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Spawning gravel quality within the Coquitlam River: potential impacts from gravel pit mining

University of British Columbia

Potential spawning sites within the Coquitlam River were evaluated for their ability to support embryos through to the late stages of incubation. Freeze core samples were collected from four sites beginning on December 18, 1997 through to April 14, 1998. Dissolved oxygen and relative permeability data was collected from March 28, 1998 through to April 14, 1998. Sediment traps were also placed at the four sampling locations on March 20, 1998 and removed May 4, 1998 (45 days). Two of the four sites had descriptive measures (%<0.85 mm, dissolved oxygen, and Fredle index values) that classified them as 'good' quality spawning habitat. The other two sites had descriptive measures reflective of'poor' quality spawning habitat. Of the two 'poor' quality habitats, one was exposed to episodic upstream slides that were believed to be depositing fines within potential spawning gravel. The other site was directly downstream of discharge effluent from gravel mining. The impact from the gravel mining appeared to be localized. A site approximately 1.5 km downstream had 'good' quality spawning habitat whereas a sample site 0.3 km downstream had 'poor' spawning habitat. In addition, sediment trap data showed a significantly finer distribution of deposited material immediately downstream of the gravel mining outfall. Approximately 1.5 km downstream the deposited material had a significantly coarser distribution. Although it appeared that the gravel effluent was affecting gravel quality locally, attempts to trace the deposited material to the source was not successful.

Thesis/Dissertation

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2009-05-26

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http://hdl.handle.net/2429/8297

Civil Engineering

University of British Columbia

UBCV

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