Storms, Reservoirs, and Flood Risk
In Lois Henry’s most recent newsletter (The Splash) from SJVWater.org, she recommends Which Reservoirs To Watch across the San Joaquin Valley.
SJV Reservoirs to watch
“The recent water dump from Kaweah and Success lakes and incoming storm that promises to finally bring precipitation to the entire state made me think it was a good opportunity to orient readers about local rivers and reservoirs.
What better way to do that than MAPS and GRAPHICS, which are both conveniently provided by CDEC,the California Data Exchange Center.
This map (which you can click on to go to the original site) shows what's called "top of conservation" levels for our various reservoirs. That's the level dam operators set in the fall in order to keep enough space in the lake in case we have a really wet winter, so they have enough room for heavy precip and runoff.
Anything above the "top of conservation" levels is considered "encroachment" water, which is shown in red on graphic. Lakes Kaweah (Terminus Dam or TRM on this map) and Success were both encroached into the top of conservation levels…” Click here for the interactive reservoir map.
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Update from Wes Bowers of Lodi News-Sentinel
Update from Wes Bowers of Lodi News-Sentinel
Update from Steve Mann's About Town.....
Update from Steve Mann's About Town.....
Recent atmospheric river events and flood management reports highlight several Central Valley cities facing elevated flood risks in 2025
Here are the most vulnerable areas:
High-Risk Cities
Stockton
Flood factors: Located on the San Joaquin River, with parts of the city in a 100-year floodplain.
Recent mitigation: $100 million Smith Canal floodgate completed in 2024 to protect ~1,700 homes[6].
Current status: Federal flood insurance still required until 2025 despite new infrastructure[6].
Sacramento
Flood factors: At the confluence of the Sacramento and American Rivers; aging levees and urban expansion into floodplains.
Projected impact: NWS warns of "widespread shallow landslides" in saturated soils[13].
Fresno & Madera
Flood factors: Proximity to the Sierra Nevada foothills and San Joaquin River tributaries.
Forecast: 3+ inches of rain expected in mountain communities (e.g., Mariposa), increasing debris flow risks[9].
Chico & Redding
Flood factors: Near Sacramento River overflow zones; recent atmospheric rivers (Jan-Feb 2025) elevated regional streamflow[5].
Alerts: Under "slight risk" of excessive rainfall through early February[5].
Modesto & Merced
Flood factors: San Joaquin River Basin cities with aging SPFC levees protecting $70B+ in assets[3].
State plan: Targeted for multi-benefit projects under the Central Valley Flood Protection Plan[8].
At-Risk Regions
San Joaquin Valley
Levee breaches, agricultural flooding [3][8]
Sierra Foothills
Debris flows, urban flooding [9][16]
Russian River Basin
Riverine flooding (Guerneville area) [13]
Contributing Factors
Atmospheric Rivers: Prolonged AR events in Jan-Feb 2025 left soils saturated, increasing runoff risks[4].
Burn Scars: Recent wildfires (Eaton, Palisades) in foothills heighten debris flow risks[5].
Snowpack Melt: Sierra snowpack at 150% of average threatens spring flooding[7].
Ongoing Mitigation Efforts
Central Valley Flood Protection Plan: Prioritizes 30-year investments in levees and bypasses[8].
Lower San Joaquin River Project: $1.4B Army Corps initiative to reduce Stockton flood risks[6].
While the risk of flooding in Lodi is considered low for this storm, authorities urge residents in other areas listed above to monitor alerts and prepare evacuation plans[12].
Sources
[1] Strong atmospheric river to impact California with heavy rain and mountain snow https://watchers.news/2025/02/11/strong-atmospheric-river-to-impact-california-with-heavy-rain-and-mountain-snow/
[2] Map Shows California Cities Getting Hit Hardest by Huge Rainstorm https://www.newsweek.com/map-california-cities-hit-hardest-huge-rainstorm-2029571
[3] California Central Valley Program - - American Rivers https://www.americanrivers.org/california-central-valley-program/
[4] Prolonged atmospheric river event to bring heavy rainfall and snow to Northern and Central California https://watchers.news/2025/01/30/prolonged-atmospheric-river-event-to-bring-heavy-rainfall-and-snow-to-northern-and-central-california/
[5] California flood watch raises risk of mudslides days after fire ... https://www.nbcnews.com/weather/storms/california-flood-watch-raises-risk-mudslides-days-fire-containment-rcna190422
[6] California's first floodgate aims to remove hundreds of Central Valley ... https://www.cbsnews.com/sacramento/news/californias-first-floodgate-stockton/
[7] California to stay drought-free through 2025 following 2 winters of ... https://www.accuweather.com/en/weather-forecasts/california-to-stay-drought-free-through-2025-following-2-winters-of-epic-storms-accuweather-experts-say/1627328
[8] Central Valley Flood Protection Plan https://water.ca.gov/Programs/Flood-Management/Flood-Planning-and-Studies/Central-Valley-Flood-Protection-Plan
[9] Central California weather: Storm system bringing flood concerns and snow https://abc30.com/post/central-california-weather-storm-system-bringing-flood-concerns-snow/15897594/
[10] Atmospheric River Map Shows Where in California Will Be Hit https://www.newsweek.com/atmospheric-river-map-california-2029454
[11] The 2024-25 Budget: Flood Management Proposals https://lao.ca.gov/Publications/Report/4856
[12] California on 'high alert' as looming storm threatens flooding, mudslides, heavy snow https://www.usatoday.com/story/news/nation/2025/02/12/california-atmospheric-river-flood-mudslide-forecast/78450088007/
[13] Officials race to protect homes, consider evacuations as major ... https://www.latimes.com/california/story/2025-02-12/southern-californias-strongest-storm-of-winter-is-here-high-risk-of-flooding-debris-flow
[14] California Has Its Own "Hurricanes"—and We Are Just as ... https://www.ppic.org/blog/california-has-its-own-hurricanes-and-we-are-just-as-vulnerable-to-flooding-as-the-southeast/
[15] DAILY DIGEST, 2/12: California braces for flooding and mudslides as atmospheric river looms; State proposes retroactive changes to farmland retirement program that some fear could pull rug out from ongoing projects; Update on State Water Board’s SGMA in https://mavensnotebook.com/2025/02/12/daily-digest-2-12-california-braces-for-flooding-and-mudslides-as-atmospheric-river-looms-state-proposes-retroactive-changes-to-farmland-retirement-program-that-some-fear-could-pull-rug-out-from-on/
[16] California Storm Will Bring Flooding to Areas Burned by Wildfires https://www.nytimes.com/2025/02/12/weather/la-rain-california-forecast.html
[17] Flash Flood, Debris Flow Risk as Storm Hits Wildfire Burn Areas in California https://www.newsweek.com/california-storm-flash-flood-debris-flow-wildfire-burn-areas-2029636
[18] Snow and freezing rain pummel the mid-Atlantic while California prepares for likely flooding https://nypost.com/2025/02/12/us-news/snow-and-freezing-rain-pummel-the-mid-atlantic-while-california-prepares-for-likely-flooding/
[19] Cities with the Most Properties at Risk of Flooding https://cvfpb.ca.gov/news/cities-with-the-most-properties-at-risk-of-flooding/
[20] Flash Flood Watch issued for Los Angeles ahead of strong atmospheric river, California https://watchers.news/2025/02/11/flash-flood-watch-issued-for-los-angeles-ahead-of-strong-atmospheric-river-california/