Willemsen (D) purchased undeveloped land and improved the land with landfill such that it was no higher in elevation than the adjoining Crest (P) lot and this, in turn, reversed the natural water flow across D's land to P's land. While making improvements, D installed a $68,348.94 sewer drain and offered P the opportunity to hook up and make a connection at $9,000. P refused, and when the improvements were finished, P's land became flooded. P claims that it sustained $4,500 in damages and that a connection to the sewer system would cost it another $11,620 for a total of $16,120 in damages. D denied liability for the accumulation of standing water caused by the development of its own property. P sued D, and the trial court denied P's request for compensatory damages and cited the monies D had expended for the storm sewer connection and ruled that D was merely developing its property for business purposes and that D had no duty to maintain its lot in the form of a neighborhood pond or catch basin. The court found that the diversion of the surface water onto P's property was neither intentional nor unreasonable conduct. The court of appeals reversed this ruling and held that D had diverted the normal flow of water and as such its conduct was unreasonable. D appealed.