Prior to reclamation, Ogura-ike Pond was 4 km in width (east to west), 3 km in length (north to south), 16 km in circumference (with the surface area being approximately 800 ha) and the average depth was 90 cm.
なお、干拓前の巨椋池は東西4km、南北3km、周囲約16km（水域面積約800ha）であり、平均水深は90cmであった。