Arsenic in Central Oklahoma (Garber-Wellington) wells
Oklahoma DEQ says arsenic, chromium, selenium and uranium in parts of the Garber-Wellington aquifer sometimes exceed federal drinking water limits, in shallow and deep wells alike, so the only way to know about your well is a lab test.
Where the aquifer is
Oklahoma DEQ calls the Central Oklahoma aquifer, also known as the Garber-Wellington aquifer, a major source of drinking water for central Oklahoma.
USGS says the Central Oklahoma aquifer underlies about 3,000 square miles in Cleveland, Lincoln, Logan, Oklahoma, Payne, Pottawatomie and Seminole counties.
The Oklahoma Water Resources Board says the Garber-Wellington groundwater basin underlies 2,891 square miles of central Oklahoma.
Sources: Oklahoma DEQ; U.S. Geological Survey; Oklahoma Water Resources Board
What has been found in the water
The Oklahoma DEQ says arsenic, chromium, selenium and uranium in parts of the Garber Wellington (Central Oklahoma) aquifer sometimes exceed federal drinking water limits.
An earlier OWRB study that included deeper municipal wells found 15 percent of sampled wells over the arsenic limit, 11 percent over the uranium limit, 7.5 percent over selenium and 2 percent over chromium.
In OWRB's 2013 groundwater monitoring of 47 wells in the basin, nitrate, arsenic and uranium each exceeded a federal limit in one instance.
| Element | Limit (micrograms per liter) |
|---|---|
| Arsenic | 10 |
| Chromium | 100 |
| Selenium | 50 |
| Uranium | 30 |
Sources: Oklahoma DEQ; Oklahoma Water Resources Board; Federal limits for these metals
Does a deeper well have more arsenic?
Oklahoma DEQ says high levels turn up in both shallow and deep wells anywhere in that aquifer, so the risk is unknown until the water is tested.
USGS says arsenic in the Central Oklahoma aquifer tends to increase with depth.
USGS studies found a tendency for higher arsenic in the western, confined part of the aquifer.
USGS (2005) wrote that most private wells in central Oklahoma draw from the shallow part of the aquifer, less than 300 feet down, and that shallow wells rarely exceed the arsenic limit.
USGS reports arsenic as high as 232 micrograms per liter measured in the confined part of the aquifer in Norman, against a limit of 10.
USGS explains that arsenic is released into the water when the pH rises above 8.5.
OWRB explains that these elements are in the aquifer rock throughout and come loose at higher pH, which typically rises with depth.
Sources: Oklahoma DEQ; U.S. Geological Survey; Oklahoma Water Resources Board
Why it matters for your health
Oklahoma DEQ says arsenic can come from natural deposits or farm and industrial practices, and long term drinking can cause skin disorders, stomach, intestine and lung irritation, nerve problems and cancer.
EPA's drinking water limit for arsenic is 0.010 milligrams per liter (10 micrograms per liter), in force since January 23, 2006; long term exposure is linked to skin damage, circulation problems and a higher cancer risk.
Oklahoma DEQ says studies have shown elevated uranium can cause kidney damage.
EPA's limit for uranium is 30 micrograms per liter; above it the risks are cancer and kidney toxicity.
Sources: Oklahoma DEQ; U.S. EPA
How to test your well
Oklahoma DEQ notes that the state does not require private well testing, but owners may want these metals checked; DEQ's state lab supplies sample kits.
Oklahoma DEQ says all public water systems are checked periodically for arsenic, chromium, selenium and uranium; testing a private well is not required.
Oklahoma DEQ says a sample kit comes from its State Environmental Laboratory, (405) 702-1000 or (866) 412-3057, and results usually come back in about two weeks.
DEQ advises contacting the lab first for collection instructions and any special containers. Most labs provide sampling kits.
Oklahoma DEQ offers a special analytical fee for private drinking water wells that draw from the Central Oklahoma aquifer.
The Oklahoma DEQ State Environmental Laboratory charges a base fee of $64 for its Garber Wellington test list (arsenic, chromium, selenium, uranium). A prep test fee is added per sample.
The Oklahoma DEQ State Environmental Laboratory lists a base fee of $33 for a single arsenic analysis (EPA 200.8).
The Oklahoma DEQ lab fee schedule says a prep test fee is added to each sample on top of the base fees it lists.
