This post examines the key water and climate developments shaping California as Water Year 2026 begins.
I summarize the NOAA La Niña forecast, current reservoir conditions, long‑term glacier loss in the Sierra Nevada, policy debates over the Delta Conveyance Project and groundwater governance, and coastal and marine risks including sea‑level rise and an unprecedented marine heat wave.
My perspective draws on three decades of water resource science and management.
Overview: a year of contrasts — wet hope, persistent risk
California enters the new water year with a mix of encouraging and alarming signals.
Lake Oroville is reported at 109 percent of average for this date, offering some immediate relief.
Yet forecasts point to significant variability: NOAA assigns a 71 percent chance of La Niña this fall, a pattern historically associated with both regional drought persistence and episodes of intense winter storms.
La Niña and extreme weather risks
La Niña alters storm tracks and can amplify extremes.
For California, that often means a greater chance of dry spells in Southern California and heightened flood risk in parts of the Central Valley and Sierra foothills when storms do arrive.
Preparedness should therefore span both drought contingency and flood mitigation measures.
Glacier loss, marine heat waves, and coastal threats
Beyond seasonal variability, long‑term climate change is eroding the state’s natural reservoirs.
Scientists now project that the ancient glaciers of the Sierra Nevada, present for roughly 30,000 years, are likely to disappear by 2100 if current warming trajectories continue.
The loss of glacier mass reduces late‑season streamflow and resilient cold‑water refugia for aquatic species.
Compounding inland risks is a major marine heat wave off the Pacific — described as the fourth largest since 1982.
Warmer ocean conditions affect fisheries, coastal ecosystems, and can influence atmospheric patterns that feed back into California’s weather.
Sea‑level rise and shoreline adaptation
Bay Area communities from San Rafael to low‑lying shorelines face increasing tidal flooding and erosion.
State and local initiatives are developing shoreline adaptation plans, but implementation requires funding, land‑use coordination, and community engagement to balance protection with equitable outcomes.
Policy flashpoints: conveyance, groundwater, and budgeting
Several policy debates will shape how California manages water risks in the coming year.
The Kern County Water Agency is urging federal leaders to redirect funds from high‑speed rail to the Delta Conveyance Project, arguing the project is vital for the state’s economy and food security.
The Department of Water Resources has released a community guide outlining potential construction and operational impacts of the project — noise, traffic, and effects on well water are central community concerns.
Meanwhile, groundwater governance continues to evolve under the Sustainable Groundwater Management Act (SGMA).
Two adjudication bills diverged in fate: AB 1466 awaits the governor’s signature while AB 1413 was shelved.
Farmers and ranchers are facing higher fees, including new volumetric charges and late‑payment penalties, fueling debate about affordability and compliance.
Groundwater trading and equity
The California Water Commission is exploring groundwater trading as a tool for sustainability.
Trading can improve efficiency, but challenges remain around monitoring, accountability, and equity.
Ensuring small farmers and disadvantaged communities are not disproportionately harmed is a key concern.
Key takeaways for water managers and communities:
California’s Water Year 2026 will test the state’s ability to act proactively across short‑term operations and long‑term planning.
The coming months should clarify winter precipitation patterns.
Here is the source article for this story: WEEKLY WATER NEWS DIGEST for Sept. 28-Oct. 3: Happy New Water Year 2026!; La Niña expected to bring ‘extreme’ weather patterns statewide; Sierra Nevada’s glaciers will soon be gone; “Death of SGMA” predicted after groundwater bill is tabled; and more …