The hydrologic cycle plays a crucial role in Earth's ability to sustain the complex ecosystems that make the planet rich and diverse. As the world's population increases, water resources may become limited and future societies will need advanced knowledge and tools to make informed decisions about water management. Nonetheless, hydrologic science remains a deemphasized component of K-12 education. Studies show that even science, technology, engineering, and mathematics (STEM) programs may not prepare students adequately to analyze hydrologic data and make critical decisions involving water.

In response to the need for improved knowledge and understanding of water systems, this study focuses on the design, implementation, and evaluation of multiple multi-year professional development programs for K-12 teachers (n = 89) focused on teaching and learning about water. The study aims to answer the following questions: i. What factors influence teachers' self-efficacy and content knowledge regarding water curriculum in the classroom? ii. Were PD programs successful at improving teachers' knowledge and ability to enrich students' water education? iii. What tools were useful in improving teachers' ease and comfortability to teach hydrologic science in the classroom?

We used a mixed methods approach, including data from pre and posttests, online content learning modules, a self-characterization survey and qualitative feedback on the programs. Quantitative analysis was employed to correlate factors influencing teachers' pretest, posttest, and change scores. Qualitative methods were used to analyze teacher self-efficacy, classroom practices and overall program success. Results showed that geographic location, years of teaching experience, number of students, and grade level were statistically significant factors regarding teachers' water content knowledge. The professional development programs were beneficial at improving teachers' knowledge of hydrologic processes and self-efficacy for supporting student learning about water. In addition, teacher feedback provided several effective instructional tools.