Fish-farm water could pose long-term threat to Nile Delta groundwater: Researchers

Using water from the Bahr El-Baqar Drain in fish farms in the northeastern Nile Delta could pose a long-term threat to groundwater and irrigation canals, even if pollution is not currently detectable in groundwater samples, a new study warns.

Published in Water Science, the study examined an area of about 349 square kilometres, where fish farms occupy nearly one-quarter of the land. Researchers collected 12 groundwater samples, along with samples of water used in aquaculture, in 2025. The groundwater samples showed no detectable heavy metal contamination, but the aquaculture water contained elevated levels of cadmium, cobalt, lead, chromium and nickel.

Mohammed Hagage, a researcher in the Engineering Applications and Water Division at Egypt’s National Authority for Remote Sensing and Space Sciences and the study’s lead author, said the main concern is not necessarily what appears in a single sample, but what could gradually accumulate over years.

To assess that risk, the research team used a computer model to simulate how pollutants could move through the subsurface over a 50-year period.

The simulation showed that contamination plumes would generally move southeast, following the direction of groundwater flow. Cadmium emerged as the most concerning metal in terms of spread and accumulation, with its stored mass in the aquifer projected to reach about 291,000 kilograms by the end of the simulation period.

The irrigation canal network acted as a hydrological trap, limiting the wider spread of contamination while also receiving part of the polluted groundwater, creating a gradual risk to irrigation-water quality.

The study recommends that Bahr El-Baqar water should not be used for aquaculture without treatment. It also calls for stricter water-quality standards and continuous monitoring of groundwater and irrigation canals.

However, the study has several important limitations. There were insufficient historical heavy metal data to calibrate the transport model, while some geochemical values were taken from previous studies rather than site-specific experiments. The model also assumed stable groundwater conditions.

As a result, the researchers’ findings should be interpreted as possible long-term scenarios rather than exact predictions.

The paper does not identify a specific funding body, and the authors declared no competing interests.

The post Fish-farm water could pose long-term threat to Nile Delta groundwater: Researchers first appeared on Dailynewsegypt.