Water system connections to be studied

By CHELSEA JENSEN

Stephens Media

A study aimed at defining the interconnectivity between Kona’s high-level and coastal groundwater systems and the possible impacts a connection could have on the area’s hydrologic resources is slated to get under way in May.

Evaluating the degree of connections between the two systems will provide greater insight to planners and the public into the potential impacts of development on potable water resources in the area, according to the proposed study, which will be a joint effort between the U.S. Geological Society and state Department of Land and Natural Resources Commission on Water Resource Management.

These “findings will help to reduce the uncertainty associated with potential impacts from upslope development on coastal groundwater quality and quantity, and, refine our current understanding of the hydrologic flow system,” reads a request submitted by DLNR Chairman William Aila. He also noted it will help establish a better idea of the sustainable yield of the Keauhou aquifer system, which feeds most of Kona.

The proposed study goes before the water resource commission on Wednesday during its monthly meeting held in Honolulu. There, commissioners will vote to provide $95,000 in funding for the study and authorize Aila to enter into an agreement with the USGS for the study, which should wrap up in September 2014.

In all, the 2 1/2-year study is expected to cost $306,000, according to the request. In addition to the state’s share, the USGS will contribute $40,000. The USGS-National Park Service Water-Quality Partnership Program will provide the remainder under a separate agreement.

The study is necessary because the state water resource management commission is required by law to carry out research and investigations into all aspects of water use and quality, according to Hawaii Revised Statutes. State and county planning officials often rely on the information in making decisions related to development.

“This is especially important in areas experiencing development pressures where management decisions depend on an adequate understanding of complex hydrologic systems,” Aila’s submittal reads. “The commission’s determination of sustainable yield is reliant upon having the best available information relating to our ground water resources.”

At issue is whether urban development over, or freshwater withdrawal from, high-level groundwater systems adversely impacts coastal groundwater systems, which support not only area aquatic and cultural resources but also municipal, agricultural, and industrial uses, according to the USGS/DLNR proposal.

The proposed study seeks to evaluate the interconnectivity of the high and coastal level systems and whether water quality and quantity changes in the inland high-level groundwater system can alter the coastal system. It will use chemical and isotopic signatures from a multitude of water samples to aid in making the discrimination, if any, between high- and coastal-level systems.

Previous studies and interpretations, according to the proposal, suggest Kona’s water systems are hydrologically connected. Recently, however, some stockholders, which the proposal doesn’t identify, have claimed the high-level system is not connected with the coastal system — meaning higher elevation activities may not impact lower elevations.

For high-level groundwater, the claim implies that contaminants introduced may not affect coastal resources and any increased withdrawal from the high-level groundwater system won’t affect salinity of the coastal groundwater system, according to the proposal. It also alludes contaminants introduced to the coastal system won’t be diluted by an influx of high-level groundwater and flushing of contaminants will be slower where high-level groundwater doesn’t discharge directly into the coastal system.

The study proposal can be found on the Commission on Water Resource Management’s website at state.hi.us/dlnr/cwrm.