Comments of Richard H. Bennett Ph.D.
Dr. Bennett is Chairman COH
Environmental Management Commission
The following comments are those solely of the author
and not the Commission or other Commissioners
In the early 1990ʻs, the EPA funded construction of the Kealakehe Wastewater Treatment Plant (KWWTP) and finance a reuse project. That reuse project never materialized for the lack of proper planning and programs to promote uses of the reclaimed water for irrigation. The paucity of reuse demand scuttled the EPA required reuse component of the 50 million dollar grant. The failure of reuse necessitated a temporary disposal system that has persisted to this day and now over 20 years. In that time, hundreds of thousand pounds nutrients discharged to tidally influence groundwater flowing into the ocean. The harm is demonstrable as reported by Parsons et al. Now in 2019, the lack of comprehensive reuse and planning elements in the EIS portends a similar outcome, and by default, the valuable water will be discarded in the SAT ponds if sufficient irrigation demand fails to materialize. The current project will reduce the nutrient flux by an estimated 90%, leaving 10% to degrade the EPA Impaired nearshore waters at Honokohau further.
The KWWTP R1 upgrade is a significant improvement and, at last, the county plant will cease being the single largest nutrient ocean pollution source on the Kona Coast. The proposed plan focuses on the need to promote the reuse of high-quality reclaimed water. The high chloride concentration in the reclaimed water will discourage use for irrigated agriculture and most landscape uses. There is no mention in the EIS of any plans or programs to address the severe chloride problem. Sewers along Alii Drive are 20 years old and allowing seawater inflow. Reducing Chloride is fundamental to with adoption of irrigation of reclaimed water.
Another impediment to reuse is the state administrative rules by HDOH that in effect prohibits a private landowner or homeowner from using reclaimed water for business or home landscape irrigation purposes. This rule is not mentioned in the EIS. However, the legislature is considering a bill HR444 that will resolve this shortcoming should it become law.
Maui and Oahu County have provisions in its governance for the management distribution and sale of reclaimed water. The Department of Water Supply for this county appears to have no interest in water reuse management what so ever.
Water processing at KWWTP will go one of two directions, one to the SAT ponds and two to reuse. The path of least resistance, both technically, economically and politically is to the first path. Optimizing water reuse will require a significant marketing effort, financing distribution systems, facilitating proper irrigation management and lastly a policy decision of the county to maximize reuse to help extend the freshwater resource and building climate change resiliency. Leadership along these lines is missing.
The county must prioritize efforts to reduce saltwater infiltration into its sewer lines. The existing lines are very aged and with sea level rise and king tides the water reuse option is placed at significant risk. Sewer line technology that prevents leaks is in use worldwide.
The County of Hawaii in its departments of Water Supply and Environmental Management has no statutory authority to develop water reuse as an income generating activity via voluntary or mandatory reuse districts. Such a program exists in many localities, such as Honolulu. Given the climate uncertainty induced by anthropogenic global warming, institutionalizing water reuse throughout Hawaii County is a serious missed opportunity to create climate change resilience proactively.
Comments in order of occurance in EIS document
1. The second paragraph mentions a landscaped buffer strip at the KWWTP to be irrigated
a. The Director reported this feature had been eliminated
b. Recommend it be reinstituted for its teaching and demonstration value as well as a safety buffer should there be excess R1 irrigation water
i. Note: The project will produce two qualities of water. Merely calling them R1 and R2 is confusing and will hamper the public understanding. This needs to be clarified in the document preface and elsewhere as well as for public education.
a. The plans by Kohanaiki Golf course should be addressed elsewhere. If not more detailed is needed.
b. Significant Beneficial and Adverse Impacts
Construction and operation of the proposed improvements are expected to significantly reduce the
mass of nutrients, primarily nitrogen and phosphorus, which percolates to the groundwater when
compared to the current amount discharged to the existing percolation basin. The nutrient mass
reductions will be achieved via the combination of water recycling, the subsurface flow
constructed wetlands, and the SAT system. The existing percolation basin will be closed as part
of the project. This paragraph is not clear. What constitutes significant? If the plan reduces nutrients for the SAT discharged water by 80-90%, it should so state. It implies the nutrients will percolate to groundwater. It should be made clear that the groundwater is tidally influenced brackish water that flows to and from the sea with a net discharge into the harbor at about 3.16 MGD (Honokohau Harbor Peterson et al. 2017).
