The Santa Clara and Virgin Rivers run through the communities of Gunlock, Santa Clara, and St. George, Utah. Fertile lands and access to water has historically linked agricultural lands to the river. The large trees, cooler temperatures, and aesthetic features make properties near the river more valuable. But, as was evident in January 2005, there are risks associated to living adjacent to a river.
Rivers flood. Common floods inundate areas closest to the central channel; higher, less frequent floods affect higher areas. First hand testimony of many who witnessed the flooding along the Santa Clara suggest that the extreme bank erosion was commonly initiated as tree trunks and other floating debris blocked the narrow main channel redirecting the force of the flow against unprotected banks. Once outside the vegetated riparian area, the redirected flows spread across pasture or other surfaces often eroding a new main channel.
The banks of the Santa Clara and Virgin Rivers have very little inherent strength. Channel stability in the past has largely depended upon thick stands of vegetation surrounding and containing the channel/floodplain. This vegetation strengthened banks and tended to keep the strongest stream flow in the central channel flowline. However, in many instances during the January 2005 flood, uprooted vegetation blocked the central channel and diverted flows against unprotected banks.
Floods like the one in 2005 are likely to occur again on both Santa Clara and Virgin Rivers. The following documents are presented to guide in the emergency repair work now underway, create a plan for dealing with future flooding, and inform those who live, and own property along the banks about the considerations and potential dangers associated with living near a waterway of this kind.