Protecting Our Ocean Waters
Dr. Rick Bennett, Kailua Kona, Hawaii
Hawaii Statewide Conference, Surfrider Foundation
November 14-15, 2009
This brief is intended to give Surfrider members a broad-brush overview of the science-based issues confronting the perpetual need to protect the ocean water quality of the islands. The quality of our ocean water connects all things and all people to the life and economic forces that make Hawai’i .
The hydrology of Hawaii is unique. No other state is similar in many respects. Adding to the complexity, within the islands there are wet and dry sides, and between the islands there is old and new lands and hence soil and soil less regions.
This combination of climates, soils and topography dictates how rainfall water moves on its inevitable flow to the sea. Water is an amazing solvent as most things dissolve into it. Those things that do not dissolve become mixtures. Fast flowing water will carry most all things if the volume and speed is great enough. The vast valleys in the state are testament to the power of water.
The islands are a mixture of dense submarine stone and volcanic rock. Seawater extends through the islands in the labyrinth of tubes, pores and fissures. The rainwater, where is can, infiltrates deeply eventually comes to float on this seawater. The fresh water forms a wedge under the high rainfall areas and flows along this gradient to the sea. Along the Kona coast were there are no perennial streams, as much as 3 million gallons of fresh water emerge in the sea for each mile of coastline every day. On the wetter and more soil dense sides of the islands water has carved surface watersheds that feed from creeks into rivers, that feed water and all it carries into the sea.
The differences in true soil, lava rock and topography between the islands are remarkable. Oahu has vast plains of soil rimmed by mountains that force rain to fall and often quite dramatically. The impetus is to effectively manage surface waters to protect the beneficial uses of this water.
In the low-lying areas, ground water recharge occurs and coincidentally this includes the infiltration of urban, industrial and agricultural pollutants.
On Hawaii Island, the windward side is similar to Oahu yet mostly very rural with many native watersheds. On the Kona side the rainfall belt from 800 to 3000 feet feeds the ground water resource via fast infiltration in highly porous lava soils. Surface stream flows only occur during major storm events. Similar situations occur in sub regions of all the islands.
Important Measurements: Fresh water inputs into the sea can be found in two simple ways. Water temperature will often locate a fresh water flow. Salinity as measured by a salinity or conductivity meter can be especially useful to locate submarine fresh water flows.
SOURCES OF SEA WATER POLLUTANTS
Rainfall and heavy storm flows are the major forces moving our “stuff” and soil sediments to the sea. The faster and straighter it flows the more it will carry. The National Academy of Sciences recently declared storm water from urban areas to be the most important source of water contaminants. Pollution can be predicted based on the acreage of impervious surfaces like rooftops and pavement.
Sediments: Rain and rivers carry soil sediments to the sea. The finer the sediment the longer it remains in suspension. Major rain events in Hawaii are often associated with red seas ringing the islands. Land grading, farm tilling and the like render these fine clay soil sediments free to flow even in light rainfalls. Sediments are a threat to the near shore ecology. Fine sediments are one off, if not the greatest threats to our corals. They simply smoother the coral animals, akin to being buried alive. Additionally sediments can be rich in nutrients like phosphorus and toxics from waste disposal sites.
Important Measurements: Heavy sediments can easily be measure by volume. Fine to very fine sediments are measured by Turbidity instruments or comparator tubes
Our coastal waters are clear azure blue for one good reason; they are nutrient limited or oligotrophic. The surfing beaches of S. California 40 years ago had water that was fairly clear. Today many are shades of brown. The greening of protected embayments in Hawaii is occurring and some beaches like on Maui have had green slimy invasions, rendering them very user-unfriendly. As land is used for homes, farms and most of human activities, the nutrients nitrogen and phosphorus move with rainwater into the sea. There they feed opportunistic algae, previously held in balance by limited nutrients. Algal blooms grow and die fast and can cause depletion oxygen, (eutrophication) smoother and invade algae and then die off to leave a brown scum and make water murky. The USGS estimates that literally tons of these nutrients flow into the sea from human use of the lands. Curbing these land based waste flows must be the highest priority if the living, near coastal waters of Hawaii are to prevail.
Important Measures: The many forms of nitrogen and phosphorus can be measured with fairly sophisticated chemistry. Precise measurements required laboratory based technology. Field test kits typically lack sensitivity and precision. Algal growth can me measured by a component in algae, chlorophyll A. Precise field test instruments are available.
Pathogens: Bacteria, virus and yeast able to cause infections are pathogens. Again, the dose makes the poison. As few as ten GI virus ingested can make you sick. It may take 1000 GI bacteria to get the same impact. Just the same, they get into the sea with water flows both natural and man made. The more time ones spends in the water and the more water that gets into the eyes nose and mouth the greater the risk as well. Surfers according to a recent University of Oregon study ingest about 100 cc of seawater per surfing session, or more likely per powerful wipeout.
