagan Nation Alliance presentation to Powerhouse Energy Corporation, September, 1999 (EAO 1999)].
Figure 5. Summary of daily discharge for the Kettle River showing the 2003 drought year against the average daily maximum, minimum, and the upper and lower 25%. Flows in September 2003 were the lowest experienced over the 75 year period of record.
Figure 6. Late summer base flows at Laurier, Kettle River, showing the recurrence interval of instream flows below standard fish conservation flows of 10% and 20% MAD. The extreme low (September 2003) was 5% MAD and well below recognized fish conservation levels. The dashed line represents the recurrence interval of a Mean Monthly discharge of 10 cms.
Peden and Hughes (1981) found juvenile speckled dace throughout most of the Kettle River below 884 m in elevation in appropriate habitat. They noted that smaller fish tended to occur higher up in the system than larger fish, which they attributed to different opportunities for growth related to temperature conditions. Delayed spawning at lower temperatures may also be a factor. The authors noted that the comparatively smaller size range in the Granby River may indicate a less productive river.
Haas (2001) tested water velocity preferences for mature speckled, leopard and Umatilla dace in the field, during the low flow period in the fall, and velocity tolerances for mature speckled dace (50 to 70 mm size range) under laboratory conditions (at 18ºC). Field data were collected in the mainstem Kettle River and the Granby River. In the wild, Haas (2001) found speckled dace at the lowest water velocities. On the bottom of the stream (where speckled dace were found) water velocity ranged from 0 to 15 cm/sec (median velocity ~ 3 cm/sec) compared with 0 to 30 cm/sec (median of 15 cm/sec) at 60% mean depth. In the lab, Haas (2001) found that speckled dace tolerate the lowest velocities of all three dace species at a maximum of about 60 cm/sec (at both the bottom and 60% mean depth). The median depth preference for speckled dace was about 30 cm (range of 5 to 65 cm) in the wild. Sampling was limited to the maximum depth attainable wearing chest waders. For larger dace it is possible that the depth preference was biased by the difficulty of sampling in deeper water or that variations in substrate size influenced the results. Only very small speckled dace were found along the stream margins. In early August, fry (about 10 mm long) can be dip-netted from shallow (<2 cm) still water over silt or sand substrates (McPhail undated).
Depth and water velocity preferences (HSI curves/Habitat Suitability Index curves) in the wild likely vary between systems depending on habitat availability, water temperature, food supply, fish size, abundance and the other fish species present (Baltz et al. 1982; Moyle and Baltz 1985). HSI curves developed by Moyle and Baltz (1985) for Deer Creek, California (mean annual stream discharge (MAD) of 9.096 m³/s, a much smaller stream than the Kettle River) indicate a preference for habitat with a water column water velocity of <70 cm/sec (mean <29 cm/sec) with water depths of 5 to 65 cm for juveniles (mean 27 cm); and velocity of <120 cm/sec (mean <44 cm/sec) and water depths from 5 to 75 cm (mean 27 cm) for adult speckled dace. Speckled dace were found most often in larger substrates, primarily cobble and boulder. HSI curves, however, can be biased by stream-specific hydraulic diversity and stream size.
MAD for the Kettle River at Cascade is about 75 m³/s (Powerhouse Energy Corp. 1999). Annual flow patterns in the Kettle River system are similar to most interior streams with high flows in spring under snowmelt conditions (May to July) and low flows during the fall-winter period (October through March). Peden (2002) observed evidence of the extent of peak flows in flood debris caught in trees 6 m above fall water levels near Cascade (an area where the channel is confined by a bedrock canyon).
Water Survey of Canada temperature records for the Kettle River near Ferry (USA), downstream of Midway BC, suggest a mean annual water temperature of about 8ºC and a maximum temperature of 23ºC. Low water temperatures (<5ºC) occur during the November to March period. Water temperatures during summer are cooler in the tributaries than in the mainstem rivers. In August water temperatures in two tributaries averaged around 13-15ºC compared with 19-20ºC in the mainstem Kettle and West Kettle rivers; in September temperatures in seven tributaries ranged from 8-12ºC while averaging 12 and 14°C in the Kettle and West Kettle rivers (Sebastian 1989). Oliver (2002) reported maximum daily temperatures during the summer of 23°C at Midway, 24°C at Grand Forks and 25°C at Cascade. Cool water temperature may limit distribution within the system by preventing the use of tributaries. Sebastian (1989) did find dace in one tributary, Rock Creek, immediately above the confluence with the Kettle River. More recent surveys of the Kettle River, including Rock Creek, did not find dace in four major tributaries of the Kettle River (A. Wilson pers. comm.).