The authors have not seen the Sump at Kealakehe in past or present operation. It is a rock filled drain and not a percolation basin. The water flows to one corner of the basin and thus does not perform as a percolation basin. In effect, it is behaving more like an injection well where the drain site is deeper than it is wide.
The use of the term R1 upgrade benefits is misleading. The R1 water for irrigation will be different for that disposed in the SAT ponds. Again the terminology will be confusing to a public that needs to understand what is being treated and how it is used or disposed.
S-3: Paragraph refers to a "basal groundwater lens."
At an elevation of about 80 feet and three-quarters of a mile to the coastline, the groundwater below is an "underground estuary" (UH hydrologists Glenn, Peterson, and others) that rises and falls with the tides. There is no freshwater lens in the nearshore regions of the island as there are in water well locations well inland.
This section recognizes that "groundwater" enters the ocean. The underground estuary is part of the ocean. This again suggests a misconception island hydrology even though the definitive text by Mink and Lau has been in print since 2006. This is a critical distinction, as this "hydrologic connection" has profound implications under the Clean Water Act and it is anticipated that by 2020 SCOTUS will have made a final determination. Regardless of the outcome, it is more than prudent to manage the project in the public interest as required by the Hawaii Constitution Article 11,
“All public natural resources are held in trust by the State for the benefit of the people."
a. The documents state that the KWWTP produces 1.7 mgd to the Secondary Treatment Classification. HDOH does not use this terminology. Secondary per most states implies a prescribed level of disinfection. The current water is not disinfected to R2 Standards. If fact HDOH required no disinfection for "sump" disposal and they may not require it for SAT disposal, and this deficiency needs to be addressed. It is possible that the wetlands and SAT treatment will disinfect adequately, but that remains to be confirmed. This is especially true since most of the groundwater that will convey the SAT water flows into Honokohau Harbor thus increasing the risk of human exposure.
b. I-5: state the chloride content ie, the salt will limit the R1 water to "salt tolerant" vegetation and provides no perspective as to the minimal options of salt tolerant plants. Practically speaking the degree of salt tolerance is only found in one or two grass species. Thus in the current state, the water will have minimal landscape and agricultural applications. The chloride levels present a risk that could functionally kill commercial community interest is water reuse.
i. This problem needs much more explanation for the sake of full disclosure and transparency
ii. HAR 11-62 (1) needs to be more fully addressed as nutrients and pathogens in SAT leachate could violate the statute
iii. HAR 11-62 (7) Consistent with the Stateʻs administration of the NPDES
1. In light of the 9th Circuit Courts Decision and supporting appeals the state failed to administer the CWA NPDES with Maui County properly and will do so again relative to the SAT Ponds draining to the Waters of the United States
c. 1.7 Objectives
i. Mentions “ reduce the nutrient load to the disposal system." What is the disposal system? The ultimate repository of wastewater is the nearshore ocean, (Mink and Lau 2006 Hydrology of the Hawaiian Islands p.234 )
The combination of treatment through the subsurface
wetlands system at the WWTP and the SAT system will significantly improve upon the current percolation disposal basin method of effluent disposal
The current sump that has been a de facto injection well is an atrocious and unregulated disposal pit that is perhaps the least costly system in use anywhere in the United States. Over the 20 years of operation, hundreds of thousand pounds of nitrogen and phosphorus have flowed via the underground estuary into the sea. The waters of Honokohau are listed as Impaired under section 303 D of the CWA (Clean Water Act). Virtually any modern wastewater treatment and disposal system would be an extreme improvement just because the status quo is so egregiously poor, unpermitted and hence unlawful.
