The BNSF Railway has been fined $75,000 for damaging fish habitat in Delta's Cougar Creek in the fall of 2010.
Rail line maintenance work conducted by the company deviated from the work plan and area mapped out by its environmental consultants, according to the Department of Fisheries and Oceans.
Crews also used more than twice as much rip rap rock to control erosion as planned, failed to complete the work when fish weren't present and altered the streamside vegetation.
The creek's watershed, which extends into Surrey, supports chum and coho salmon and cutthroat trout.
BNSF must pay $70,000 to the Environmental Damages Fund toward proper management, conservation and protection of fisheries and fish habitat in the Cougar Creek watershed, as well as a separate $5,000 fine.