Description: Catchbasins are structures that sit below the ground that are designed to collect rain/storm water runoff and direct it into the storm sewer system. From above ground they appear as a large grate while below ground they catch debris and sediment and stop it from entering the sewer system. The catchbasins may contain stagnant water that mosquitoes could use for breeding which is of interest to those working on West Nile Virus initiatives . This data reflects catchbasin locations across York Region captured as a result of the West Nile Virus (WNV) Larviciding Program that aims to curb the mosquito population in response to the spread of WNV. One of the contractual obligations of the larviciding contractor was to capture the x,y co-ordinates of treatment locations (catchbasins). This was done through the use of an ArcPad application on GPS units that capture x,y co-ordinates along with larviciding treatment information. Additional catchbasins are added on an annual basis as consultants find new locations during the completion of their contractual larviciding activities.