Figure 2.1 At the junction after the covered lagoon box is a valve of sorts. Nowhere in the EIS is there an economic or policy discussion of the forces that will influence which direction the water will be sent. If this project is really about advancing reuse then much more disclosure is essential. Policy and investment decisions will make or break reuse and that discussion and decisions greatly influence the environmental and economic impacts of this project.
2.1.1 5) Refers to HDOH Guideline for UV disinfection. There are several options in the guidelines which will be employed. It is highly recommended that the viral inactivation guideline is applied since the health threat in sewage is viral, not bacterial.
2.1.1 10) The monitoring of wetlands performance is not mentioned. What are the performance guidelines for nitrogen? If the treatment is outside of performance guidelines what is the sensitivity of detection? It states a 90% reduction in virus and bacteria. Which virus and which bacteria? 90% is only two log reduction and not worth mentioning. Overall a 5 log reduction is most desirable.
2.1.3 13) “The combination of polishing through the subsurface flow wetlands and the additional natural processes occurring through the SAT system will ensure that the highly treated effluent is safely returned to the environment." Safely in this context is without definition and used more like a marketing term than any verifiable impact on human health.
There is full body contact with the water in Honokohau Harbor and Beach since the minimum infective dose for the enteric virus is extremely low, we need to evaluate the extent to which human enteric virus are or are not present in the SAT leachate. There is no data to support speculation about safety.
“The SAT system concept is to apply the polished effluent over a large area intermittently and then allow it to trickle through permeable soils or sands, then into the native soils beneath the site. As the effluent percolates through the engineered sand and soil matrix, it is treated by physical filtration and by natural biological and chemical mechanisms”.
Most people familiar with the proposed SAT pond site recognize there is no native soil here. It is fractured A‘a, Pahoehoe, and basalt. It is exceptionally porous with instant and infinite drainage capacity.
The public is entitled to know what the natural and chemical mechanisms are and how effective they remain in the future.
Volunteer vegetation can be allowed to grow on the SAT surface. That decision may need to be reevaluated as plants like the invasive Fountain Grass may make SAT pond less functional by interfering with water movement. As deeper rooted weeds dye it may create water channelization. Wet-dry cycles may kill weed mass and present a fire risk that could damage SAT pond features.
2.2 Buffer Parcel Irrigation, already addressed
2.4.3 “The anticipated high salinity of the recycled water effluent from the Kealakehe WWTP means that the landscape irrigation areas will be restricted to salt-tolerant grass and plants. Salt-tolerant species of grass include seashore paspalum (Paspalum vaginatum) or Bermuda grass (Cynodon dactylon). Preliminary plans show a total of about 21.9 acres of planted areas within the park will be removed and replaced with the salt tolerant plant materials. The replacement R-1 recycled water irrigation system will service these areas.
Which plants are salt tolerant? The park has many plants currently growing, and they are at risk if the R1 water is used on them.
The area essentially gets no rainfall; thus irrigation in a high ET area will need to provide all the water and if the water is applied contained by the ETo, ETc the risk of increasing salts in the root zone is real. There is no mention of the plan to manage salts in the root zone. One technique is to over-irrigate to "rinse" salts below the root zone. The fertilizer nutrient Nitrate is one of those salts. Such salt movement could impact the subsurface estuary.
3.3 The State of Hawaiʻi DOH regulates wastewater discharges. Initial discussions with
the DOH has indicated that the Kealakehe WWTP SAT system would be regulated as
land disposal, as set forth in the requirements contained in HAR 11-62. HAR 11-62
Regulations require secondary treatment (BOD5 and TSS less than 30 mg/L) prior to
land disposal and establishes minimum monitoring, record-keeping, and reporting
requirements. The treated effluent from the Kealakehe WWTP discharged to the SAT
basins will be of better quality than the minimum requirements for land disposal.
