Rationale: While the importance of legacy effect characterization to interpreting long-term records of ecological conditions has continued to emerge (Bain et al. in review “Legacies in Material Flux: Structural Catchment Changes Pre-date Long-term Studies” BioScience) some early structural legacies (e.g. substantial soil losses to erosion) are challenging to characterize with controlled experiments. However, the extended observations of hydrologic conditions at long-term ecological research sites allow for the calibration and validation of hydrologic models (Sivandran et al. 2008 ,Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract H21F-0888). Reconstructions of pre-legacy landscapes can be explored with such models. Further, the replication across long-term research sites can provide additional insight by examining ecosystem response across relevant contrasts. We propose to convene a synthesis working group to: (1) Develop tRIBS+VEGGIE models for several long-term sites (BES, HBR, KNZ) using contemporary long-term data, (2) Develop scenarios of conditions during pre-European settlement periods and model these conditions to examine potential legacy changes in hydrology imparted to the landscape and current eco-hydrological systems.