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PLOS
<br />RESEARCH ARTICLE
<br />Identifying wastewater management
<br />tradeoffs: Costs, nearshore water quality, and
<br />implications for marine coastal ecosystems in
<br />Kona, Hawai'i
<br />Christopher A. Wada'°2, Kimberly M. Burnett 1'2*, Brytne K. Okuhata3, Jade M.
<br />S. Delevaux4, Henrietta Dulai2'3, Ally I. El-Kadi2,3, Veronica Gibson5, Celia Smiths, Leah
<br />L. Bremer',2
<br />°pl 1 University of Hawai'i Economic Research Organization, Honolulu, Hawai'i, United States of America,
<br />2 Water Resources Research Center, University of Hawaii at Manoa, Honolulu, Hawai'i, United States of
<br />America, 3 Department of Earth Sciences, University of Hawai'i at Manoa, Honolulu, Hawaii, United States of
<br />Check for America, 4 The Natural Capital Project, Stanford University, Stanford, California, United States of America,
<br />updates 5 Department of Botany, University of Hawai'i at Manoa, Honolulu, Hawai'i, United States of America
<br />* Ikhuirnett@1hawaiiii.edu
<br />& OPEN ACCESS Abstract
<br />Citation: Wada CA, Burnett KM, Okuhata BK,
<br />Delevaux JMS, Dulai H, EI-Kadi Al, et al. (2021)
<br />Untreated and minimally treated wastewater discharged into the environment have the
<br />Identifying wastewater management tradeoffs:
<br />potential to adversely affect groundwater dependent ecosystems and nearshore marine
<br />Costs, nearshore water quality, and implications for
<br />health. Addressing this issue requires a systems approach that links land use and wastewa-
<br />marine coastal ecosystems in Kona, Hawai'i. PLoS
<br />ONE 16(9): e0257125. httlps://doi.org/101<f11/
<br />ter management decisions to potential impacts on the nearshore marine environment via
<br />jourrnall,pone,0257125
<br />changes in water quality and quantity. To that end, a framework was developed to assess
<br />Editor: Andreas C. Bryhn, Swedish University of
<br />decisions that have cascading effects across multiple elements of the ridge -to -reef system.
<br />Agricultural Science, SWEDEN
<br />In an application to Kona (Hawai'i, USA), eight land use and wastewater management sce-
<br />Received: May28, 2021
<br />narios were evaluated in terms of wastewater system upgrade costs and wastewater related
<br />nutrient loads in groundwater, which eventually discharge to nearshore waters, resulting in
<br />Accepted: August 24, 2021
<br />potential impacts to marine habitat quality. Without any upgrades of cesspools or the exist -
<br />Published: September 8, 2021
<br />ing wastewater treatment plant (WWTP), discharges of nutrients are expected to increase
<br />Peer Review History: PLOS recognizes the
<br />substantially with permitted development, with potential detrimental impacts to the marine
<br />benefits of transparency in the peer review
<br />environment. Results suggest that converting all of the existing cesspools to aerobic treat -
<br />process; therefore, we enable the publication of
<br />all of the content of peer review and author
<br />ment units (ATU) and upgrading the existing WWTP to R-1 quality provide the highest pro -
<br />responses alongside final, published articles. The
<br />tection to nearshore marine habitat at a cost of $569 million in present value terms. Other
<br />editorial history of this article is available here:
<br />wastewater management options were less effective but also less costly. For example, tar-
<br />httlps://doll.orq/10.1S7I/poi.uirnall.pone .0257I25
<br />geted cesspool conversion (a combination of septic and ATU installation) in conjunction with
<br />Copyright: © 2021 Wada et al. This is an open
<br />the WWTP upgrade still provided a substantial reduction in nutrients and potential impacts
<br />access article distributed under the terms of the
<br />to marine habitat quality relative to the present situation at a price point roughly $100 million
<br />C'ireatllve Commons Aitr'iiltu.ution Il..iceiruse, which
<br />permits unrestricted use, distribution, and
<br />less than the entirely ATU option. Of note, results were more sensitive to the inclusion of the
<br />reproduction in any medium, provided the original
<br />WWTP upgrade option than they were to assumptions regarding the efficiency of the cess-
<br />author and source are credited.
<br />pool conversion technologies. The model outputs also suggest that the spatial distribution of
<br />Data Availability Statement: All relevant data are
<br />potential impacts should be carefully considered when comparing different wastewater man -
<br />within the manuscript and its Supporting
<br />agement scenarios. When evaluated separately, the WWTP option reduced total nutrients
<br />iidoirrnatiion files.
<br />PLOS ONE IIhuttlps,//ao!,oir0/iOYI371/jMinnalll.Ipone,0257125 September 8, 2021 1/26
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