The new MRSA Staph is now being found in the ocean and beach sand on about every urban beach tested. It washes of bodies as well as flows with the urban wastewaters. MRSA is a concern for its antibiotic resistance and some strains are very invasive as well.
The risk of infection from ocean recreation is very real, yet we have yet to be able to predict the risk with a high level of confidence. We measure bacteria that might indicate the presence of the real pathogens, yet this association is highly variable. That is to say pathogens, like staph and virus can be present when the indicator bacteria are not and vice versa. As the National Academy of Microbiology said in 1995, the indicator organisms frequently fail to predict and the pathogens of concern need to be measure directly. That step has yet to occur now14 years later.
Important Measures: The direct effect of sewage flows into the sea can be measured by the testing for fecal bacteria, like E. coli, or Enterococci. Some are pathogenic some not. The test requires lab equipment, supplies and expertise. Measuring pathogens is best left to labs equipped and staffed to handle nasty microbes.
Waste water flows to the sea
The not so best selling book, Hydrology of the Hawaiian Islands (2006 UH Press) makes a very clear statement. “(The) coastal waters surrounding the islands will continue to be the ultimate sink for waste waters, either directly or indirectly.” Unfortunately we have a tacit belief the ocean can be our dumpsite and dilution is the solution to pollution. Moreover, ocean disposal is largely out of sight and hence out mind.
Municipal wastewater flows: In the urban parts of the state cities attempt to manage the incredible volumes of wastewater created each day. These flows get to the sea by several means both intentional and indirect.
Spills and leakage: Sewer “spills” occur all the time. Too much flow and it goes over the top. Storm events add storm water to the system by intentional collection or more commonly by very leaky sewer pipes the allow ground and surface water to infiltrate. Infiltration can account for more that 30% of the sewer volumes in many systems. Overflows move untreated sewage and its pathogen loads into the streams and near shore waters. This is so common in Oahu as to give rise to the Brown Water advisories almost always issued after a major rain event.
Ocean “sewage” Outfalls: Pipelines with raw or partially treated sewer or storm water, dumping on top of the sea were common decades ago. It was so smelly and unsightly the public objected vehemently. Yet two major cities, San Diego and Honolulu, still have EPA permits to dump partially treated sewage under the sea. Why because they have some clout and it's the cheapest route. The world’s science on the detrimental impacts are very clear, even though some local marine biologists argue it’s benign or even beneficial. The fact remains, coastal waters globally are heavily impacted by urban affects (PEW Oceans Report 2006) and outfalls are the biggest single source.
Near shore land disposal of treated wastewater under the land, in wells, in pits or sumps does add these waters to the groundwater as it moves to the sea. In Kona and in Kihei the effects are seen and well documented. In some cases the water is disinfected others not as approved by the Department of Health. In either case this water contains large quantities of nutrients that in effect fertilize the algae in the near shore water, greening the water and damaging the corals.
Dry wells: All over the islands counties and developers cut or drill large holes in the ground and nicely covered with a slatted grate. Rain waters from roads, parking lots flow into these dry wells that function as seepage pits to the nearby ground water. Where there are deep fine soils some entrapment occurs. Pits and wells dug into porous lava are fast conduits to ground water and hence the sea. Many mainland communities install systems in dry wells and storm drains to remove the oils and toxics form the storm water.
Injection wells can be shallow or deep and serve to receive wastewaters, rain waters and things as concerning as wastewater from hospitals. The USGS documented the movement of injected wastewater from the Kehei wastewater injection site into the near shore waters. Human markers in the wastewater like pharmaceutical drugs were detected in the sea. Injection wells may be suited for very deep well injection in the interior states of the USA, but such clearly not appropriate for Hawaii.
Agriculture and horticulture, both commercial and the homeowner use fertilizers. We use thousands of pounds annually. The process of fertilizer capture by the plant is far less than 100% efficient. Depending on the plant, its stage of maturity and what form and how the fertilizer is applied, some of it and as much as 70% in some situations, will leach out to ground and surface waters. Good home and farn fertilizer management practices will reduce the need for fertilization and help protect the receiving waters. Due to the impact of nitrogen and phosphorus on the near coastal waters of the world, the day will come when we will add nitrogen to the list of elements we need to limit, like that for carbon dioxide.
The optimal cost, benefit and use for fertilizers remains largely unknown for most of the crop production systems in Hawaii and should be a priority research agenda for university research.
Conclusions: From this brief discussion the opportunity to develop programs and projects and in scale from the back yard to the entire island ecology and more should be more than obvious. Whether its getting the butts and plastics off the beaches or inventing a waterless sewer system, lets do something and build an unstoppable constituency, For the Oceans!