The Tulsa Health Department lab charges $209.70 for its BETTER well package of common Oklahoma well tests.
Sources: Oklahoma DEQ; Oklahoma DEQ; Oklahoma DEQ Garber-Wellington test list; Tulsa Health Department BETTER well package
If your well is over a limit
Oklahoma DEQ says the best option, where feasible, is to buy water from a public water system, which must test and has ways to remove these elements.
If public water is not feasible, DEQ notes that commercial systems such as reverse osmosis and ion exchange advertise that they remove arsenic, chromium, selenium and uranium.
DEQ describes point of entry treatment as treating all the water as it enters the house, generally with sediment filters and iron granules that absorb the metals.
DEQ describes point of use treatment as treating water at one tap using granular ferric adsorption.
DEQ says both kinds of treatment cost money and need upkeep to keep working, so each should be looked into carefully before choosing.
Source: Oklahoma DEQ
Test for the basics too
A USGS and Oklahoma DEQ study notes that the state monitors deep public supply wells, but water from shallow domestic wells is not monitored.
In that 2003 to 2005 study, water from 3 of 23 shallow wells (13 percent) was over the nitrate limit of 10 milligrams per liter.
DEQ recommends testing every year for total coliform bacteria, nitrate/nitrite, conductivity and pH, especially after a new well or pump repair.
Sources: U.S. Geological Survey; Oklahoma DEQ
Sources and dates
- Oklahoma DEQ, read October 6, 2026https://oklahoma.gov/content/dam/ok/en/deq/documents/executive-offices/fact-sheets/Garber%20Wellington%20Aquifer.pdf
- U.S. Geological Survey, read October 6, 2026https://pubs.usgs.gov/fs/2005/3111/
- Oklahoma Water Resources Board, read October 6, 2026https://www.owrb.ok.gov/studies/groundwater/pdf/Garber-Wellington-Staff-Report-2019.pdf
- U.S. EPA, read October 6, 2026https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
- Oklahoma DEQ, read October 7, 2026https://oklahoma.gov/content/dam/ok/en/deq/documents/executive-offices/fact-sheets/Home%20Water%20Testing.pdf
- Oklahoma DEQ, read October 6, 2026https://oklahoma.gov/content/dam/ok/en/deq/documents/lab/SELSD-SD-008-R4%20Lab%20Services%20Fee%20Schedule%20FY27.pdf
- tulsa-health.org, read October 7, 2026https://tulsa-health.org/wp-content/uploads/2025/06/EHSLabPricing_v20250527.pdf
- U.S. Geological Survey, read October 6, 2026https://pubs.usgs.gov/publication/sir20065084
See Oklahoma test fees
Every published Oklahoma well water test fee, from the DEQ lab to the Tulsa Health Department, with its source.
See Oklahoma test feesCommon questions
Is there arsenic in my well in central Oklahoma?
Oklahoma DEQ says high levels turn up in both shallow and deep wells anywhere in that aquifer, so the risk is unknown until the water is tested. An earlier OWRB study that included deeper municipal wells found 15 percent of sampled wells over the arsenic limit, 11 percent over the uranium limit, 7.5 percent over selenium and 2 percent over chromium.
How do I test my well for arsenic in Oklahoma?
Oklahoma DEQ says a sample kit comes from its State Environmental Laboratory, (405) 702-1000 or (866) 412-3057, and results usually come back in about two weeks. The Oklahoma DEQ State Environmental Laboratory charges a base fee of $64 for its Garber Wellington test list (arsenic, chromium, selenium, uranium). A prep test fee is added per sample.
Does a deeper well have more arsenic?
USGS says arsenic in the Central Oklahoma aquifer tends to increase with depth. USGS (2005) wrote that most private wells in central Oklahoma draw from the shallow part of the aquifer, less than 300 feet down, and that shallow wells rarely exceed the arsenic limit. Oklahoma DEQ says high levels turn up in both shallow and deep wells anywhere in that aquifer, so the risk is unknown until the water is tested.
What removes arsenic from well water?
Oklahoma DEQ says the best option, where feasible, is to buy water from a public water system, which must test and has ways to remove these elements. If public water is not feasible, DEQ notes that commercial systems such as reverse osmosis and ion exchange advertise that they remove arsenic, chromium, selenium and uranium.