CHILLIWACK, B.C. – Fisheries and Oceans Canada says work on a Trans Mountain pipeline crossing in a British Columbia stream altered habitat for young salmon, but the creek will return to normal in one to two years.Two biologists with the department visited Stewart Creek in Chilliwack after receiving a complaint from Mike Pearson, a biologist with 30 years of experience.Pearson says the placement of 17 metres of concrete at the bottom of the stream has reduced hiding places for coho and chum salmon and inhibited growth of the invertebrates they eat. The Fisheries Department says the stream bed has been altered from soft sediment to hard substrate, but the natural accumulation of sediment will help re-establish pre-existing conditions.December 20, 2018. Immediately downstream of the TMPL ROW during a post-construction site inspection showing high water levels have reached the delineated high water mark. Sustained conditions such as these will lead to further accumulation of native substrate by natural recruitment – Trans MountainIt also says there are unlikely to have been impacts to salmon from the temporary alteration because similar rearing habitat exists upstream and downstream of the site.Trans Mountain says it agrees with the assessment by the Fisheries Department and it relies on highly qualified professionals to design and implement crossings.