Some members of our Kailua community don’t like it when Kaelepulu Stream flows into Kailua Bay. They say it’s “stink” water, comes from the sewers, brings plenty kukai into the bay, makes people sick, litters the shoreline with trash, and kills the fish and corals. Fortunately little of this is actually true, but to understand why it’s necessary to understand a few facts and a little bit of the system’s history. This is an extremely abbreviated version of the story.
There have been 9 serious water quality studies of the system since 1992
- 1992 Kailua Bay Study, University of Hawaii
- 2006 Sewage Tracer Study, USGS
- 2008 Stormwater System Survey of Kaelepulu, AECom for the City
- 2012 Total Maximum Daily Load Study, C. Tamaru for DOH
- 2015 Kawainui Flow Restoration Study, Oceanit for DLNR
- 2017 Honolulu City Storm Drain Runoff Survey, Bourke, for ELRA
- 2017 Natural History, Hydrology & Water Quality of Kaelepulu Pond, Bourke
- 2020 Kaelepulu Stream Mouth Water Quality Study, Esibill, MS Thesis
- 2021 Total Maximum Daily Load Study, DOH
None of the above studies found evidence of human sewage pollution or EPA priority pollutants in the Kaelepulu system. None of the above studies found high levels of Enterococcus distributed throughout the system – only occasionally at a few isolated location. Enterococcus bacteria have many non-human sources. Studies by Tamaru and the City found extremely high concentration of enterococcus in storm drains flowing into the system. The study by Esibill showed no correlation between Enterococcus bacteria counts at Kailua Beach and the open or closed condition of the stream mouth.
The Kaelepulu system is an estuary – a mix of about half fresh and half salt water. It is home to two wetlands (Hamakua and Kaelepulu) that are important breeding and foraging habitats for three species of Hawaiian waterbirds on the endangered species list…. and are also are excellent sources of enterococcus bacteria. The estuary serves as a nursery for many species of coral reef fish including kaku (barracuda), ama ama (mullet), awa (milk fish), papio (jacks), lae (silverside), o`opu (goby), seahorses, and others. These fish primarily enter the estuary as eggs and larvae and thrive on the plankton that grows in the pond. Adult fish can be seen migrating back to the ocean on an outflowing current.
The water in an estuary has more nutrients than water in the ocean. This is what feeds the plankton blooms that feed the baby fish and oysters in the system. While this plankton-filled water does reduce visibility when it flows into the bay, the plankton is not harmful to the fish or reef and is in fact a food source for many invertebrates – including corals. What can be dangerous is if too many nutrients are carried into the estuary by storm drains, and the system is not able to handle this large build up. When this occurs the algae and natural bacteria grow too fast resulting in low in oxygen levels and can cause fish die-offs and very polluted water. Nutrient levels (primarily nitrogen and phosphorus) are higher in the estuary than they should be. Samples taken by the City have shown that the storm drains are the primary source of excess nutrients into the estuary. It is important to limit the inflow of nutrients to the estuary, but it is also important to exchange water on a regular basis, to keep the flow of eggs and larvae into the estuary, and the flow of healthy plankton and fish out onto the reef. Think of it like changing the water in a fish bowl weekly – instead of just whenever a fish dies.
Does the system need help? Yes. Low-oxygen events do occur, and the water in the back (Kaha) portion of Kawainui Stream is definitely stagnant. There are six things that need to be done to restore the health of the estuary.
- Open the stream mouth on a lunar monthly basis to assure the exchange of fish, fish larvae, plankton, and water between the bay and the estuary.
- Encourage the City to clean up it’s storm drains
- Enforce building grading controls to keep sediment flows out of the system
- Remove ALL mangroves from the system as these plants crowd out native species and promote poor water quality in Hawaii
- Restore partial flow from Kawainui Marsh to Kawainui Stream to prevent stagnation in the Kawainui Stream and low summer water elevation in the entire system
- Dredge a short section of Kawainui Canal that stops the flow of salt water into the main pond area.
THE NOT SO SHORT VERSION
The Kaelepulu Stream absolutely used to be polluted. Up until about 60 years ago (before the Oneawa canal and Kawainui levee were built) both Kawainui and Kaelepulu drained to the bay at the stream mouth beneath the Lanikai Bridge. Up until 1968 when the levee was completed, there was enough flow from the combined watersheds to keep the stream flowing across Kailua Beach most of the year. But the flow was, by no stretch of anyone’s imagination considered clean. There was no Kailua wastewater treatment plant (WWTP) until 1965 and the sanitary sewers from Olomana flowed directly into Kawainu and from there into Kaelepulu. Even the new development around Enchanted Lake flowed it’s raw sewage into Kaelepulu until well after the WWTP was completed. Up until this time all the other homes in Kailua either used cesspools, or flowed their waste directly into either Kaelepulu or Kawainui Stream. As if that wasn’t enough, the stream flowed directly through the dairy farm in Kailua (present site of Target). During Kona weather the air could be so stink from dairy cow manure at the Kailua High School (now Kailua Intermediate) that classes were often let out early. Enough said.