However, the SAT ponds very near the shore are unique to Hawaii and unique to the mainland USA. In the vast majority of cases SAT ponds or aquifer recharge basins are constructed over deep alluvial soils. The Hawaii Department of Health Wastewater Branch has no experience with SAT pond design or operation and their land application rules may or may not be appropriate. Like it or not this is an EXPERIMENT and as such should require a high degree of monitoring supervision. The WWB does not have the staff expertise or the budget to play this role. The County is advised to avoid the pitfall of relying on the HDOH for appropriate guidance as they have in the past. Recall it is the HDOH that has looked the other way relative to the sump use for over 20 years. People are likely once again to say we are doing what the state has told us what to do. That might be acceptable if the state has experience and expertise. Perhaps it would be wise to consult with the Southern California Water Quality Control Board to get their recommendations on how to operate and monitor the project. The San Gabriel River SAT system ultimately drains to the ocean near Seal Beach Ca. To default to the HDOH, with technical expertise oversight would be a grave error.
3.5 Ground Water
“No significant adverse impacts to groundwater resources are anticipated from
construction and operation of the proposed improvements”.
It is good that we finally stop polluting the underground estuary and the sea from two decades of unlawful wastewater disposal but saying there is no significant impact to groundwater is looking at the situation through a straw. First, it is not groundwater, it is an underground estuary that communicates with the ocean subject to each tide, four times a day. The estuary and the groundwater many thousand feet inland are laden with nutrients from human activities. Thus the water under the SAT ponds and at the irrigation sites already has a nutrient burden that has Impaired and is Impairing (CWA 303 (D) the entire coast of West Hawaii. As we will show in the B and W section of the EIS, there are scenarios where the SAT ponds will add additional nitrogen to the estuary. Calculations reveal in one scenario about 10% of the Nitrogen flowing into the harbor will arise from SAT pond percolation and thus further impairing the waters of the United States. Under the CWA further degradation is not permitted in Impaired Waters. The law requires remediation via a TMDL. By the decisions of HDOH, there are no TMDLʻs on the island for any of the 58 impaired ocean sites. One of those sites is Honokohau Beach, and it is listed for excess nitrogen, phosphorus, ammonia, and turbidity. Few other sites have so many violative analytes. The combination of the County operated restrooms, private cesspits, and the wastewater flows from the KWWTP sump contribute to this degradation of the marine waters. The failure to indicate the need to obtain an NPDES permit for the SAT ponds is a serious oversight. Whether or not HDOH will require a NPDES and they are doubtful to require it, the COH being dutiful of Article XI of the Constitution should obtain a NPDES permit.
3.5 Impacts and Mitigation Measures
“The R-1 Upgrade project will allow a portion of the recycled water to be put to beneficial
use. Nutrients present in the recycled water will be distributed over the areas that are
irrigated. The applied nutrients will then take up by the plant material as fertilizer or
immobilized in the soil. Over-application of nitrogen via recycled water application
represents a risk to the environment; therefore the amount of nitrogen applied via
recycled water should not exceed the needs of the vegetation as applied. Applied
phosphorus is generally taken up by the crop or adsorbed to soil particles and
represents less environmental risk so long as recycled water is applied at appropriate
rates to prevent runoff to surface water”.
This statement is an over generalization. All water and fertilizer requirements are a function of the type of plant, the soils, climate, and type of fertilizer used. No plant is 100% efficient in the uptake of fertilizers no matter how they are applied. There will always be leachate N. The golf turfgrass industry has studied this extensively and in particular at UC Riverside. If we are to do reuse correctly, we must get specific and sophisticated. To suggest limiting water applied to not overfertilize is a prescription for disaster. Plants under irrigated will wilt and be stunted. Plants in this condition look very poor and stop using water and nutrients. This type of mismanagement has plagued the early adopter of reuse for irrigation over 30 years ago. We need not have to reinvent proper irrigation and fertilization. A consulting agronomist with irrigation expertise should have a significant role in the COH irrigation management team. In the interviews, we conducted with the consultants these issues were raised and still they failed to be recognized as sufficient to be discussed in the EIS.
