Hydrology Weekly Brief: June 17–23, 2025
This week in hydrology, we saw significant developments across water policy, environmental regulations, and groundbreaking research. Updates on U.S. drought conditions highlighted persistent dryness in the Northwest, while new EPA adjustments to PFAS rules offered utilities more compliance time. We also got insights into ancient groundwater responses to climate change and new proposals from the U.S. Army Corps of Engineers.
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EPA Adjusts PFAS Regulations, Offers Utilities More Time
On June 17, 2025, reports indicated that the U.S. Environmental Protection Agency (EPA) is planning to adjust existing federal limits on certain PFAS, often referred to as “forever chemicals”. Under these revised rules, the EPA will primarily enforce limits for two specific types, PFOA and PFOS, and water utilities will now have until 2031, an extension from the previous 2029 deadline, to comply with these federal limits. This decision comes amidst ongoing lawsuits from water utility membership groups who argue that the initial federal rules were unreasonable and would be impossible to enforce, highlighting the tension between environmental protection goals and the practical realities faced by utilities.
Published: June 17, 2025
More time and fewer regulations for water utilities on 'forever chemicals' | WUSF -
Ancient Groundwater Insights Reveal Climate Susceptibilities
New research, published on June 17, 2025, in the journal Science Advances, offers compelling insights into how ancient groundwater levels in two distinct U.S. regions—the arid Southwestern U.S. and the rainy Pacific Northwest—responded to past climate changes. The study, which analyzed fossil groundwater data from 17 wells across Washington and Idaho, revealed a remarkable stability in Pacific Northwest groundwater levels despite periods of increased rainfall during a significant climate shift. In stark contrast, the Southwest experienced marked groundwater depletion during similar climatic transitions, underscoring its inherent susceptibility to climate change impacts on water resources.
Published: June 18, 2025
Ancient Groundwater Insights Highlight Regional Susceptibilities to Climate -
Sac State Professor Turns Waterways into Living Labs for Environmental Innovation
Julian Fulton, an Environmental Studies professor at Sacramento State, is transforming California’s waterways and the university campus itself into dynamic living laboratories for environmental innovation. His research is dedicated to sustainable water systems and the overall health of California’s vital water resources, actively involving his students in hands-on projects. One recent focus for his water quality group has been the emerging pollutant 6-PPD, an antioxidant found in tires that washes into waterways during rainstorms and harms coho salmon populations.
Published: June 20, 2025
Sac State professor turns California’s waterways – and the campus – into a living lab for environmental innovation | Sacramento State
Tools & Tips
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HydroForecast: Next-Gen AI for Streamflow Forecasts
Upstream Tech announced the next-generation architecture for their HydroForecast AI streamflow forecasts on June 17, 2025. HydroForecast is highlighted as a highly accurate, adaptable, and user-friendly tool that leverages advanced artificial intelligence to provide reliable predictions, performing exceptionally well even in extreme weather conditions.
HydroForecast -
HEC-RAS 2025: A Major Overhaul for Hydrologic Modeling
The U.S. Army Corps of Engineers’ Hydrologic Engineering Center (HEC) is rolling out HEC-RAS 2025, a completely redesigned version of their widely used river analysis system. This significant overhaul includes a modern user interface, enhanced mesh generation capabilities, and an all-new compute engine built for scalability and cloud compatibility. The 1.0 release is targeted for late Fall 2025, promising a new era for hydrological simulations.
HEC-RAS 2025
Fun Fact
Did you know that the water coming out of your faucet today could contain molecules that dinosaurs drank millions of years ago? It’s true! The Earth has essentially the same amount of water now as it did when it formed, constantly cycling through various forms and locations. Water is neither created nor destroyed; it simply changes phases—from liquid to solid to gas—and moves through various parts of the Earth and atmosphere.
We’d love to hear from you! Have you participated in any Hydrology events or utilized new Hydrology tools recently? Share your experiences or insights with us—we’re featuring selected community voices in next week’s edition.