Risk‐based Approach to Designing and Reviewing Pipeline Stream Crossings to Minimize Impacts to Aquatic Habitats and Species

Extensive new pipeline systems proposed to transport natural gas and oil throughout North America will potentially result in thousands of new stream crossings. The watercourses encountered at these crossings will range from small, ephemeral headwater streams to large, perennial mainstem rivers; from dynamic gravel-bed streams to stable bedrock channels; and from steep, source reaches to low gradient, response reaches. Based on past experience at pipeline crossings, the potential for both short and long-term negative impacts on aquatic habitat and species is substantial. In assessing potential hazards to aquatic habitat and species, the diverse physiography and ecology of the stream affected, combined with the number and range of new pipelines proposed, pose significant challenges for project developers charged with collecting, stratifying, evaluating, analysing, interpreting, and presenting stream crossing data in formats that are accessible, usable and useful. It is equally challenging for project reviewers to detect, distill and summarize potential project impacts and then identify reasonable options for their avoidance, minimization,andmitigation.Toaddresstheseconcerns,theUSFishandWildlifeService,inconjunctionwithRubyPipeline,LLC,developedapipeline crossing framework and risk analysis approach to stratify potential aquatic impacts, based on both stream characteristics and project types. In this approach, pipeline crossings are ranked in terms of relative short and long-term risk to aquatic habitat and are then analysed, designed, and monitored in ways appropriate to their risk. This approach allows project developers and reviewers to focus resources and monitoring on the crossings that present the highest risks to aquatic habitat and species, while expediting design and construction, and minimizing the monitoring of low-risk crossings. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.