SAT pond phosphorus removal efficacy will be discussed in the B and C part to the document.
“Each SAT basin will be equipped with a pan lysimeter that will allow the collection of
subsurface drainage samples. A lysimeter monitoring program will be developed in
conjunction with DOH to monitor the SAT system’s performance. Semi-annual
sampling for nutrients, salts, and other parameters developed in consultation with DOH
To restate the obvious, the SAT ponds in lava rock is an experiment and a real-world trial. Monitoring with guidance from the experts in California should be developed and then proposed to HDOH. We cannot rely on their opinions; we need expertise.
Initially, lysimeter monitoring for nutrients, pathogens, PPCRʻs should occur bimonthly for the first year and the quarterly until the data variance established. If data does not normalize more intense monitoring and testing is needed to understand the erratic performance.
3.6 Coastal Waters
The coastal waters are the waters of the United States and the state of Hawaii. Why the Clean Water Act regulations are not mentioned in the EIS is most troubling. As shown in the HDOH State report to the EPA, the waters of Honokohau and north are impaired and as such invokes the provision of the CWA that require mitigation. One of those requirements is that no further impairment is allowed. To know that an NPDES permit is required. It may show that the impacts from the SAT leachate to the estuary do not materially further impair the marine waters. That, however, cannot be left to speculation and wistful assurances in an EIS.
The Federal Courts have ruled and upheld that wastewater injection wells polluting groundwater moving into the sea is a CWA violation. The flows represent a point source discharge for which a NPDES permit is required
For the state's disregard for marine water quality on Hawaii Island, there is not a single TMDL for any of the 58 Impaired Marine Water Bodies on the island. The County of Hawaii must not default to the state's ignorance and do what is right. A TMDL for the waters of Honokohau may well show that the lessor nutrient additions in the watershed do not significantly further degrade the receiving water. Absent the investigation and calculations it is unwise to assume as we have no idea at what point and additional nutrient addition tips the balance and massive phytoplankton and Ulva growth may occur as has occurred on Maui. The consequences are dire environmentally and economically and must not be left to blind hope.
§ 130.7 Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.
(ii) TMDLs shall be established for all pollutants preventing or expected to prevent attainment of water quality standards as identified pursuant to paragraph (b)(1) of this section. Calculations to establish TMDLs shall be subject to public review as defined in the State CPP.
Administrative rules and not the HRS governs the waters of the state. The EIS is correct that the Kona Coast is AA Marine Waters and paradoxically most of those water are EPA listed as “Impaired." Thus the goal of HAR 11-54 is boilerplate folly. The HAR does have numeric water quality standards. These standard are violated regularly and for years without consequence. This categorical inattention to ocean water quality shifts the accountability to the County of Hawaii to voluntarily execute an NPDES permit for any discharge to subterranean waters.
Special Culture Concern
Table 3-2 is culturally inappropriate. It uses the term RACE. There is no scientific basis for such a term. The term ethnicity is more appropriate. However WHITE is not an ethnicity. The table also inappropriately groups African American with Native American and Native Alaskans as one class.
Brown and Caldwell Technical Report
The concluding paragraph implies that the current and future discharges from the SAT ponds only impact the groundwater. The water under the region is a mixed brackish underground estuary that is significantly tidal and wave influenced and as is "hydrologically connected" to the sea. The use of the term groundwater fails to convey the connection to the sea promoting a false understanding of the island's hydrology in the public mind.
The section does not fully explain the seriousness of high chlorides. The options for salt tolerant plants is limited. This UH publication provides a more comprehensive listing of salt tolerant plants. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/l-13.pdf
The report should identify why chlorides are a problem for WWTP R1 upgrade and how they can be controlled at the source.
