The 2002 Hayman Fire, more than any forest fire before it, demonstrated the tenuous link between wildfire and water quality. That fire burned more than 160,000 acres in the South Platte River watershed in forests close to population centers along Colorados Front Range. Our earlier work documented significant, lasting changes in water quality after the Hayman Fire. We used a network of stream monitoring sites established before the fire to compare unburned watersheds and those burned to varying extents by the Hayman Fire. We found that stream nitrate, suspended sediment and temperature remained elevated in extensively burned drainages during five years following the fire. Importantly, in contrast to general expectations regarding post-fire recovery, we saw little evidence that stream nitrate or temperature had begun to recover to pre-fire levels within 5 years of the fire. Understanding of the short term effects of wildfire on delivery of clean water, aquatic habitat, and channel stability has advanced since 2002, following large wildfires in western North America and elsewhere. However, recent and projected climatic conditions predict more large fires in the future, and information about the long-term effects of large wildfires that is critical to inform investment decisions about water treatment and clean water delivery remains scarce. The consequences of dissolved organic matter flux from forests watersheds on potentially toxic by-products of water treatment has become a global water quality concern, yet it the role of wildfire on export of these compounds is largely unknown. This proposed study expands on our original data to examine changes in water quality and treatability during more than 12 years after one of Colorados largest wildfires. We propose to build on our previous characterization of watersheds affected by the Hayman Fire and integrate additional water quality constituents of concern for water treatability in the following ways: " Sample and analyze stream water nutrients, sediment and temperature across our monitoring network 12-15 years after the fire. " Assess how post-fire water quality varies among watersheds based on the extent and severity of the area burned. " Conduct monthly and storm event sampling to capture hydrologic variability from seasonal changes and short-lived, high flow events. " Analyze potential formation of disinfection by-products (DBPs) after chlorination treatment of water from watersheds burned by the Hayman Fire and characterize dissolved C and N constituents. " Sample downstream of the Hayman Fire along the Platte River to estimate nutrient, carbon and sediment fluxes to Denver Waters treatment facility. This project and the diverse team of investigators, cooperators and stakeholder have good potential to deliver a range of scientific products to user groups interested in the long-term consequences of large wildfires on water quality and treatability.