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#           January 18, 2022, Red Hill synoptic groundwater-level survey, Hālawa area, O‘ahu, Hawai‘i      

      May 26, 2022    

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On January 18, 2022, groundwater levels were measured in selected wells in the Hālawa area, O‘ahu, Hawai‘i, constituting a synoptic groundwater-level survey (shortened herein to “synoptic survey”) of the area. Groundwater levels were measured mainly from 9:00 a.m. to 12:00 p.m. (times listed in Hawai‘i standard time) and provide a snapshot of groundwater levels during the survey period. Following a reported fuel release that affected groundwater quality in the Red Hill area, several production wells were shut down in the weeks prior to the synoptic survey. These wells include the Red Hill Shaft (shut down on November 28, 2021) and the Hālawa Shaft (shut down on December 3, 2021, except for weekly, short-duration operations for water-quality sampling). Groundwater levels measured in wells during the synoptic survey ranged from 16.81 to 20.19 feet above mean sea level. The groundwater levels measured on January 18, 2022, were about 0.3 to 0.6 feet higher than those measured at common sites during a synoptic groundwater-level survey on December 23, 2021.

The groundwater levels collected during the multiagency synoptic survey contain uncertainty because of several potential sources of error associated with (1) the accuracy of the measuring tapes used, (2) the accuracy of the measuring-point altitude at the top of each well, (3) well plumbness and alignment, (4) human error, and (5) changing conditions during the survey period. Because of these potential sources of error, comparability of groundwater-level measurements may be affected. Some of the sources of uncertainty can be addressed and lead to improved accuracy and comparability of the groundwater levels. For example, uncertainty associated with the measuring-point altitudes can be addressed by resurveying measuring-point altitudes to a common vertical datum using consistent surveying methods.

## Citation Information

## Related Content

                  -              Data           
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January 1, 1994

####                 USGS Water Data for the Nation              

This collection provides access to water-resources data collected at approximately 1.5 million sites in all 50 States, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa and the Commonwealth of the Northern Mariana Islands. Online access to this data is organized around the categories surface water, groundwater, water quality, and water use.

#### Rylen K Nakama

##### Hydrologic Technician

Pacific Islands Water Science Center

rnakama@usgs.gov

808-690-9578

#### Jackson N Mitchell

##### Hydrologist

Washington Water Science Center

jnmitchell@usgs.gov

253-552-1616

#### Delwyn S Oki

##### Hydrologist

Pacific Islands Water Science Center

dsoki@usgs.gov

808-690-9598

## Related Content

January 1, 1994

####                 USGS Water Data for the Nation              

This collection provides access to water-resources data collected at approximately 1.5 million sites in all 50 States, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, American Samoa and the Commonwealth of the Northern Mariana Islands. Online access to this data is organized around the categories surface water, groundwater, water quality, and water use.

#### Rylen K Nakama

##### Hydrologic Technician

Pacific Islands Water Science Center

rnakama@usgs.gov

808-690-9578

#### Jackson N Mitchell

##### Hydrologist

Washington Water Science Center

jnmitchell@usgs.gov

253-552-1616

#### Delwyn S Oki

##### Hydrologist

Pacific Islands Water Science Center

dsoki@usgs.gov

808-690-9598

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####             Water Resources Mission Area - Headquarters        

USGS Headquarters12201 Sunrise Valley DriveReston, VA20192United States

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