Not a compliance determination. This page presents historical and regional U.S. Geological Survey groundwater data for reference only. It is not a compliance determination, a site assessment, or engineering advice. On-site water table depth varies sharply with location and season. Consult the Alaska on-site wastewater regulations (18 AAC 72) and a licensed engineer or surveyor before relying on these figures.
Anchorage · 61.05943°N · 149.77608°W
How deep is the water table here?
There is no active public groundwater monitoring well in central Anchorage. This page combines the sparse historical record near this spot with the nearest active USGS well, KB-6 in Chugiak (17 mi NNE), to show what the public record actually says about depth to water.
How is “water table” defined?
“The upper surface of a zone of saturated soil, including normal seasonal fluctuations, but excluding fluctuations caused by heavy rainfall or rapid snow-melt.”
For septic and foundation decisions the regulatory number is the annual high water table, not the depth on any single day. Alaska requires at least four feet of vertical separation between the bottom of a conventional drainfield and the annual high water table (18 AAC 72.520(d)), because treatment happens in the unsaturated soil above the water. That is why a single reading, especially a dry-season low, can mislead.
What does the nearby water table look like?
Nearest historical reading
1970-09-01Driller log AACD1·002, 0.18 mi from the anchor. Near-target driller logs (1970 to 1986) range from 10 to 155 ft within 0.3 mi, so there is no single historical water table here. Click a marker to compare wells.
The continuous record: KB-6, Chugiak
KB-6 is the nearest well with an ongoing record. Its depth to water cycles seasonally between roughly 108 and 114 ft. The dashed line is a modeled seasonal baseline, a least-squares annual fit rather than a forecast. KB-6 sits 17 mi from this location, so treat it as a regional indicator.
Next steps
How would you measure it here?
To get the water table at a specific property you either drop a sensor into a well or map it from the surface with geophysics. Costs below are rough and instrument-only; they exclude the monitoring well itself, which is usually the largest line item (drilling a 20 to 150 ft well runs from a few thousand to tens of thousands of dollars).
| Method | Accuracy | Cost | Logger + transmission | Reading |
|---|---|---|---|---|
Manual water-level tape (e-line) Direct, needs a well | ±0.01 ft | $300 to 600 | Not needed (read by hand) | Spot |
Vented pressure transducer / logger Direct, needs a well | ±0.01 to 0.1 ft | $500 to 1,200 | $500 to 2,000 (logger plus cellular) | Continuous |
Vibrating-wire piezometer (Geokon 4500) Direct, grouted in | ±0.1% full scale | $600 to 1,500 | $500 to 2,000 (logger plus cellular) | Continuous |
Downhole radar / ultrasonic level Direct, needs a well | ±0.01 ft | $400 to 1,200 | $500 to 2,000 (logger plus cellular) | Continuous |
Soil-moisture / matric probes (TEROS) Indirect saturation profile | Infers the wet zone, not a depth | $150 to 400 each | $400 to 1,500 (logger plus cellular) | Continuous |
Ground-penetrating radar (GPR) Geophysical, no well | ±0.5 to 1 ft, only with dry-soil contrast | $200 to 600 / survey day (rented) | Not applicable | Spot |
Transient EM / resistivity (TEM, ERT) Geophysical, no well | ±1 to 3 m | $1,500 to 5,000 / survey day | Not applicable | Spot |
Timing
When should you take a measurement?
A sensor in a well reads any day. A surface radar survey does not. Ground-penetrating radar images the water table only when dry, unsaturated soil sits above the saturated zone, because that is what creates the reflection. After rain, or in the chronically wet ground common across Alaska, the whole column is near-saturated, the contrast disappears, and the water table is invisible to the radar.
So the question is timing. The calendar scores each upcoming day on how dry the ground is likely to be, from recent and forecast rainfall around this location.
Best upcoming window: Sat, Jul 18 (0% favorable)
Favorability is a first-order screen from daily precipitation (Open-Meteo) only. It cannot account for snowmelt, frozen ground, antecedent saturation, or soil type, so a geophysicist still makes the real call. It is not a guarantee of survey success.
Forecasted precipitation
Live ECMWF rain forecast around the anchor from Windy.com. Watch for an incoming dry stretch: that is when the overburden has the best chance of drying enough for radar to see the water table.
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Sign up for BeadedcloudNot a compliance determination. This page presents historical and regional U.S. Geological Survey groundwater data for reference only. It is not a compliance determination, a site assessment, or engineering advice. On-site water table depth varies sharply with location and season. Consult the Alaska on-site wastewater regulations (18 AAC 72) and a licensed engineer or surveyor before relying on these figures.