Home Page  Back to the Poo page  Let's Be Honest!! About boats, waste, the environment and the law.  A comment by Bob Norson The sewerage discussion has been operating under terms that are more dramatic than scientific and I think it's time to clean that problem up to make the subject more understandable. That is, instead of terms like “harm” or “damage” we should be talking in terms of “change” to environment and proceed from there. Once quantifying the degree of change then perhaps assigning the terms of harm, damage or indeed, benefit can be discussed in a reasonable, instead of hysterical context. To say that any life form can live without creating a change in their immediate environment is nonsense. Whether the change is harmful or beneficial is dependant on the nature of the other life forms you examine, in other words, it's entirely subjective. The new house constructed in the suburbs may appear beautiful to the inhabitants and human passers by but the lorikeets that inhabited the trees that were removed to make way for the house, may feel differently, but then, the people that feed the birds from the new house may counter that loss and create another change that the birds (presumably) find beneficial. Any living thing effects its environment and to use terms like harm are not useful to come to an understanding of the dynamics. With this understanding in place let's look at the marine sewerage discussion. A boat under way offshore…. discharges a load from the toilet. What change to the environment? A litre or so of poo diluted in the sea would be insignificant. Its lack of repetition or volume would preclude any change to the pattern of life below the event. A boat at a popular anchorage…… discharges a load from the toilet. Let's consider the total volume of the water the boat is resting in and compare the volume of the discharge to start. Say your boat is among others with a minimum swing room of 30 metres at a depth of 10 metres. That is a circle of 60 metres diameter by 10 deep. That comes to about 16 million litres of water occupied by your boat. Introducing, say, 3 litres per day of poo to 16 million is not likely to effect a measurable change. A boat in a marina…. discharges a load into its wee bit of water, say, only a few million litres. The material that is discharged is rich in nitrates and phosphates. Even when highly concentrated, these organic nutrients act as fertiliser for aquatic plant life the same as manure will increase the growth of plants on land. As a result, there is more food for the fish.  The benefit continues up the food chain to marine mammals, including fisherman, who are the top predators. Fish and other sea life that consume the nutrient are present because of other changes to their environment, notably, rock walls, pylon and floating jetties that provide a substrate for a variety of sea life. The structures provide a home and shelter and if a discharge is added it enriches an ecosystem that already flourishes. Barring excessive growth such as algae blooms, and/or limited tidal flow, even in a marina, boat sewerage is more an aesthetic issue. (Granted, a serious one!) A town discharges it's sewerage into the sea…….. Now you have some thing. The quantity of discharge involved in a static location finally challenges the sea water to waste ratio. The change to environment is indisputable but what is the change? The nutrient level will encourage everything from sea grass to sharks as the whole food chain gets a boost. A fisherman I got to know down at Tweed Heads told me about how he and his mates used to plan their fishing around the Brisbane city discharge… “Bob, you call it shit but we call it Bream tucker!” Sewerage outfall pipes have been favourite fishing spots for years, remember that your next fish and chips! Now that we discuss town sewerage though, we have to mention other than organic waste as a mix of chemical waste is likely to be present. These chemical wastes present more difficulty because the effects are harder to assess. Agricultural waste (especially herbicides) has had a profound effect on coastal waters and has been evidenced by die off of mangroves (Pioneer river, Mackay) and is found even on outer reefs. In short, what things have people done on the Australian coast that have created changes to the balance that existed before human habitation and then, what are the effects?? Are they harmful?? To whom or what?? To what degree?? What is the cost to mitigate the amount of change relative to the perceived ill effect?? If looked at in a pure and honest sense, anyone expressing the desire to return the coast to “pristine” must first remove the damns that have restricted the natural flow of fresh water unto the coastal waters, outlaw herbicide use all up as it all winds up in coastal waters, remove any artificial structures or man made changes to coastal terrain (canals, sea walls, wharfs etc), the list is endless. An honest assessment and prioritising of goals to achieve an “improvement” (a decrease in change) in coastal waters would be welcomed by the boating community but honesty may have had little to do with the discussion so far.