In a classic case of understatement, the environmental minister told a legislative committee Tuesday that the use of polluted water for agriculture can cause health complications.

The minister, Roberto Dobles Mora of  Ambiente y Energía, appeared before the  Comisión Permanente de Asuntos Hacendarios, which is trying to decide if the country should accept a $130 million loan from the government of Japan.

Part of the money will go to build a treatment plant for human waste from the Central Valley.  Dobles spoke of the need to stop this environmental problem.

The situation has been dubbed Costa Rica’s dirty little secret: that a country so dedicated to environmental protection would allow the untreated sewage from its most densely populated area to flow into the sea. The loan from Japan and $100 million in Costa Rican money will make a start at improving the collapsed sewerage system in the Central Valley  and constructing the treatment plant by 2015, it is estimated.

Now much of the sewage runs over ground or through decayed and rotting pipes and eventually ends up in local streams and then the Río Grande de Tárcoles which flows into the Gulf of Nicoya just north of some prime central Pacific beaches.

“The problem is that owing to the pollution, fishing activity is reduced and the people ought to take up other things. It happens exactly the same in the case of tourism,” said Dobles as he addressed the unemployment side of the problem.

Irrigation with polluted water is a way many human diseases and internal parasites are spread.

Mario Quirós, a member of the committee noted that the solution to the problem, the adequate treatment of sewage, has been postponed for decades in the country.

“Here what we have done is pass the sewage from one pipe to another for years,” he said. “We have not given a real integrated solution to the problem of sewage and this has complicated the situation a lot.”

The lawmakers have been treating the matter of the Japanese loan delicately. Although the Japanese have set up a deadline for acceptance, Costa Rica had to seek a new deadline because of the extensive study the project is getting in the legislative committee.

Approval of the low-interest loan equals approval of the project, lawmakers point out. The new deadline is the end of the month.

Ricardo Sancho, executive president of the sewer and water company, has been invited to appear again before the commission. It is his third official visit.