This project identifies potential applications and barriers to the use of screening models for developing site-specific nutrient goals, and describes how screening-level models should be applied for nutrient-related applications. The project developed the Stream Nutrient Screening Tool (SCREEN-NUT), a QUAL2Kw-based screening tool for stream environments. SCREEN-NUT can be used in executing screening-level evaluations of stream responses to changes in nutrient inputs. It is included with this report in accompanying zipped files. Appendix A of the report provides a User’s Guide for SCREEN-NUT.

SCREEN-NUT was applied for the three case studies examined for the testing phase of this project. Though the results confirmed the utility of screening models for a wide variety of applications, they did confirm the expected result that screening models are not highly accurate for predicting absolute levels of responses, and so uncalibrated screening models should not be directly used for setting nutrient wasteload allocations, but can support a variety of other regulatory and non-regulatory activities, including prioritization of technology-based treatment tiers, exploring the benefits of nitrogen versus phosphorus reduction, and providing technical support to water quality trades or variances. This work builds on WRF’s previously developed modeling guidance for site-specific nutrient goals (LINK1T11) and an associated nutrient modeling toolbox. Published in 2020.

This Water Research Foundation report was originally funded as WERF project LINK4T17 and was published in 2020.