Most of the year water clarity is high. BC Ministry of Environment water quality data for September, 1988, suggested a moderately productive system with total alkalinity in the range of 50-65 mg/L and total dissolved solids of 80-116 mg/L for the Kettle and West Kettle rivers; pH ranged from 7.9 near Midway to 7.4 in the headwaters for the Kettle River (Sebastian 1989). Environment Canada (2005) website data for Kettle River at Carson Road Bridge indicates similar total alkalinity levels during the summer months over the period of record. In October of 2005 alkalinity ranged from 78 to 82 mg/L and 46.5 to 77.9 in the Kettle. Total phosphorus was below the detectable limit (0.002 mg/L) except in the Cascade Canyon where it was slightly above (0.003 mg/L), while total nitrogen ranged from 0.06 mg/L in upstream areas to 0.24 mg/L at the Cascade Canyon, and nitrate from 0.011 mg/L to 0.115 (Wilson pers. comm). This illustrates high annual variability of water chemistry correlated with changes in stream flow. Flow analyses demonstrated that stream discharge is particularly limiting in late summer (Sebastian 1989) for aquatic species. The Kettle-Granby system was a strong candidate for “sensitive stream” designation under the BC Fish Protection Act (1997) because summer flows are substandard for fish requirements with prolonged, dewatered habitats in some streams (B.C. Ministry of Environment unpubl. data).
Habitat trends
Trends in the availability of suitable habitat can be inferred from patterns of human activity in the watershed. Information on the area is available on the Regional District of Kootenay Boundary (2003) and City of Grand Forks (2005) web sites.
The first Europeans to settle the area were farmers, but around the turn of the 20th century an industrial boom occurred that included the construction of railroads, mines, a smelter and a power plant. Slag piles and remnants of the smelter can still be seen near town. Today, the economy of Grand Forks is based on the lumber industry, although agriculture, mining and tourism are also important contributors. The population of Grand Forks has grown from about 200 in the mid-1890s to around 4,000 today (currently about 10,000 in the Kettle-Granby basin or Kootenay Boundary area).
Significant water withdrawals for agricultural purposes, particularly for irrigation, have an impact on habitat availability during the summer months when flows are already naturally low. Aqua Factor Consulting Inc. (2004) analyzed demand and water availability in the Kettle River basin. Irrigation accounts for between 75 and 85% of total demand. Low flows have worsened in the last 75 years, partly due to the increase in water allocations, to a point where the system is now considered ‘regulated’ (the system is considered regulated, rather than natural, due to the amount of water being withdrawn from the system as the result of diversionary structures and run-of-the-river withdrawals) (R.A. Ptolemy). In the BC portion of the watershed above Cascade, the rate of growth in the area of land under irrigation licences increased gradually from about 5 to over 160 acres/year between 1929 and 1962; between 1963 and 1981 the area under irrigation grew at an average rate of 585 acres/year then declined at an average rate of 65 acres/year as water users in the basin switched from diverting surface water to using groundwater (Aqua Factor Consulting Inc. 2004). There appears to be a strong linkage between the aquifers and the flow in the mainstem rivers, and the switch to groundwater sources may not resolve the chronic low flow problems in the system. The growth in use of groundwater cannot be determined since a licence to use groundwater is not required in BC. Surface water withdrawals of about 60,000 acre-feet/year are licensed from BC and Washington combined; much of the demand is in the summer-fall period, and most licences are unsupported by storage. In Washington, which requires a licence for removal of groundwater, an additional ~ 9,000 acre-feet/annum has been allocated for this purpose. The licensed water allocations are about twice the amount taken during 2003. Aqua Factor Consulting Inc. (2004) estimates that the unused portion of the water allocation may be sufficient to supply the increase in demand over the next 30 to 40 years.
Peden and Hughes (1981) reported low fish abundance, including speckled dace, in the Kettle River near the lumber mill at Midway, and an absence of speckled dace immediately downstream from the sewage treatment plant at Grand Forks (at the junction of the Kettle and Granby rivers), possibly due to changes in water quality. These human activities may have affected fish abundance and probably continue to have impacts (Peden 2002). The empirical data may also be an artifact of low stream gradient and the lack of steep riffles in these two sections.
