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Hanawi Stream near Nahiku, Maui, Hawaii.


Recent hydrologic conditions, Iao and Waihee aquifer areas, Maui, Hawaii

Water Levels in Wells

Water levels in observation wells

Introduction (summarized from US Geological Survey Water-Resources Investigations Report 00-4223)

Groundwater withdrawal from the Iao and Waihee aquifer areas has contributed to an overall decline in water levels that has resulted in a corresponding rise of the transition zone between freshwater and saltwater. Pumping from each well field generates a cone of depression that overlaps with the cones of depression from one or more of the other adjacent well fields. Water levels in the Iao aquifer area have been monitored for various periods of time since 1940. Available data indicate that water levels not only respond to pumping, but also correspond closely to the departure of the mean of the preceding 12 months of rainfall from the mean rainfall of the entire record. In addition, water levels fluctuate seasonally, with annual highs occurring in the winter and lows occurring in the late summer or early fall. Well-construction information is available for selected wells in the Iao and Waihee area.

The water levels presented have been adjusted for new measuring points for measurements made starting October 2003 and later. Water-level measurements made prior to October 2003 have not been adjusted. 

Additional information about the Iao aquifer area can be found in:

"Ground-water availability in the Wailuku Area, Maui, Hawai'i" by Stephen B. Gingerich, 2008, US Geological Survey Scientific Investigations Report 2008-5236

"The response of the Iao aquifer to groundwater development, rainfall, and land-use practices between 1940 and 1998, Island of Maui, Hawaii" by William Meyer and Todd K. Presley, 2001, US Geological Survey Water-Resources Investigations Report 00-4223

"Analytical versus numerical estimates of water-level declines caused by pumping, and a case study of the Iao aquifer, Maui, Hawaii" by Delwyn S. Oki and William Meyer, 2001, US Geological Survey Water-Resources Investigations Report 00-4244

Active Monitoring Sites

Follow the links to compare recent and historical water levels

Waikapu 1

Waikapu 2

Test Hole B Waiehu

Waiehu Deep Monitor well

Kanoa Test Hole

Kepaniwai Observation Well

These active groundwater stations are operated by Matt Wong of the USGS Maui field office.

Discontinued Monitoring Sites

Test Hole A

North Waihee 2

Test Hole E Waiehu

Mokuhau 2

Shaft 33

Other monitoring sites

Historical water levels collected by the Commission on Water Resource Management at Iao Deep Monitor Well

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