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Assessing Threats to Costa Rica's Aquifers and Water Security

The historical situation of the growing dilemma of Costa Rica's aquifers and the imminent threat of contamination of drinking water sources


Understanding the Dual Challenge of Water Quantity and Quality in Costa Rica's Aquifers


Just over 110 km³ of water is renewed annually in Costa Rica; 73 km³ is surface runoff, while 37 km³ (33.75%) naturally recharges the aquifers. 34 of the nation's 58 aquifers are coastal, nine are continental volcanic, and fifteen are continental sedimentary. If all of Costa Rica's water—from lakes, rivers, reservoirs, and aquifers—could be divided among its people, each individual would get approximately 24,873 m³ per year.


Underground sources provide 70% of drinking water, making their protection crucial. A thorough assessment is needed to understand factors like recharge, extraction, availability, current state, threats, and regional vulnerabilities. This will enable the zoning of safe activities within the area. We must also consider the possibility of climate change reducing precipitation in some areas, negatively impacting aquifer recharge.


There is ample evidence of widespread aquifer contamination in Costa Rica, and this will only increase as more cases come to light. Systematic studies of these subsurface water deposits, conducted by either academia or water management organizations, are crucial to revealing the true extent of the problem.


The Guanacaste coastal zone has seen evidence of saline intrusion since the early 1990s. Analysts report that the coastal Flamingo aquifer, subject to significant tourism and real estate development, has been overexploited, leading to the salinization of wells and requiring relocation further inland. Similar threats are evident in Coco, Brasilito, and several other coastal areas, leading to well closures and sporadic salinity spikes during dry seasons.


In the Central Valley, the Barba aquifer's water quality has been under siege for decades due to human activity. Since the late 1990s, Agrotec Analytical Laboratories has documented seasonal contamination with various pollutants in numerous wells. Environmental monitoring wells associated with the new international airport project have also consistently tested positive for contaminants, raising concerns for the densely populated region.   While most cases go unnoticed, the Barreal de Heredia case, where well AB-1089 was found heavily contaminated with diesel exceeding safe limits, underscores the severity of the issue.


Both urban expansion and agricultural practices significantly impact aquifer health. Studies highlight the threat posed by current coffee fertilization practices and the lack of proper wastewater disposal systems in rapidly urbanizing areas. Similar concerns exist in agricultural regions of the Caribbean, which are already facing controversies over organic compound contamination linked to their production systems.


Examining Threats to Costa Rica's Groundwater Quality and Sustainability


In 2008, governmental studies commissioned by the Ministry of Environment (MINAE) reported that nitrate levels in several aquifers, including Barba and Colima, are projected to exceed the safety limit (50 mg/l) in the coming years.  These crucial aquifers, supplying drinking water to Heredia and San José, face potential depletion within 15 years without proper measures.


Researchers have been calling out a concerning imbalance: water extraction from the Barba and Colima aquifers (9,870 liters per second) exceeded their recharge rate (9,720 liters per second).  This necessitates immediate action, like installing well flow meters and reassessing extraction quotas, to protect this vital resource.


In the Caribbean and Northern regions, pesticides used on banana and pineapple crops contaminate groundwater. A study by Ruepert (cited in the State of the Nation) found alarming levels of contamination: 10% of the sampled wells contained pesticide residues, mainly the herbicide Bromacil, which is used in pineapple cultivation. Additionally, a concerning 62% of wells exceeded the safe nitrate limit (5 mg/l).


Since 2008, researchers have reported on the alarming contamination of groundwater in Limón province, particularly near the Costa Rican Oil Refinery in Moín. Investigations revealed the presence of hydrocarbons exceeding the national drinking water standard, posing a significant threat to public health.


Enforcing Comprehensive Governance for Sustainable Management of Costa Rica's Aquifers


Given the evidence of its impact on Costa Rica's aquifers, detailed studies are essential. The Ministry of Environment, Energy, and Telecommunications, the National Service of Groundwater, Irrigation, and Drainage, and the Costa Rican Institute of Aqueducts and Sewers should all be involved in carrying out these studies.


Municipalities must base territorial development on knowledge of regional hydrology and collaborate with local governments to share basins and aquifers. Water management requires a vision that integrates these interconnected realities.


Furthermore, appropriate regulations are essential to guaranteeing resource protection from various threats. The government, not businesses solely focused on economic growth, should become the primary defender of water quality and the well-being of the population in all regions of the country.


Empowering Community Engagement and Academic Leadership in Safeguarding Costa Rica's Aquifers


The population must be proactive in addressing groundwater contamination. Unlike surface water pollution, groundwater contamination is often invisible until the damage is almost irreversible. However, ongoing awareness is crucial for citizens in all regions. Wherever you find cities, factories, gas stations, mines, intensive farms, large tourist developments, or facilities handling hazardous materials, the water resources are at risk.


Public universities have a critical role to play: supporting communities, providing highly qualified professionals in this field, and conducting research and outreach programs tailored to the knowledge and support needed to address this issue. Regulators and water management authorities need to collaborate with the private sector so that all stakeholders can work together to structure viable solutions for both the environment and the population as a whole. Assessing threats to aquifers and water security is at a crucial crossroads, demanding immediate action.


Discriminant model and hydrogeochemical processes for characterizing preferential flow paths in four interconnected volcanic aquifers in Costa Rica


Preferential flow paths in four interconnected volcanic aquifers in Costa Rica



The deterioration of aquifers in Costa Rica (1)
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