Scientific modeling is a core practice used extensively in the geosciences to explain concepts, predict phenomena, and illustrate and represent interactions and relationships within complex Earth systems. One complex Earth system that spans K-12 standards for science teaching and learning is water. To help students become more scientifically-literate, teachers must support students' model-based reasoning about water systems. However, prior research has shown that teachers need support to effectively engage students in model-based experiences with water. To address this need, our team has designed and implemented multiple programs over the past five years to enhance professional learning of both preservice and inservice K-12 teachers spanning multiple externally-funded projects. A consistent thread in this work has been an emphasis on scientific modeling to teach and support students' learning about water systems. To meet the unique and varied needs of prospective and practicing teachers as professional learners, we designed rich learning opportunities for teachers to iteratively co-construct instructional materials, enhance their conceptual understanding of water-related phenomena, and reflect on samples of classroom instruction. We also supported teachers' engagement with computer-based water models, simulations, and visualizations as teaching and learning tools. Each project was research-based and developed to meet the unique needs of the population we sought to serve. In this presentation, we examine the different structures we utilized to address the needs of preservice and inservice elementary, middle, and high school teachers teaching about water using scientific models and modeling. We also discuss how each group struggled with various aspects of teaching their students about scientific modeling as a practice of science and how professional learning opportunities ameliorated aspects of those issues, providing examples and artifacts that could prove useful in others involved in geoscience teacher professional development, teacher education, curriculum implementation, and education research.