Coastal Chemistry Corner: Federally Listed Impaired Waters

Coastal Chemistry Corner: Federally Listed Impaired Waters

It’s time to set the record straight. Dozens of coastal waters in West Hawaiʻi persistently fail to meet federal water quality standards established to sustain and protect aquatic life. Currently, 57 West Hawaiʻi sites are listed as impaired and in need of clean-up according to the Clean Water Act, with an additional 6 new impairments proposed for listing in the State’s latest bi-annual report to the Environmental Protection Agency (EPA) [1]. While most of these areas are deemed safe for swimming according to public health criteria, state and federal law also require upholding water quality standards that will protect coral reef health [2]. But how does this work? What factors tell us if water quality is safe for corals and the thousands of other species that live on our reefs?

Water quality standards for protecting aquatic life are different than those used to protect the public from swimming in water contaminated by sewage. To protect public health, water is tested for the presence of a common gut bacteria called enterococci. High levels of enterococci can indicate fecal contamination—which means a greater chance of illness from swimming in or eating fish harvested from that water. To judge whether water quality is sufficient to protect marine life, average levels of nutrients, chlorophyll, and turbidity measured over time are evaluated against limits established in state law [3]. High levels of these parameters mean that corals are at risk of potentially getting overgrown by turf algae, not receiving enough sunlight to feed and grow, or getting physically smothered by sediment.

Hawaiʻi has also adopted EPA-recommended standards for an additional 58 pollutants that are toxic to marine life including heavy metals, pesticides, and organic compounds [4], but these parameters are not included in the State’s water quality assessment reports. Research has shown that corals are highly sensitive to both regulated pollutants like copper, chlorpyrifos (an insecticide), and anthracene (a combustion byproduct in tar used in pavement sealant), as well as un-regulated chemicals like hormonal birth control, certain pharmaceuticals, and even caffeine.

The ʻĀkoʻakoʻa geoportal now includes a map layer showing water bodies that are included on the Clean Water Act’s 303(d) list of impaired water bodies. Click on a feature in the “Federally Listed Impaired Waters” layer to show which parameters are not attaining the relevant standard and which year that site was first listed as impaired. Although a majority of the assessed sites in West Hawaiʻi have been listed as impaired for more than ten years, they all rank low in the State’s prioritization system for developing clean-up plans in the coming years.

[1] https://health.hawaii.gov/cwb/files/2024/02/IR-2024-public-comment-draft.pdf 

[2] H.A.R §11-54-3 (c) (1) “The uses to be protected in [Class AA] waters are oceanographic research, the support and propagation of shellfish and other marine life, conservation of coral reefs and wilderness areas, compatible recreation, and aesthetic enjoyment.” https://health.hawaii.gov/cwb/hawaii-administrative-rules-har/har-11-54/ 

[3] H.A.R §11-54-6

[4] H.A.R §11-54-4; Appendix E