Water Stewardship Information Sources
| Citation | Greenbank Environmental Inc. 2012. Alouette Project Water Use Plan: Allouette Water Temperature, Implementation Year 5. BC Hydro. |
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| Organization | BC Hydro |
| URL | https://www.bchydro.com/content/dam/BCHydro/customer-portal/documents/corporate/environment-sustainability/water-use-planning/lower-mainland/alumon-5-yr5-2014-06-02.pdf |
| Abstract/Description or Keywords | Water temperature in the Alouette River downstream of the Alouette Dam continues to be a concern for BC Hydro, environmental agencies and stakeholders. To address these uncertainties, BC Hydro has commissioned a monitoring program to measure water temperatures at various locations in the watershed to assess the risk of a high temperature event capable of impacting fish populations, as well as explore feasible operational changes that can be taken to mitigate such impacts. This Year 5 report summarizes the 2012 temperature data and provides comparisons to earlier years. Water temperatures in the plunge pool immediately downstream of the Alouette Dam ranged from a low of about 4°C in December through to January, rising temperature conditions from February onwards with peak temperatures occurring in late August and early September, and declining temperatures for the remainder of the year. At no time did daily average water temperature reach lethal levels for salmonids. Water temperatures typically reached summer highs of 19°C to 22°C during the 2000 - 2010 monitoring period, while temperatures in 2012 did not surpass 18°C. Daily mean water temperature reached its seasonal maximum at the beginning of September where it approached 17°C at the Plunge Pool site. Plunge pool temperatures were found to be similar to that measured in the vicinity of the LLO intake in the reservoir, suggesting that inflows to the intake were selective to a narrow layer of water just above the intake structure. The only exception was during the spring surface release operation starting in April and ending in June, where plunge pool temperatures were more similar to reservoir surface water temperature. Plunge pool temperatures remained largely unchanged while traveling to the Mud Creek site downstream. Some evidence of cooling was found, but it was believed to be due to a miss-calibrated temperature logger rather that a geomorphological event. As water travelled further downstream, there was a tendency for it warm slightly during spring, cool when mud Creek temperatures began to exceed 15 °C in mid to late summer, and cool more quickly later in the fall. The general tendency was for peak temperatures seen at the plunge pool to attenuate as it traveled downstream, becoming roughly 1°C cooler at 224th Street Bridge, and with a seasonal peak temperature arriving two weeks earlier. Overall, preliminary indications suggest that the WUP operations at Alouette Dam has had a positive effect on river temperatures, warming sooner in spring and early summer (due in part to surface releases) and cooling sooner in mid to late summer when compared to LLO releases alone. This was seen as a positive effect on salmonid ecology and production. |
| Information Type | report |
| Regional Watershed | Lower Fraser |
| Sub-watershed if known | Alouette River |
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| Comments | |
| Project status | complete |
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