In 1990 citizens of Kailua were concerned about raw kukai washing up on the beach and the presence of green sand in portions of the beach indicating obvious pollution. They formed a group called Save Our Bays and Beaches (SOBB) and challenged the City to stop the pollution “obviously” coming from the WWTP’s outfall into the bay and onto Kailua Beach. The government responded by hiring scientists from the University of Hawaii to conduct the $5M Kailua Bay Study. The oceanographers (led by H. Krock) concluded that the treated sewage released at a depth of 90-feet from the outfall rarely reached the surface due to mixing from the currents that carried it out and around Mokapu Point. Even during calm Kona conditions the heavy flow of groundwater through Kailua Beach kept surface waters flowing away from the shoreline. Effluent from the WWTP outfall does not impact Kailua Beach.
But what about the flows from Oneawa and Kaelepulu canals? Another scientist (R. Fujioka) found relatively high levels of Enterococcus bacteria in the water, but extremely low counts of Clostridium bacteria. Clostridium is specific to human contamination, whereas Enterococcus has many other sources including rats, cats, mongoose and ducks. Fugioka concluded that Oneawa and Kaelepulu Canals were not polluted by human fecal contamination and that the Enterococcus likely came from the ducks. Subsequent sightings of kukai on the beach turned out to be sea-turtle feces, and the green sand is olivine that becomes exposed when the beach erodes during winter surf.
One acknowledged source of poor water quality in Hawaii is mangroves. They are a non-native invasive species in Hawaii, overgrowing native species habitats, displacing waterfowl, and contributing to poor water quality by blocking the sunlight, and by trapping fine sediments and encouraging bacterial growth on their fine root systems. Historically the City has gone through cycles about every two decades of chopping down the mangroves on the sides of the canals, but not cutting them low enough to kill them and not following up with seed removal to prevent re-growth. So they need to do it again in 10-20 year cycles. In 2002 the ELRA chose to eradicate mangroves from the pond and wetland, and by 2005 had achieved this goal. They then partnered with the Kailua Canoe Club with funding from the Castle Foundation and the Hawaii Community foundation to remove all of the mangrove re-growth from the Kaelepulu Canal between the pond and the beach. This goal was achieved in 2012. The DLNR (who had recently taken over management of the Levee adjacent portion of the Kawainui Stream) let contracts to have all the mangrove removed from the edge of the canal parallel to the levee. The DLNR also removed all of the mangroves fronting the Hamakua Marsh. Heeding pleas from the community the new owners (A&B Properties) of the “Triangle Property” just makai of the Hamakua Bridge removed mature mangroves from both sides of Kawainui Stream below the Hamakua Bridge in 2017. Unfortunately, the City managed portions of the canal, including the 10-foot right-of-way below the Hamakua Bridge, still have mature mangroves that are rapidly re-seeding the Kaelepulu and Kawainui canals.
By the late 1990’s the EPA had convinced the State to get serious about non-point source pollution and demanded that it make a list of all of its surface waters that did not meet state water quality standards. Kaelepulu was not on this initial list. But citizens of Kailua knew that Kaelepulu was having problems with fish die-offs and smelly water and the ensuing deluge of letters to the State convinced DOH to place Kaelepulu on the “303(d) List of Impaired Waters” in 2002. The DOH took two separate actions in response to the listing and citizen’s outcry. They hired the USGS to conduct a study to see if the pollutant source was from human sewage, and they hired a UH professor (R. Babcock, now head of the City’s DFM) to plan a pollutant source study. The 2006 USGS study took samples from 41 locations throughout the estuary and had these analyzed for 71 constituents typically found in sanitary sewer water. The results showed no link between the high nutrient loads in the estuary and any sanitary sewer source.
Meanwhile, the scoping plan (2005) and sample and analyses plan (2006) developed by Babcock followed national guidelines for the development of Total Maximum Daily Load (TMDL) non-point source pollution studies. TMDL studies first try to figure out the quantity of excess pollutant loads in and entering a waterway, where these loads are coming from, and finally come up with a plan to reduce these pollutant loads. The DOH let a contract out in 2006 to follow this plan to take samples from 40 inlets to the estuary and from 40 specific locations scattered across the estuary once a month for a year. These samples were taken in 2009 and 2010 by another UH scientist and aquaculture researcher (C. Tamaru) who wrote up his result in two reports in 2012. The DOH chose not to move forward with the balance of the TMDL study to allocate pollutant loads and load reduction requirements.
In the mean time, however, the City was becoming concerned that the TMDL study was going to hold them responsible for most of the pollutant load reduction. More than ninety-five percent of inflow to the estuary flows through the City’s storm drains, and their drainage permit makes them responsible for these flows. The City conducted a survey of the watershed to better understand where pollutant loads might be coming from and how to reduce these loads, and published these results in 2008. The study concluded that the sources of pollutant loads were likely scattered across the urban landscape, with a few select sites (Enchanted Lakes Shopping Center, drainage channel wall erosion) possibly responsible for more focused pollutant loading. The study recommended controlling these pollutant loads by installing filters at two main drainage channels leading into the pond. Although the City decided not to install the filters on the main drainage canals, they did make improvements to one eroding channel and did install curb inlet filters on approximately 100 (??) of the 800 curb inlet drains in the watershed.
