The Andros Blue Hole Farm Dispute
A settlement on Andros has 620 residents and one paved road. The island is limestone with a shallow freshwater lens under the settlement, and the water table sits about 2 m below the surface. A developer proposes a 40-hectare pig farm 1.5 km inland of the settlement's wells, on land that drains toward two inland blue holes used for swimming and one small creek. The developer promises 35 permanent jobs and cheap pork for local shops. Residents say the blue holes already turn green each summer and smell of algae. Rainfall is about 1,300 mm a year, falling mostly between June and October, and the land is flat with thin sandy soil over porous rock. The government must decide whether to grant a permit.
1. Explain how the farm could change the freshwater supply and the blue holes, using the physical geography of the site.
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The limestone is porous and the water table is only about 2 m down, so there is very little filtering between the surface and the water people drink. Pig waste contains nitrates and bacteria, and heavy rain in the wet season would wash these down through the thin sandy soil into the lens. Because the farm is uphill of the wells and only 1.5 km away, and groundwater in limestone moves along cracks rather than evenly, contamination could reach the wells quickly. Runoff also drains to the blue holes, so nutrients would feed algae; the residents' report of green water and summer smell is consistent with nutrient enrichment. The blue holes are also connected to seawater through cracks, so pollution is not contained. The farm would need large volumes of water for cleaning and drinking, competing with the settlement's wells and lowering the lens, which in a small island can let salt water move in.
2. The developer says the farm will bring jobs and cheaper food. Weigh these benefits against the risks and recommend a decision.
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The benefits are real but limited: 35 jobs in a settlement of 620 people is about one job per 18 residents, and many would be low-paid and seasonal. Cheap pork helps household budgets, but the settlement depends on its wells and on the blue holes for swimming and possibly fishing and tourism. The risks are hard to reverse: once the lens is contaminated, cleaning it is slow and expensive, and the blue holes are the settlement's main recreation and a possible future income source. A judgement should also note that the developer bears little of the risk if the farm fails or pollutes. A reasonable recommendation is to refuse the permit on this site, or grant it only if it is moved well away from the wells and drainage lines, with lined waste lagoons, a monitored water-testing programme paid for by the developer, and a bond to cover cleanup. The strongest answer recognises that the jobs are certain and small while the pollution risk is uncertain but serious and permanent.
3. Suggest two fieldwork methods the class could use to test whether the residents' claim about the blue holes is correct, and state one limitation of each.
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First, a water-quality survey: take samples at each blue hole and at the creek on the same day each month for three months, measuring nitrate with a test kit, turbidity with a Secchi disc, and temperature, recording results in a table with grid references. Limitation: one class can only sample a few times, so it cannot show whether the green water is seasonal or caused by the farm, and kits are less accurate than laboratory tests. Second, a questionnaire and observation survey: ask 30 residents how the water looked and smelled in each season over the past five years, and photograph the water surface from the same spot each visit. Limitation: memories are unreliable and residents who oppose the farm may exaggerate, so answers may be biased. Together the two methods are stronger than either alone, because the measurements are objective but short-term, while the residents' evidence is long-term but subjective.