• A Rinconvenient Truth

The Land-Sea Connection: the watershed under your feet that deserves attention now

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Recently, we reported about the beauty in our backyard to expose you to the natural resources – specifically the coral reefs - currently under protection in the Tres Palmas Marine Reserve. But the ocean and the land are intimately connected, especially on an island. Therefore, it is also important that we understand how our land-based activities affect our ocean ecosystems.


For example, coastal development can damage our natural resources through sediment run-off. This occurs when heavy rains wash away topsoil, or dirt, from construction sites. This type of activity has been observed in Rincón, most recently in 2019, when the orange dirt-filled waters from hillside development in Ensenada formed a river down the marina road and ended up in the ocean. Unfortunately, this sedimentation does more than just muddy up the swimming spot. Sedimentation can smother coral reefs, blocking their ability to eat and grow, which eventually leads to death – and is certainly counterproductive to the protection of the coral reef at Tres Palmas. Consequently, we must also discuss the natural resources below our feet – our watersheds – in conjunction with what’s below the waves. So, what is a watershed?



A watershed is essentially an area of land on which all water that flows over it, or under it, eventually drains to the same place (such as a river or bay) before emptying into a larger body of water, like an ocean. The northwest coast sits atop two main watersheds, the Rio Grande de Añasco and the Rio Culebrinas (Aguada). Neither of these watersheds’ rivers directly originate in Rincón, however the Rio Grande de Añasco watershed does encompass the land area of the municipality and both watersheds can directly impact our coastal resources.




Map of the two main watersheds for the west coast, from nrcs.usda.gov

The Rio Grande de Añasco empties one of the island’s largest watersheds into the Mayagüez Bay, encompassing over 257 square miles. This watershed is considered impaired by the Natural Resources Conservation Service, which is part of the United States Dept. of Agriculture, due to its exposure to harmful chemicals like pesticides, fertilizers and manures from the pasture lands alongside the river. Those harmful chemicals leech into the soils, or directly into the rivers, and can even join up with the water supply or work their way down to the ocean. That means we are overloading our water sources with bacteria (E. coli, from leaky sewage systems and animal waste), and excess nutrients like phosphorus and nitrogen from fertilizers. The Rio Culebrinas watershed is directly north of Rincón, thus outflow from this river can be observed in the ocean when currents are moving south from Aguada.


There is also a microgrid of natural drainages within Rincón, especially within the area surrounding the Tres Palmas Marine Reserve. These natural channels are responsible for directing water from the hillsides down into the ocean. Many of these streams are temporary, only activated during periods of heavy rainfall, but nonetheless contribute to the sedimentation that is transported seaward. Additionally, the limestone composition of the northwest coast makes it particularly susceptible to erosion. This type of topography – known as karst – is composed of the dissolution of limestone made up of the shells and skeletal remains of marine organisms. The karst creates underground caves and drainages to direct water in the subterranean, but it also makes it difficult to build as limestone is quicker to erode than non-sedimentary rocks like granite.

Micro-watershed system in Ensenada, developed by Michael Moul

On an island, every river essentially leads to the ocean, so we must be careful about what we introduce to those water sources AND reduce our impact on the land elsewhere in the watershed (i.e. not directly next to a river). It is important to manage and protect entire watershed systems rather than solely a river, a lake or another water source within the watershed. Since land and sea are connected, this strategy allows for a more comprehensive management scenario.





There are ways that we can protect our watersheds and thus simultaneously protect our water sources, like our oceans and our own drinking supply.

  1. Plant native hardy plants in your yard or garden that do not require frequent fertilizing

  2. Switch to organic fertilizer, or use compost as a means to fertilize.

  3. Recycle yard waste and food scrap waste into a compost. Not sure how to get started? Here is an easy trash can compost DIY that requires few materials.

  4. Use less water in your house while brushing your teeth or cleaning dishes. Take shorter showers and fix leaky faucets or drains to conserve water. We are all drinking water from the same supply, so be a kind neighbor and leave some for others.

  5. Check your septic! Make sure you don’t have any leaks, especially if you live directly by the water. This may require the assistance of a qualified professional.

  6. Do NOT pour toxic chemicals down your drain and refrain from cleaning the exterior of your home with toxic chemicals.

  7. Consider making your driveway or walkways out of gravel or stones that allow waters to soak in rather than runoff.

  8. Make sure ANY development, land movement, or building that you are proposing to construct at your house is properly permitted, researched and impacts are mitigated. DO NOT assume you have the right to do this without a permit and without proper measures in place to prevent sedimentation and pollution from draining into the streets and ocean.



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