As wildfires in much of the western United States increase in size, frequency, and severity, understanding the impact of these fires on water yield from forested headwater basins is essential to successful management of water resources. The current study examines the changes in partitioning of the hydrologic cycle in the Mill Creek Basin that follow the Chippy Creek Fire in Montana, USA, due to alterations to the vegetative regime. The analysis utilizes remote sensing‐based vegetation indices and evapotranspiration, a model‐interpolated precipitation product, and discharge data to assess annual water budgets and vegetative regimes in the Mill Creek Basin. After being almost 90% burned in the Chippy Creek Fire, vegetation in the catchment has shifted from almost exclusively mixed conifer forest to sagebrush scrubs and grasses. This shift in vegetation is accompanied by abrupt shifts in partitioning of the water budget, resulting in an altered ecohydrologic regime. Post‐fire, evapotranspiration decreases annually by 250 mm (46%), and evaporative fraction decreases by 0.53. However, evapotranspiration product biases may overestimate this decrease from pre‐ to post‐fire. This decrease in evapotranspiration results in an annual increase in streamflow of 136 mm, a 21% increase in the runoff ratio, and a 140% increase in water yield. These changes to the water budget are consistent for 10 years post‐fire and show no trend towards pre‐fire values during the study period. Results will help inform planning and management of water resources downstream of forested catchments that have been impacted by wildfire.

This case study introduces students to the impacts that wildfires have on water resources as well as the challenges associated with managing these risks. By examining the development of a collaborative watershed group galvanized by the 2012 High Park Fire in Colorado, the case engages with the longstanding conundrum of how better to align ecological and social scales in natural resources management. It explores the role that collaborative groups are playing in addressing water resources problems at the watershed scale despite fragmented governance at that scale. A phased case study format allows students to investigate the motivations of diverse stakeholders and appreciate the challenges faced in watershed-based collaboration after a catalyzing event, such as a wildfire. Upon completion of the lesson, students will be able to (1) explain wildfires’ impacts to water resources and stakeholders; (2) assess the challenges and benefits of approaching management based on the physical boundaries of a watershed, rather than political boundaries; (3) identify and interrogate how collaborative watershed groups form as well as the factors that are key to their success; and (4) evaluate the outcomes of these collaborative efforts and their ongoing strengths and opportunities as well as their limitations and challenges. This line of inquiry is increasingly significant as collaborative watershed management groups proliferate in the United States, in many instances catalyzed by a disaster. Ultimately, this case study explores how collaborative watershed groups emerge and the role(s) they play in tackling long-term, multi-jurisdictional, and watershed-scale management challenges.

Outdoor water use represents over 50% of total water demand in semiarid and arid cities and presents both challenges to and opportunities for improved efficiency and water resilience. The current work adapts a remote sensing‐based methodology to estimate growing season irrigation rates at the census block group scale in Denver, Colorado. Results show that city‐wide outdoor water use does not change significantly from 1995 to 2018, while per capita water use and total water use significantly decrease from 2000 to 2018. Because total water use, but not outdoor use, is decreasing, the percent of water used outdoors significantly increases across the city from 2000 to 2018. Climate variables account for one‐quarter of interannual variation in mean irrigation rates due primarily to changes in temperature, not precipitation. Percent impervious land cover exhibits a significant inverse nonlinear relationship with irrigation rates at the census block group scale. Finally, 38% of Denver census block groups show significantly increasing irrigation rates between 1995 and 2018 driven primarily by increasing temperatures. The increasing proportion of water used for irrigation highlights the importance of outdoor demand management for urban water systems as indoor efficiencies improve. We advocate that resilient water systems necessitate integrated land use, infrastructure, and water planning in the face of urban growth and climate change. While minimizing irrigated urban areas may reduce demand, remaining green spaces should be designed to maximize multiple benefits including reductions in water demand and urban heat islands, stormwater management, and recreation to improve the sustainability of growing cities.

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