A proposal to develop a run-of-river hydroelectric generation project at Cascade Falls, downstream of Grand Forks, was submitted to the provincial government in 1999. (A run-of-river project does not require a large reservoir to store water inflow from the catchment area, asthe river flow and vertical drop provide the pressure to turn the turbine; it does require a diversion of water to the turbine.) Cascade Falls is located in the middle of the Kettle River canyon.If it proceeds, this project will be built on the historic site of an abandoned power station, which was constructed in 1899 and operated until 1919. After an analysis of fish habitat impacts based on the initial proposal at a weir crest elevation of 485.5 m, the company brought forward a second proposal (PDI 2003). This proposal lowered the weir crest elevation to 483.2 m and incorporated a rubber dam. This design change significantly reduces the impoundment area and allows for the passage of bed load through the system, they have been utilized with success elsewhere in the province for small or micro-hydro projects (B.C. Hydro 2000). At a mean annual discharge of 75 m³/s the proposed backwater effect has been reduced to 750 m (compared to 1.7 km under the original weir height proposal). At the lower weir crest height the water surface elevation at the weir is projected to be 0.7 m higher than under natural conditions and mean annual flow and 1.1 m higher than under natural conditions at a reduced flow of 10 m³/s. The footprint of the weir will result in the loss of 537.5 m² of potential speckled dace habitat (PDI 2005). The weir, however, is located in an area considered to be marginal habitat as speckled dace could be susceptible to flushing downstream over the falls and lost to the population.
The canyon is only 900 m long and lies immediately below the weir site. The distance from the lower end of the canyon to the USA border is 5 km. Potential impacts below the flow return point in the powerhouse tailrace are nil. This is because generation flows are combined with assured canyon flows to equal the natural flow at the upstream end of the lower 5 km section. According to the fisheries technical reviewers (see for example EAO 2004) of the Cascade Project the chances for dewatering are nil even though there is a small chance of a short flow disruption through stalled flow routing with power outages, basically because flow disruptions due to rerouting back through the natural channel will not last long enough for dewatering to occur. Peden (2001) indicates that the population below the falls does not appear to be self-sustaining, which may be due to reproductive isolation or competition with Umatilla dace.
Although the proponent recognizes that there is a level of uncertainty in predicting the response of speckled dace to creation of the head-pond, they have discussed project changes with Dr. J.D. McPhail (UBC) and Dr. Alex Peden, both academics with expertise in BC dace (PDI 2005). The results of HEC-RAS modeling [hydraulic modeling of depth-velocity changes at different flows and backwater effects (US. Geological Survey 2004)]have been discussed with Dr. J.D. McPhail and have been reviewed by both federal and provincial fisheries agencies as part of the ongoing environmental assessment process. McPhail and Peden (PDI 2005) have indicated that impacts to speckled dace habitat may not be significant under the new configuration. Mitigating reasons include: important areas including possible spawning habitat and areas where the highest densities of speckled dace have been found are located upstream of the backwater area; the head-pond will remain flowing; and the weir can be deflated during high flows to allow flushing of any fine sediment accumulations from the head-pond area. More recently (Bradford 2006), an allowable harm assessment report indicates that only a small fraction of the speckled dace population would be affected by the project because of the small impact of the headpond and the facility operation, and concluded that the proposed project would, at most, represent nothing other than a very minor increment in the risk of extinction. In response to the uncertainty, a monitoring plan has been proposed as part of a compensation program to assess any changes to speckled dace habitat, abundance and entrainment, if the project proceeds (PDI 2005).
Habitat protection/Ownership
Known speckled dace habitat receives general protection under federal legislation, such as the fish habitat section of the Federal Fisheries Act, and habitat related provisions of various provincial statutes designed to protect the environment, water quality and fish. None of this legislation specifically protects speckled dace habitat. In addition to these broad protection measures, speckled dace habitat receives consideration by both the provincial and federal government (e.g. under environmental assessment procedures) due to its recognition by the BC Conservation Data Centre and COSEWIC as a species at risk.
The Kettle River has been designated a Heritage River by the provincial government as part of British Columbia’s Heritage Rivers System in recognition of its outstanding natural, cultural and recreational values. The main objective of the Heritage Rivers System is to raise awareness and promote good stewardship of BC’s rivers. The management guidelines for the river are: to protect habitat for rare fish species; to establish and maintain an integrated sustainable approach to land and water use within the watershed, with specific consideration for the agriculture industry; to protect and monitor the health of natural processes in the river; and to manage and monitor recreational use so as to maintain the quality of the experience with minimal environmental impact. Once a river is designated, the vision and management guidelines for the river are considered in planning processes; however, while they are intended to guide the process they do not dictate the outcome.
The waters inhabited by speckled dace in Canada are owned by the crown; however, the private use of surface water is licensed.