Why a B.C. group is asking you not to build rock dams in our rivers and streams

If you’ve ever been tempted move rocks in your local river to create a little dam or pool, a streamkeeper’s group is telling you not to do it.

It may feel harmless at the time, but the Pacific Streamkeepers Federation says these human-made rock formations can have some pretty big consequences, especially with salmon spawning season approaching.

For one, ZoAnne Morten, executive director of the federation, says you could be interfering with salmon on a variety of levels.

“First off, you’re moving their home, right? So those rocks, they hide in amongst them and that’s their home, and they’ve had their own little spot — they work really hard to find a little spot that’s their own — and then, if someone moves the rock, it might be the rock they were hiding underneath of. So that’s gone,” Morten explained.

“When you’re walking around in the stream, you’re actually walking on the rocks and there are fish right below your feet. When you get in the water, the fish go down, they hide on you and and they go in amongst those rocks. And so one, you’re picking the rocks off and exposing them, taking their house apart, and the other one is you’re stepping on them.”

Moving rocks also disrupts bug habitats, Morten explains, noting bugs live under rocks, move above them to feed, and then return below to hide.

These bugs are often food for the salmon.

“These are things people don’t think about,” Morten told 1130 NewsRadio.

‘Everyone loves the salmon’

On a bigger scale, Morten says building mini dams to create pools can increase the temperature in the water.

“Hot water doesn’t hold oxygen,” she said. “So, while people sometimes think, ‘Oh, look at that, I made a great place for these fish, I made a pool for them,’ you’ve actually made an area with warmer water with less oxygen in it that’s always full of creatures.”

Pool areas also make it easier for prey above the water to spot salmon, Morten adds.

She doesn’t believe people mean to be disruptive, noting, “anyone you talk to … they love salmon, everyone loves the salmon.”

“People think it’s not much, but people who are out for the day, they don’t really understand how good they are at moving stuff. They don’t understand. They think, ‘I’m just going to go out here and move a few rocks.’ But when they look back at what they’ve done, they’ve actually done quite the Great Wall of China. You’ve seen some of these structures, and go like, wow, that’s kind of amazing.”