Wt At t K - - PowerPoint PPT Presentation

 Wt At  t K H Nt Ht 

Robert Whittier1&2 Adaptive Management Symposium on Groundwater Dependent Ecosystems at Kaloko- Honokhau National Historical Park (KHNHP) November 9, 2018

1 – Hawaii Dept. of Health 2 – Water Resources Research Center

 Wt At

• Coastal groundwater discharge is the primary contaminant

transport vehicle

• Zone of Contribution (ZOC)
• That land area under which groundwater travels to coastal discharge areas
• Activities within the ZOC may contribute contamination to the

Kaloko-Honokhau National Historical Park (KHNHP)

• Delineate the ZOC using a groundwater model
• Inventory the potential contamination sources within the ZOC
• Wastewater disposal has the greatest contamination potential
• Nitrogen isotope data indicate wastewater impact to the KHNHP is not severe

compared to other coastal areas of West Hawaii

tt   Ctt

• Primary Potential Contaminants
• Wastewater disposal
• Light industrial
• USGS sampling
• Found only trace levels of

contaminants

• Data Sources:
• Hunt, 2014, Baseline water-quality

at Kaloko-Honokhau National Historical Park, USGS Scientific Investigations Report 2014-5158, 52 p

• Hawaii Dept. of Health, Safe

Drinking Water Branch Contaminant Data Base

3

4

tt tt Ctt

• Wastewater Sources
• Septic/Cesspool disposal
• Municipal Disposal
• Nitrogen Isotopic Composition of Algae
• Hawaii Coral Reef Initiative, 2013,

Survey of the Nitrogen Isotopic Composition of West Hawaii Coastal Algae

• Potential wastewater contribution when

δ15N >4 o/oo

• Septic/Cesspools within the ZOC
• 2 yr. – 75 septic, 45 cesspools
• 10 yr. – 21 septic, 67 cesspools
• Upland – 53 septic, 82 cesspools
• Total nitrogen load
• 26 kg(N)/d
• Wastewater Disposal
• ~1.5 mgd
• 3.8 mg/L (N)
• Hunt, 2008
• N Load – 20 kg(N)/d
• Likely discharge to the small boat harbor?