From the Wikipedia page 
Siaya County is one of the counties in the former Nyanza Province in the southwest part of Kenya. It is bordered by Busia County to the north, Kakamega County and Vihiga County's to the northeast and Kisumu County to the southeast. It shares a water border with Homa Bay County which is located south of Siaya County. The total area of the county is approximately 2,496.1 km². The county lies between latitude 0° 26’ to 0° 18’ north and longitude 33° 58’ east and 34° 33’ west. Siaya has been split up into six new districts. Under the new constitution, the role of districts are still unclear as much of administrative authority is being transferred to the county. The capital is Siaya, even though the largest town is Bondo.