Water, irrigation, and power systems have flow instrumentation associated with them. The main flow measurement devices for irrigation systems are generally located at the agricultural turn outs, but smaller flow-meters may be located on other parts of the system to verify adequate irrigation. Any instrument using raw water is prone to fouling by mussels, which could affect the readings obtained by the instrument. In lines which have no flow, such as pressure sensing lines, the settlement is likely to occur near the tap end of the line where oxygen and nutrients are available. Water sampling stations which have a regular and low flow of water through them are at particular risk of fouling.