In 2010 a local contractor was developing home lots on a hillside above Kaelepulu Pond. The ELRA was concerned about potential sediment runoff from this development into the pond and attempted to work with the developer, the City, and the DOH to limit any pollution events. During several large rainfalls the ELRA documented runoff events from the development that resulted in large quantities of sediment laden water flowing into the pond. Negotiations between ELRA and the developer resulted in an out-of-court settlement in 2014.
In 2015, using funds from the law suit settlement, the ELRA began planning and permitting to dredge sediments from the mouth of the Kaelepulu Stream where it joins the pond. The study conducted by DLNR (Oceanit, 2015, see below) showed that sediment deposits in this portion of the canal had shallowed it to less than one foot in depth, and that this mound of sediment was blocking the flow of dense saltwater from the ocean to the pond when the stream mouth was open. By dredging to remove this blockage, the circulation between the ocean and the pond should be greatly improved, resulting in increased salinity and improved water quality. This dredging is scheduled for the summer of 2021.
In 2014 the City decided to conduct its own flow and pollutant loading study in the watershed and hired a large environmental engineering firm (AECom) to do the work. The goal of the study was to create a mathematical runoff model of the watershed, and then to use this model to indicate the most efficient way to control pollutant loads. To calibrate the model, flow and pollutant concentration samples were needed from representative storm flows. They installed automated samplers on six representative storm drains and in 2014-15 collected runoff samples from 5 storms. By 2017 they still had not published the result of these studies. The data was obtained (through a freedom of information act request) and analyzed in a report (R. Bourke). Analyses of the results showed that water entering the estuary from storm drains had ammonia nitrogen concentrations 7 times higher, phosphorus concentrations 9 times higher, and nitrate + nitrite concentrations 31 times higher than the concentrations prescribed in the State’s water quality regulations for estuaries. The concentration of enterococcus bacteria was 35 times higher than the level recommended by state standards. The City has (as of 3/21) not yet published its own results from this study.
The DLNR manages the Kawainui levee and the Kawainui Stream adjacent to the levee. They realized that pollutant loading alone would not solve the problem because Kawainui Stream has been essentially stagnant since it was deprived of flow by construction of the levee. In an effort to see if restoration of partial flow, from the marsh to the stream across the levee, would improve water quality, they hired a local engineering firm (Oceanit) to conduct a study and come up with a possible solution. Four large PVC pipes were installed over the levee and water was syphoned from the marsh to Kawainui stream for a period of about 4 months at a rate of about 2 cubic feet per second. Results of the experiment (2015) showed no discernable adverse impacts to Kawainui Marsh and no increased flood threat to Kailua, but significant positive impacts to the Kawainui Stream and Kaelepulu system. The engineers proposed a permanent solution as a below-ground pipe connection between the marsh and Kawainui Stream around the southern end of the levee adjacent to Kailua Road.
In 2018 the DOH decided to re-start the TMDL study with a new sampling effort. They developed their own sampling plan and in 2019-20 collected samples from 16 locations in the Kaelepulu portion of the estuary (non Kawainui stream) every month for 10 months. Their preliminary report compares the samples to the State’s “Stream” water quality standards, not the more stringent “Estuary” standards. But even using the more lenient “stream” standards the waters of Kaelepulu show unacceptably high concentrations of nitrogen, phosphorus, and high turbidity. The data shows that concentration of ammonia nitrogen is 4-times higher, nitrate + nitrite is 2-times, total nitrogen is 3-times, and phosphorus is 2-times higher than allowed by the state water quality standard for estuaries.
So, here we are at the present. What do we know from the above scientific work that has been conducted in the Kaelepulu Estuary?
- There is no sanitary sewer contamination source to the system, with the exception of very rare events that may be due to equipment malfunction or large floods.
- Counts of Enterococcus bacteria are misleading because these bacteria have non-human sources within the estuary including soil, waterfowl, mongoose, cats, dogs, and other animals.
- Whether the stream mouth is open or closed has no impact on enterococcus bacterial counts from the adjacent Kailua Beach.
- Removal of mangroves is beneficial to water quality. While the DLNR, ELRA, A&B Properties, and community groups have been successful removing the bulk of mangroves, the City has not effectively cleared mangroves from areas they manage and seeds from these trees are re-populating the streams.
- The Kawainui branch of the stream is increasingly stagnant at its distal end (Kaha Park) due to lack of flow, with inflow only from storm drains. Increased flow to this segment of stream would improve water quality.
- The estuary has higher nitrogen and phosphorus concentrations than it should. The source of these nutrients is overwhelmingly from the City’s storm drain system. The City appears to be reluctant to publish its storm drain survey or modeling results. Completion of a TMDL study by the DOH should allow the State to require the City to implement actions that will lower or off-set these nutrient loads.
- Improving flow conditions in the estuary by a) dredging the shallow portion of the Kaelepulku Stream, b) restoring partial flow from Kawainui Marsh to Kawainui Stream, and c) opening the stream mouth to flow on a consistent lunar-monthly basis, will improve the water quality and health of the estuary.