Science Inventory

Watershed Management Optimization Support Tool (WMOST) v2: User Manual and Case Studies


Detenbeck, N., M. Tenbrink, R. Abele, J. Leclair, T. Garrigan, V. Zoltay, B. Small, A. Brown, I. Morin, AND A. Morrison. Watershed Management Optimization Support Tool (WMOST) v2: User Manual and Case Studies. U.S. EPA Office of Research and Development, Washington, DC, EPA/600/R-15/059, 2016.


The U.S. Environmental Protection Agency (US EPA) has endorsed the concept of IWRM, focusing on coordinated implementation of stormwater and wastewater management[1], and several states and river basin commissions have already started to implement IWRM[2] (including drinking water management as well). Beginning with the American Recovery and Reinvestment Act (ARRA), and continued with 2010 Appropriations language, Congress mandated a 20% set-aside of SRF funding for a “Green Project Reserve (GPR)”, which includes green infrastructure and land conservation measures as eligible projects in meeting water quality goals. The utilization of the GPR for green infrastructure projects has been relatively limited and responses have varied widely across states. According to a survey of 19 state allocations of Green Project Reserve funds, only 18% of funds were dedicated to green infrastructure projects and none of these projects were categorized as conservation planning to promote source water protection6. In order to assist communities in the evaluation of GI, LID, and land conservation practices as part of an IWRM approach, EPA Office of Research and Development, in partnership with EPA Region 1, supported the development of the Watershed Management Optimization Support Tool (WMOST). WMOST is based on a recent integrated watershed management optimization model that was created to allow water resources managers to evaluate a broad range of technical, economic, and policy management options within a watershed (Zoltay et al. 2010). This model includes evaluation of conservation options for source water protection and infiltration of stormwater on forest lands, green infrastructure stormwater BMPs to increase infiltration, and other water-related management options. The current version of WMOST focuses on management options for water quantity endpoints. Additional functionality to address water quality issues is one of the high priority enhancements identified for future versions. WMOST is implemented with a user-friendly interface in Excel for data input and output display, supported by VBA coding with linear optimization accomplished through linkage to LP-solver. Development of the WMOST tool was overseen by an EPA Planning Team. Priorities for update and refinement of the original model were established following review by a Technical Advisory Group comprised of water resource managers and modelers. Case studies for each of three communities were developed to illustrate the application of IWRM using WMOST; two of these case studies are presented in the user guide. WMOST was presented to stakeholders in a workshop held at the EPA Region 1 Laboratory in Chelmsford, MA in April 2013, with a follow-up webinar on the Danvers/Middleton case study in May 2013. Version 2 was tested with a case study involving Halifax, MA and the Monponsett Ponds watershed. Version 2 of WMOST includes functionality to aid users in acquiring input data for hydrology and BMP effectiveness, for evaluating management options over a range of historic climate variability, and for evaluating flooding risks and costs during the optimization analysis. [1]Nancy Stoner memo: [2] AWRA. 2012. Case Studies in Integrated Water Resources Management: From Local Stewardship to National Vision. American Water Resources Association Policy Committee, Middleburg, VA.


The Watershed Management Optimization Support Tool (WMOST) is a decision support tool that evaluates the relative cost-effectiveness of management practices at the local or watershed scale. WMOST models the environmental effects and costs of management decisions in a watershed context; that is, accounting for the direct and indirect effects of decisions. The model considers water flows and does not consider water quality. It is spatially lumped with options for a daily or monthly modeling time step. The optimization of management options is solved using linear programming. WMOST is intended to be a screening tool used as part of an integrated watershed management process such as that described in EPA’s watershed planning handbook (EPA 2008). WMOST serves as a public-domain, efficient, and user-friendly tool for local water resources managers and planners to screen a wide-range of potential water resources management options across their jurisdiction for cost-effectiveness and environmental and economic sustainability (Zoltay et al., 2010). Practices that can be evaluated include projects related to stormwater, water supply, wastewater and land resources such as low-impact development (LID) and land conservation. WMOST can aid in evaluating LID and green infrastructure as alternative or complementary management options in projects proposed for State Revolving Funds (SRF). In addition, the tool can enable assessing the trade-offs and co-benefits of various practices. In WMOST v2, the Baseline Hydrology and Stormwater Hydrology modules assist users with input data acquisition and pre-processing. In addition, the Flood module allows the consideration of flood damages and their reduction in assessing the cost-effectiveness of management practices. The target user group for WMOST consists of local water resources managers, including municipal water works superintendents and their consultants. Theoretical documentation is provided in a separate EPA report (EPA/600/R-15/058)

Record Details:

Product Published Date:01/29/2016
Record Last Revised:02/03/2016
OMB Category:Other
Record ID: 311013