The Stateʻs use of Fecal Coliform Indicator can no longer be scientifically justified. Even for drinking water, the fecal coliform test fails to assure safety. Therefore the bacteriophage standard is the appropriate metric for UV disinfection efficacy.
5.0 Water Transmission
There is no discussion of sewer and reclaimed water lines providing service to the Honokohau Harbor. Sewering the Harbor would be an effective mitigation for some of the nutrient loading in the harbor waters. There is a significant need for landscape irrigation at the harbor as well.
6.3 Irrigation System
Solid set sprinkler systems in use by water reuse agencies have historically been poorly designed. Typically the spray overlap is insufficient, and large areas are under irrigated. In table 6-1 there is no mention of “uniformity of distribution” and how it is calculated. This concern applies to the Old Airport system as well.
Sprinkler distribution uniformity is critical for both water and nutrient management. See http://www.irrigationtoolbox.com/ReferenceDocuments/TechnicalPapers/IA/2004/IA04-1120.pdf
6.3.2 Nutrient Management
The N recommendations from the Hawaii seed supplier are excessive. University and US Golf Association N fertilization rates for grass is .5 to 3 pounds per 1000 sq ft.
The potential for over fertilization needs to be reconciled in the report.
8.1 Constructed Wetlands
The uses of wetlands are to be recognized and celebrated as a significant advance for Hawaii County. The suggestion to use wetlands was made over 20 years ago and summarily dismissed as unfeasible. It is encouraging that constructed wetlands now recognized as essential components of wastewater treatment.
How will the treatment efficacy of the wetlands be monitored in term of frequency and analytes? What are the plans for vegetation management in the wetlands or is overgrowth a threat to wetlands plant viability? What level of salinity in the wastewater impairs wetlands viability and processing?
188.8.131.52 Pathogen Removal
Ninty percent removal is only a two log reduction, yet it may complement the subsequent treatment in the SAT ponds. Ultimately the actual reduction in the leachate needs to be objectively determined. The lack of an HDOH requirement for same does not obviate the needs for accountability as the leachate will impact nearby recreation waters.
In addition to documenting pathogen removal, the ability of the constructed wetlands to remove pharmaceuticals and personal care products needs to be determined and operational option evaluated. Priority operational conditions should prioritize nutrient removal, pathogen removal and PPCP removal in that order of importance.
8.0 SAT Ponds
SAT ponds are widely used in the mainland USA and most always constructed over deep soils over an aquifer hundred or more feet below. The use of SAT in coastal volcanic basalt Hawaiian Islands is a first.
As of the release of this EIS the details of phosphorus adsorption in "Blue Rock" sand has not been provided. Needed is a working model estimate of P adsorption capacity and adsorption efficiency over time. At what point of decreased adsorption and release of increasing P in the leachate require the substrate to be refreshed?
The issue of pharmaceuticals and personal care product (PPCP) chemicals in the wastewater for SAT discharge and irrigation is not addressed in the EIS. There are a few reports of degradation of PPCPʻs in SAT processing and should be included in the EIS, Moreover, testing of the same should be conducted on the SAT leachate. As reported this year, anaerobic processes at the wastewater treatment process can transform PPCPʻs into more bioactive compounds. These issues may impact water reuse. For the ocean, the potential of PPCPʻs to affect the coral reef just outside of the harbor needs to be addressed.
Reports suggest that actual performance of any wetlands or SAT ponds are, and generalizations are not adequate to predict treatment performance for PPCP removal.
8.2.5 SAT Monitoring
Monitoring this near-coastal volcanic SAT Pond is critical. However, semiannual testing is not adequate to monitor an experimental operation. Over the first two years, monitoring should be bi-monthly. The data will be provided to the Director of DEM, who in turn shall provide the data to the EMC for their review and recommendations. The HDOH has only one hydrologist on staff in the Clean Water Branch. That hydrologist has no expertise in SAT systems and as such may not be in a position to evaluate and respond to data in a timely and open manner.
