J. Hillaby & E. Gruhs
Background:
No stream survey is complete without looking at multiple sites along the mainstem, and Dillabough Creek is a case in point. While it looks entirely pristine, there’s history here. The upper reaches include some fine fishin’ lakes, there’s old and new logging, old fires, some hayfields and private property, and in the lower reaches it is encompassed by the Horsefly Lake Provincial Park and a crossing under the Z road. Our purpose today was to see what, if any, water quality differences could be detected from bottom to top.
Take home messages:
First, we took a good look at the clarity and colour of the water at the lower end, just above the culvert at the Z road crossing. The two samples are virtually identical, comparing Dillabough Creek water (right) with commercially filtered bottled water (left).
Last week we went upstream about 1 km, at the base of the falls, the creek water was clear but noticeably tea-coloured. No photos, sorry.
Further upstream today at the Nikwit Lake outlet culvert, the pool immediately downstream of the culvert was noticeably cloudy. We measured this at 15 JTUs (Jackson Turbidity Units). Note that this tester puts a rough number on turbidity but further analysis would be required to translate this number into a specific biological effect.
Just upstream of the Nikwit Lake culvert, there was some standing water with very little flow passing through the culvert. It was stagnant ( dissolved oxygen at 34% saturation), clear and slightly tea-coloured.
Near the Nikwit Lake boat launch, in the stream channel about 100m upstream, the water is now sub-surface. There is a 30 year old (?) structure that is today completely blocking all surface flow.
Next Steps:
We will come back to Dillabough in the spring and see these same sites under high water conditions.
Next Thursday, September 23, 2021 we will tackle the mainstem Horsefly. The objective will be to locate spawning salmon and have a close look at sockeye and hopefully pink carcasses. We will visit up to three sites, bring your boots and be outside SAWS at 1 pm.