A raceway, also known as a flow-through system, is an artificial channel on land. The water flows from a higher located point to a lower point and flows then back into the river or sea. There are organic raceways and raceways with and without water treatments. Raceways without water treatment discharge wastewater into the natural environment which can have a negative impact. Fecal matter can enter the river and there is a higher chance to spread disease and fish can escape more easily. Water treatment can reduce the impact on the natural environment. In raceways there is better control of negative effects compared to net pens. Disadvantages are the high use of water, discharge of wastewater in surfacewater and the chance of spreading diseases.