The researchers studied how well certain ponds in Jordan clean wastewater for a year. They found that the ponds removed pollutants at different rates, even at the same temperature. The ponds generally cleaned the water slower than expected, with the fastest rate being 0.16 per day. When one pond was emptied after 18 months, they found sediment spread out with an average depth of about 4 cm. They also made a simple model to predict how much sediment builds up over time in the ponds.