Water Distribution Systems
As the water is drawn from the source into the distribution system, free swimming mussel larvae can be drawn in during the reproductive season and small juveniles can be drawn in all year around. Carbon steel, stainless steel, PVC and concrete piping are all at risk of settlement. Copper piping or alloys with high copper content are at much lower risk of fouling but can still become fouled if a bio-film builds up on the copper material.
Most irrigation system distribution piping is composed of relatively small diameter piping where the water flow is chronically less than 4.5 ft/s. Under such conditions, larvae may settle and start to grow, reducing laminar flow at the pipe surface. This creates ideal conditions for further settlement. The subsequent development of dense colonies in turn decreases the amount of water available to the system. If the distribution system is on the surface and flows very slowly, the water temperature within the piping may increase sufficiently to prevent settlement. Temperatures over 83ºF may eliminate Eurasian mussel veligers. Embedded, small diameter piping is of particular concern because in most cases the piping is not easily accessible for cleaning.