Marc Leisenring, P.E.

Marc Leisenring is a Principal Water Resources Engineer based in Oregon with more than 15 years of experience focused on stormwater master planning, watershed and storm system modeling, environmental data analysis, regulatory compliance, and water quality management.

Marc has developed water quality models and decision support tools for clients to support environmental impact analyses and TMDL assessments, prepared and implemented monitoring plans, and worked with academics, regulators, and program managers to identify mutually agreeable solutions to his clients" complex water resources problems. He has been key team member for the International Stormwater Best Management Practice (BMP) Database ( project since his hire in 2001 and regularly conducts analyses of the performance datasets to support BMP selection, design, and pollutant load modeling efforts. Marc helped develop pollutant load reduction modeling tools for the Lake Tahoe Basin and the City of Los Angeles, which are used for regional water quality improvement planning. He also led stormwater modeling tasks to support integrated capital improvement planning projects for combined sewer infrastructure in the Cities of Akron, Ohio and Chicago, Illinois. For the Chicago project, and a similar project for the City of Calgary, Alberta, he utilized optimization software to identify strategic locations for implementing green infrastructure to minimize street flooding and manhole surcharging while minimizing life-cycle costs. In 2015, Marc was Geosyntec"s project manager for the Port of Portland"s $2.2M stormwater master plan project and also managed over 25 task orders for the Port between 2011 and 2017.

Experienced at preparing guidance documents, Marc has led or contributed to over a dozen national stormwater management, monitoring, and design guidance documents for the National Cooperative Highway Research Program (NCHRP), the Airport Cooperative Research Program (ACRP), the Federal Highway Administration (FHWA), the U.S. Environmental Protection Agency (USEPA), and the Water Environment & Reuse Foundation (WE&RF). For example, he led the preparation of the WE&RF report titled "Linking BMP Systems Performance to Receiving Water Protection - BMP Performance Algorithms" that provides computational approaches for estimating the performance of BMPs based on unit treatment processes. He also authored the statistical analysis chapter of the 2009 update to the USEPA Urban Stormwater BMP Performance Monitoring manual.  With his literature contributions and multiple speaking engagements at national water resources conferences and publically-accessible webinars, he has become a recognized expert in the fields of stormwater management and water quality data analysis.

Contact Marc Leisenring at This email address is being protected from spambots. You need JavaScript enabled to view it. or +1-971-271-5904.

Career Summary: Marc Leisenring, P.E.

  • Specialties: Pollutant Source Control and Stormwater Practice Selection and Design; Water Quality Data Management and Analysis; National Pollutant Discharge Elimination System (NPDES) Permit Compliance; Total Maximum Daily Load (TMDL) Implementation Studies; Stormwater Management and Monitoring Guidance
  • Practice Areas: Environmental Management, Water Management, Waste Management
  • Disciplines: Civil Engineering, Water Resources Engineering
  • Education: M.S., Civil and Environmental Engineering, Portland State University, 2011; B.S., Environmental Resources Engineering, Humboldt State University, 2001
  • Registration: Registered Civil Engineer, Oregon, 77895PE
Geosyntec Consultants
Geosyntec is a consulting and engineering firm that works with private and public sector clients to address new ventures and complex problems involving our environment, natural resources, and civil infrastructure.

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