9.1 Nutrient Reduction
The sump at Kealakehe is a regulatory aberration that has allowed for 2.3 million pounds of nitrogen to be discharged into the subterranean estuary over the last 20 years. It has been the single largest point source of nutrient pollution into the AA Pristine Waters of the Kona Coast. Any improvement, albeit long overdue, is most welcome. However, a 90% reduction over the next twenty years still conveys between 102000 and 2M pounds of N to the estuary below. Not accounted for in this EIS is N that leaches to the subterranean waters below the lands irrigated with N containing reclaimed water.
9.2.1 Water Recycling
Let there be no mistake that water reuse is critical to the water resource future of all the islands. The challenge will be how to manage it well.
This section is far to vague on how best to manage such irrigation. Far more detail is needed on nutrient management and how it comports to water management that contains salts from seawater contamination of sewage. Fertilizers, both phosphates, and nitrates are also salts. For example, mowing grass and allowing it to stay on the land recycles nitrogen and thus soil nitrogen levels need to be determined to inform the adjustment of N levels applied. The grass system has a finite capacity to utilize both N and P.
The assumptions in table 9-3 are unrealistic, and the prescribe fertilization rate is very excessive for a low biomass production rate grass. It would be advisable to consult with the turfgrass experts that serve the golf courses of the island.
Initially, reclaimed water will be utilized at the Old Airport and adjacent recreation area. As can be seen today water management by COH Parks and Recreation leaves much to be desired. It is highly recommended that the COH retain professional irrigation agronomists to advise and monitor irrigation and fertilization management (Agronomic Practices Appendix B).
9.3 Nutrient Reduction Benefits
Certainly any effort to limit nutrient flows into the marine environment is to be lauded. The overnutrition of AA Pristine Kona Coast waters is occurring and causing broad scale shift in the marine ecosystem including promoting phytoplankton and damaging the corals. Algal biomass production in most nearshore Hawaiian water is increasing, and the isotopic N 15 concentration points to anthropogenic nitrogen.
The golf course at Kohanaiki is currently irrigated and fertilized and appears to be adequate. Even in its mature state, golf courses are known to leach nutrients to the nearby receiving waters. The anchialine ponds at Kohanaiki have been and continue to be nutrient-laden(Appendix A). The water level in the ponds rise and fall with the tides establishing a hydrologic connection to the sea. The nearshore waters are EPA listed as impaired for nutrients. There is reasonable scientific certainty that at least some of the nutrients are leaching from the nearby irrigated lands.
As the commercial entity at Kohanaiki uses the COH R1 water that may well contain 15mg N per liter, one may assume they now bear the responsibility to manage the water and the nutrients in a manner that minimizes nutrient leaching to the ponds and the sea. This responsibility is not mentioned in the EIS. The COH would be wise and prudent to transfer the accountability to the user contractually if that is allowable by state and federal law. Otherwise, the COH must maintain a level of management oversight and control to assure that excessive leaching of nutrients does not occur.
Hydrologists have measured water flows at the headwall of Honokohau Harbor. The estimate based on Radon isotope measurements indicate the 12,000 cubic meters of brackish water flow through the walls into the harbor each day. That equates to 3.16 million gallons per day. Test wells just West of Quee Kahamanu Highway and well North of the SUMP contain 1183 micrograms TDN per liter. Assuming the brackish water at the harbor is of the same watershed, this equates to 312 pounds of N per day into the harbor and then out to sea as documented by UH researchers (Appendix C, D, E)
Table 9-5 proposes five scenarios and predicts the mass of nutrients released to the environment. What is not clear is what proportion is disposed of by irrigation and what proportion leaches through the SAT ponds. In scenario 3, 32 pounds of N are released into the subterranean estuary and add to the N in the water from other human activities.
This observation once again argues for the need for a TMDL for the watershed to identify the primary sources. Given the lower concentration of 32 pounds per day we can hope it is a lessor contributor but absent a TMDL we can only speculate.
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