MRW Environmental, LLC

Wetland and Natural Resource Consulants

Streams and Hydrologic Determinations

ordinary high water mark illustration

MRW Environmental personnel have the expertise to conduct a variety of hydrologic determinations that can be critical in some projects.  The two most common are stream determinations and ordinary high water mark (OHWM) determinations.  Standardized procedures have been developed for both determinations and MRW personnel have the training and capability to conduct to conduct such surveys.  Our personnel are certified by TDEC to conduct stream determinations and although no such formal certification is available for OHWM determinations, we are among the few firms in the region with such expertise.  


Stream Determinations
The classification of a watercourse as a stream or as a wet weather conveyance can be one of the most significant factors that influences how a development project proceeds.  Potential impacts to a watercourse that is classified as a stream generally requires that a developer redesign the project to avoid the impacts or purchase mitigation credits from a stream mitigation bank.  Such credits are expensive and can add dramatically to the cost of a project.  In some instances, the classification of a watercourse will be obvious, but in many instances it is not clear and the decision comes down on how 1 or 2 of the questions within the protocol are answered.  MRW personnel are highly trained and can determine the status of watercourses to ensure that the calls made by agency personnel are correct.  If streams are present, we determine the best mitigation option for our clients and work with the regulatory agencies to minimize delays and expense.  

Ordinary High Watermark (OHWM) Determinations
The OHWM point can be important in projects situated adjacent to rivers, lakes, and reservoirs.  If a project or a portion of a project is below the OHWM, it can be subject to regulations under either Section 404 or under Section 10 of the Rivers and Harbors Act.  MRW personnel have the training to rapidly determine the precise location of the OHWM to ensure that the calls made by agency personnel are correct.  If a portion of a project is below the OHWM, we work with the regulatory agencies to determine the best option for our clients and work with them to minimize delays and expense.