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In 1992 and 2002, investigations on the water quality and hydrology were carried out in a small agricultural catchment where swine waste was stored in earthen waste storage. The in-stream nitrogen loads and the nitrogen inputs on a sub-catchment scale were estimated and compared between 1992 and 2002. For the entire catchment, the estimated nitrogen inputs increased from 22.5 to 32.9 ton year -1 (from 406 to 594 kg ha -1 year -1 ), whereas the nitrate nitrogen concentration at the outlet was constant-27 mg l -1 . In a sub-catchment (area C) with earthen waste storages, the nitrate nitrogen concentrations at the outlet were high, 42-51 mg l -1 . In a sub-catchment (area A) with an earthen waste storage, which was not in service since 1990, although the nitrogen inputs were maintained at 390 kg year -1 (53 kg ha -1 year -1 ), the nitrate nitrogen concentrations at the outlet decreased from 26 to 4.9 mg l -1 . With assuming that the nitrogen transport rates for sources except swine waste are equal to the rates estimated for a sub-catchment without earthen waste storage, the in-stream nitrogen loads for area A were estimated to decrease from 1,334 to 94 kg year -1 and the transport rates for area A were estimated to decrease from 3.95 to 0.73. These results suggest that the effluent from earthen waste storage has affected surface water quality two years after the storage was out of service and its effect largely decreased after a decade.

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