Introduction

As part of the Global Commons Alliance, the Science Based Targets Network (SBTN) collaborates with the Earth Commission to define safe planetary boundaries that help prevent the crossing of irreversible tipping points and to support a stable, resilient planet on which humanity can thrive. SBTN brings together more than 80 leading global organizations that collectively develop rigorous methodologies for setting science-based targets, guiding companies and cities in understanding relevant biophysical and social thresholds, identifying the interconnections among targets, and defining the actions that follow from them.

Freshwater is one of the critical systems these targets address. The Freshwater Quantity Target (FQT) forms part of SBTN’s broader set of Targets for Nature, drawing on the latest hydrological science to define what is necessary to meet local freshwater thresholds and enabling actors to align with Earth’s limits and broader societal sustainability goals. Central to this is the concept of environmental flows (e-flows), defined as the quantity, timing, and quality of freshwater flows and levels necessary to sustain aquatic ecosystems, which in turn support human cultures, economies, sustainable livelihoods, and overall well-being. Setting meaningful freshwater targets therefore requires robust hydrological models and e-flow thresholds to underpin the target-setting process.

To meet this need, SBTN developed the Basin Threshold Tool Framework v0.1 (BTT v0.1) - a relational database of data, methods, and supporting information designed to reduce the burden on companies when setting science-based freshwater targets for surface water. The tool aligns with existing SBTN Step 3 guidance (SBTN, 2024b; SBTN, 2023a) and is intended for a broad range of users, including companies, academics, and local water management authorities.

The BTT Framework is guided by five core development principles:

  1. Be consistent with the purpose of SBTN and its water stewardship approach.
  2. Apply a basin-scale understanding of how natural and socio-cultural systems interact with and influence water flows and levels.
  3. Establish thresholds that aim to protect, maintain, and restore the desired state of nature.
  4. Apply international best practices and a precautionary approach as the starting point for identifying environmental flow estimates.
  5. Adhere to the FAIR data principles—Findability, Accessibility, Interoperability, and Reusability.

The BTT Framework is supported by a Technical Advisory Group (TAG) comprising Angela L. Bowman, Chris W. S. Dickens, David W. Dilks, Michael E. McClain, Mathis L. Messager, Samuel Sandoval-Solis, Ben Stewart-Koster, Rebecca E. Tharme, Michele Thieme, Dave Tickner, and Allen Townsend.

The Center for Geospatial Solutions (CGS), part of the Lincoln Institute of Land Policy, is developing a web-based platform to support the BTT framework implementation. The platform transforms data from relational databases into an intuitive, interactive decision-support tool that enables companies and other stakeholders to explore freshwater sustainability information, set science-based freshwater targets, and assess the level of effort required to reduce water consumption. By making environmental flow requirements, water availability, and reduction targets accessible at the basin scale, the platform supports informed decision-making for the sustainable management of freshwater resources globally.