Adaptive management is a theory that encourages environmental managers to engage in a continual learning process and adapt their management choices based on learning about new scientific developments. One such area of scientific development relevant to water management is bacterial genetics, which now allows scientists to identify when human sewage has seeped into unintended places. Source-specific bacterial testing in a variety of cities across the United States indicates there is human sewage in urban stormwater pipes. These pipes are designed to carry runoff from city streets and lots; sending untreated water directly into rivers, streams, and lakes. This scientific breakthrough could be highly useful to urban water managers because it helps identify sewage infrastructure problems that pose significant public health risks. While accepted within the scientific community, this research sought to understand the extent to which urban water managers were using this new monitoring method and, to the degree they were not, to identify the barriers. We designed our study to illustrate how municipal stormwater managers understand and adapt to highly relevant scientific developments in monitoring techniques. The research findings and analysis are based on qualitative research interviews with urban stormwater managers and their state and federal agency regulators to identify what encourages and discourages the application of useful scientific discoveries to better manage water systems, with a particular focus on how the law influences adaptive management. This research provides important insights into necessary legal and management reforms that must occur if the theoretical benefits of adaptive management are to be realized. Moreover, it adds to the theoretical research on adaptive management by providing a detailed case study of the barriers in practice to the adoption of adaptive management approaches.