What steps should be taken to prevent future flooding?

(The following Letter to the Editor has been received from Jim Maloney, a former Decorah resident who now works as a Civil Engineer in La Crosse):

An area in Decorah that has experienced significant flood damage is in the reach of Dry Run Channel as it approaches its outlet to the Upper Iowa River next to Wold Park.   When major regional rainfall events occur with high river stages, all flood gates in Decorah on the river side of the dike are closed  (including near Aase Haugen and the High School pond).  Local stormwater runoff then has no outlet to the river and flooding of the low lying areas occurs.

Emergency responders have done a terrific job using the fleet of portable pumps for the recent flood events to send stormwater over the dike at key locations throughout town.   It appears that flood volume conditions at the Dry Run outlet exceed the capabilities of the portable pump approach.  The City could perhaps consider a permanent high capacity lift station at the Dry Run outlet for instantaneous emergency pumping of stormwater over the dike when the gates are closed.  The City likely  has already discussed this flood protection concept as part of the overall dike system.

The watershed for Dry Run is large with many connected paved areas contributing to runoff.  It extends through town all the way past Centrum Mall to just south of the Hwy 9 Trail bridge.  Dry Run delivers the most local stormwater runoff volume towards the river in a relatively short amount of time.
 
A permanent pump lift station designed to handle the Dry Run peak flows would provide a higher level of flood protection for the residences and businesses along the South Avenue area.  This type of facility is not cheap, but could perhaps be funded in part by the stormwater utility being considered by the City.

Porous pavements, infiltration/detention basins and increased green spaces improve stormwater runoff quantity and quality.  Decorah has wisely adopted a stormwater management plan to move forward with these types of improvements.