The natural timing of freshwater delivery to an estuary may be altered by upstream modifications created by humans. Dams that are created to control flooding can result in reduced seasonal variation of freshwater inflows (Montagna et al. 2013). Urbanization and construction projects change runoff patterns as previously discussed. This can increase the volume of freshwater inflows but shorten the delivery time to estuaries.
![](/sites/default/files/inline-images/Rayburn%20Dam1.jpg)