First off I must do a bit of bragging. AroundDesMoines.com posted a link to the FEMA floodplain map as found on the Polk County Auditor’s website on Wednesday. That map shows the 100-year and the 500-year floodplains separately. On Friday, when the city decided to tell residents in the 500-year floodplain it was recommended they evacuate, the city, the county, and numerous television and other media organizations were rushing around trying to get graphics of only the full 500-year floodplain out to people. Moreover, the link from the auditor’s website shows the floodplain for all of Polk County. The map the city was circulating on Friday showed only Des Moines itself.
I must also apologize. The floodplain map incorporates the GIS street-by-street background that governmental and technical people favor. That means it can take a long time, even with high-speed connections, to download the complete pdf of the map. Usually I try to create a less graphic-heavy version of such reference items but I just did not have the time to download the map properly myself to see where the floodplains lie. This is not the first time that I have found a government’s desire for detailed information to be a hindrance in providing vital information to the public.
The differences between the 100-year and the 500-year floodplains can be minor or major. In Ankeny, the 500-year version covers considerably more area than the 100-year, but that’s from Fourmile Creek, if I remember the map correctly. That is an observation that residents should pay attention to as they consider additional conversion of agricultural land into housing developments.
Along the Raccoon River, there are minor variations between the two floodplains. There is slightly more variation along some of the creeks running through Des Moines. The biggest change can be seen around the bends in the Des Moines River. This includes the area where the Birdland Marina is located, the area just south of the marina, and the main downtown area, including the east, west, and south sides of downtown. This is not surprising for those people who understand how rivers have changed their channels through flooding over the millennia.
Over 1,000 people found their way to this little ol’ site in the past few days and discovered that some people still believe journalists can do their own research. As I tried to follow the joint press conferences held by governmental agencies over the past few days, I was struck by how they started out being informative then sort of faded into repetition. That is exactly how I felt about much of the news coverage, too. That’s part of what made Friday morning’s panic so laughable by Friday afternoon.
Officials and the news media were all abuzz about a voluntary evacuation of downtown Des Moines. Turns out somebody noticed an erroneous gauge reading on Beaver Creek in Grimes that suggested an additional one or two feet of water was heading downstream to the Des Moines River. The morning news coverage that I caught neglected to mention the reason for the evacuation. These were the same people who kept telling the public that rumors about Water Works being flooded were just rumors. The outcome is even funnier. Supposedly because of the threat of more water, the Army Corps of Engineers reduced the water flowing out of Saylorville Lake which meant the crest of the Des Moines River was much lower than projected. Then officials told residents and businesses to keep evacuating just to make sure there wasn’t danger due to levee breaks.
M.R. Field covers local events for AroundDesMoines.com. 
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