MORE than a month after researchers at theUniversidad Nacional (UNA) released a study citingpotentially dangerous levels of nitrates and volatileorganic compounds in underground water sources thatprovide much of the Central Valley’s drinking water,government water-service officials continue to discreditthe study’s results.“Right now, San José is receiving clean drinkingwater 24 hours a day,” said Rafael Villalta, president ofthe National Water and Sewer Institute (AyA). “At thistime, we are complying 100% with international norms.We’ve made an enormous effort for the past 44 years,and we’re proud that Costa Rica has potable water.”Furthermore, he added, AyA seeks to improve waterquality with a planned multimillion-dollar sewage-treatmentplant for the greater metropolitan area.Villalta says the UNA study incorrectly deems theCentral Valley’s water dangerous to drink because it usesa standard of 10 mg/L as the maximum acceptable limitfor nitrates in drinking water. AyA uses a 50 mg/L standard,the maximum acceptable limit established by thePanamerican Health Organization (OPS), he said.ALAN Benavides, the director of the Heredia PublicServices Company (ESPH), which provides drinking water to residents of the city of Heredia,north of San José, said he doesn’t understandwhy AyA is disputing the results ofthe UNA study, which ESPH contributed¢25 million ($52,854) to help fund.“Instead of criticizing UNA, we shouldtake advantage of the results to encouragethe government to help fund an urgentlyneeded sewer system,” Benavides said.After the results of the study by theHeredia-based public university weremade public in last month (TT, April 15),AyA released a series of statements assertingthat 50 mg/L is the acceptable limit(TT, April 29).“The researcher (Reynolds) uses amaximum allowed limit of 10 mg/L,which is not in agreement with the stateregulation, causing a mistaken interpretationof the results and confusing the population,”AyA stated.UNA countered that statement with afull-page paid ad in the daily La NaciónApril 28 explaining the results of thewater-quality study. The debate has continuedin e-mailed statements to the pressand opinion columns and letters to the editorpublished in La Nación.DR. Jenny Reynolds, head of UNA’sEnvironmental Hydrology Center, said theresults of the 12-year study indicate potentialproblems in underground watersources that supply much of the CentralValley’s drinking water.She said the study’s results are thesame whether read with a 10 mg/L maximumallowable limit for nitrates or a 50mg/L limit because nitrates can beexpressed two ways, either as Nitrate-N(nitrogen) or as nitrates, she added.“Anyone who knows a little aboutchemistry knows that it doesn’t matterwhether you use 10 mg/L or 50 mg/L. It’slike saying 30 centimeters or 15 inches.It’s a way of expressing the same thing,”Reynolds said.According to the Illinois Departmentof Public Health’s Web site, “The U.S.Environmental Protection Agency uses 10mg/L as a mandatory national standard forpublic supplies under the Safe DrinkingWater Act. The 10 mg/L standardexpressed as nitrogen is equivalent to 45mg/L expressed as nitrate.”UNA expresses nitrates as Nitrate-N(nitrogen) in its study and uses a maximumacceptable limit of 10 mg/L.AyA, however, stands firm in its positionthat UNA is using the wrong parametersto evaluate the quality of the water.According to Villalta, the institution was“bothered” and “surprised” by the way inwhich UNA released the study and thenegative publicity it has generated.“They used standards that are not thenorm and generated confusion. It causedus a lot of harm,” he said. “What hurt usthe most is that we had people calling us toask if they had to boil their water.”According to Villalta, AyA is currentlymonitoring underground water sourcesto check nitrate levels in response to thecontroversy.However, it is the responsibility ofeach municipality to work with farmersand the Ministry of Public Health to preventagricultural chemicals from enteringunderground water sources, he said.LOOKING toward the future, Villaltasaid AyA’s most important water-qualityinitiative is a large-scale sewer project forthe greater metropolitan area of San José.The system would provide sewage treatmentto areas currently lacking any type oftreatment facility, which would help preventfecal matter from contaminatingunderground aquifers.Villalta said he has been meeting withpublic health officials during the past fewweeks and hopes a $150 million loan fromthe Japanese Bank of InternationalCooperation will be approved by the end ofthe year. The loan would allow implementationof the project’s first stage to begin.Another sewer project planned forHeredia, managed by ESPH, awaits a loanfrom the Inter-American DevelopmentBank (BID), Villalta added.UNA scientists insist sewer projectsalone will not solve the Central Valley’swater problems.“This (the sewer system) is not ananswer,” said UNA researcher FreddyPacheco. “What AyA should do is detectthe origin of volatile organic compounds(VOCs) in subterranean water. VOCs havenothing to do with septic tanks.”He said the sewer projects fail to takeinto account nitrates from animal and agriculturalwastes.In an e-mail to The Tico Times earlierthis month, he cited a study in Stoughton, inthe U.S. state of Massachusetts, that foundnitrate levels in that city’s water supply at 11mg/L. After that study was released,Stoughton authorities immediately issued arecommendation that residents not give thewater to babies younger than six months.Pacheco and other UNA investigatorssay AyA officials are avoiding responsibility,and should take steps such as creatinga subterranean water-managementplan, zoning off and regulating springsand wells and developing more efficientcrop-fertilization techniques to helpimprove water quality.Nitrates: The Good, the Bad and the UglyNITRATES are commonly found in lowlevels in soil, released from the breakdownof animal and plant waste, and are animportant plant nutrient. They dissolve easilyin water and are readily transported byrain runoff that soaks into the ground andinto aquifers. In rivers and lakes, aquaticplants quickly mop them up, but in undergroundbodies of water, there are no livingorganisms to consume them, and there isno other process of decomposition.The journey from the surface downthrough soil and rock is slow, which meansthat nitrates are slow to accumulate inaquifers, but once there, they do not dispersefor dozens or hundreds of years.The sources of pollution are tracked bythe kind of nitrates detected.Scientists in Costa Rica have determinedthat the two major sources of nitratecontamination in the Central Valley arehuman waste and chemical fertilizers usedon coffee fields.High nitrate levels in drinking wateraffect infants and children more intenselythan adults, sometimes causing a conditionthat impedes the blood from carryingoxygen. The adult body is better equippedto handle the problem, but in very highconcentrations, nitrates in drinking waterare harmful to everyone and have beenshown to cause cancer.Source: The Environmental HydrologyLaboratory of Universidad Nacional (UNA).