Martin Brook Fisheries Enhancement
This area was a real challange to the Bilston Watershed Habitat Protection Association. Here the B.C. Ministry of Highways had literally blown away a rock slope to provide material to widen the highway to Sooke from Victoria and then dug a channel through the remaining debris to create a channel for the stream, Martin Brook, which is a major tributary to Bilston Creek, to flow through. With the Ministry of Environment's help, Highways had constructed a small dam at the upstream, (west), end of the site, as a flood water control device. The problem here was that during the dry season the pond behind the dam would dry up and any fish trapped there were doomed. Surveys showed however that the area upstream from the dam provided a large spawning area for trout which would move downstream as the water levels fell. The dam however tended more to trap fish as the water would leach through the broken rock rather than be contained for the summer or flow over the dam.
To solve this problem the "B.W.H.P.A." in conjunction with the Ministry of Highways, Ministry of the Environment, Municipality of Langford and the Victoria Capitol Regional District, as well as many volunteers from local businesses and interested groups developed a plan to replace the dam with a structure more suitable to holding water during dry periods as well as methods to encourage native plant growth along the now exposed waterway to provide shade and reduce evaporation.
The first thing was to deepen the pond and rebuild the dam to be more impervious. This was started during August so the water was very low. In fact there was no water downstream from the dam for 200 meters. The pond itself was only about one meter deep at the most. The flow in was blocked off with netting so no fish could move down into the pond and then all the fish in the pond were carefully netted and moved to other areas of the stream. Next all the water was pumped out and most of the water plants removed and stored to be replanted later.
The excavator now dug the pond out about two meters deeper and somewhat wider. This material was a fine peat soil which was saved to use for planting in the rocky banks below the dam. The old dam was removed and, as suspected, was found to consist of only rock and sandy gravel. No surprise the water leaked through so fast. We rebuilt this using clay and soil and then faced it with filter cloth. The whole structure was then covered with broken rock to protect it from damage during periods of flood and high water velocities. Unfortunately, the dam joins up to the base laid for the Highway beside here. This material is not as impervious as the new dam and some water leakage was expected.
Below the dam, the old channel was deepened, down to and into the bedrock. A number of boulders about a meter in diameter were placed in the channel and gravelly material laid between. This resulted in a number of pools and riffles for the length of the site. In the pond was placed a couple of waterlogged stumps and two partly submerged logs. For the trout these will provide hiding places from predators and sunlight, and insects will live in the wood and become fish food.
Over a period of several weeks, the banks of the stream and the new larger pond were replanted with native shrubs, trees, and water plants. The upper bank out to about eight meters from the stream was planted with trees, such as pine, which grow in similair areas hereabouts. On the slope dropping to the channel, was placed wild rose, salmon berry, red osier dogwood, and other similair sized shrubs. Next to the water level was placed water reeds, rushes, and many of the plants salvaged from the excavation work.
The next spring trout were observed spawning in the new channel, and shortly after fingerlings were moving about in the small pools. As the weather warmed and the water levels dropped we were concerned that the fry might get trapped in remnant pools and die in the summer heat. In fact most appeared to move downstream to areas of constant flow. A last few fish did have to be trapped and moved but overall an increase in numbers was indicated. The pond has remained at a higher level all summer so even though we still have some leakage the overall effect has been very positive.
This next summer some more gravel suitable for spawning was placed into the channel in selected spots. Most of the shrubs and trees have been growing well and some shade is now being produced.