A hedonic model is used to measure the change in value of residential lots in Rockport, Texas, resulting from Section 404 of the U.S. Clean Water Act. Results show that average lot values initially decreased, went though a six-year adjustment period, and then stabilized on a higher price path resulting in a positive net effect on average lot values throughout the Rockport area (with the exception of a particular subdivision). The results indicate that Section 404 generated both regulatory "takings" and "givings," suggesting that both effects should be considered when assessing the benefits and costs of regulatory events and compensation claims.