What happened? 

On Friday evening, 21 June 2024, a torrential rainfall overwhelmed the Iowa Great Lakes (IGL) area.  An already saturated land mass could not handle the 5-10” rainfall that evening, and residents of Jones Beach awoke to threatening waters from a rising West Okoboji, as well as 30” of flood waters over the majority of Okoboji Boulevard.  Over 95% of the 30 homes along Jones Beach were damaged by flood waters or backed up sewer systems.  

What is at stake? 

Over 30 homes remain extremely vulnerable to another flood event if steps are not taken to address immediate short term flood resiliency as well as long term changes to the watershed of Garlock Slough and the Iowa Great Lakes ecosystem. 

What needs to be done? 

Jones Beach residents, family, friends, and concerned citizens request the following 4 actions to be taken:   

1.        Creation of a Short Term (spring 2025 and beyond) flood resiliency plan for Garlock Slough

a.        We believe we need to keep Garlock Slough sufficiently “dry” to serve as a “shock absorber” against future weather events similar or worse to what was experienced the night of 21 June.  To the untrained resident, until further studied, we believe this should be at least 3 feet, or 75,000,000 gallons, below the Ordinary High Water Level for Garlock Slough.  

b.        This would also include monitoring and maintaining the pumping operation and retention pond currently in place immediately west of the slough.

c.        This would also include a policy or protocol for how best to monitor and maintain the fish gate at the inlet, up to and potentially including erecting a sand bag barrier to the inlet and installing pumps at that location as well to augment evacuation of the slough.

Specific Request:  Can the DNR monitor and maintain Garlock Slough and the associated retention ponds to a low enough level to fully prevent Garlock from going over its OHWL ?

 

2.        Creation of a Long-Term (2026 and beyond) flood resiliency plan for the Garlock Slough Watershed

a.        This would start with a feasibility study of the entire watershed that would outline actions to be taken that would provide a more robust protection from future flood events.

b.        This would include public and private actions to increase capacity of retention ponds, creating new retention ponds, berms or barriers to be constructed at strategic points in the watershed, exploring a spillway as an additional outlet to West at the fish gate, and appropriate amendments to Garlock Slough such as dredging to increase capacity to prevent the flooding experienced in 2024.

c.        Questions that would need to be addressed are:

                                                                                             i.         How much rain and how much runoff in the slough watershed would have been enough to fill the slough to overflowing?

                                                                                          ii.         What is the capacity of the slough and at what surface elevations?

                                                                                       iii.         Where are the storage and settlement ponds and what is their capacity?

                                                                                       iv.         How much of the excess water in the slough could have been held at the higher elevations?

                                                                                          v.         What storage or settlement ponds could be constructed to increase the capacity in the higher elevations?

                                                                                       vi.         What can be done at the slough outlet to increase velocity and volume of flow from Garlock to West?

Specific Request: We need the City of West Okoboji, FEMA, DU, or other local foundation to fund a feasibility study of the Garlock Watershed to identify actions to take to prevent future flooding?

 

3.        Support for the overall IGL Watershed changes

a.        We believed that a variable weir water control capability needs to be installed at the 230th Street bridge location at lower gar in order to manage the “trough to peak” water conditions during various low and high-water years on the IGL chain of lakes. This variable weir capability would be needed to modulate the release of water so as to protect downstream communities from flooding.  The reason Jones Beach needs this flow to increase under the bridge is to better enable the IGL leaders to proactively draw down water levels over time in response to the forecast of a high rainfall event, thus alleviating the need to evacuate water in short periods of time, causing flood damage, shoreline collapses, etc.

Specific Request:  To the Dickinson and Clay County board of supervisors responsible for flood resiliency, please register the Jones Beach homeowners (~ 30 homes) as in support of this bridge being built.

 

4.        Municipal Planning Coordination and Alignment

a.        As plans for updating the sanitation sewer and the water main line are delt with by the City of West Okoboji and the Iowa Great Lakes Sanitation Sewer District, we would like to see coordination of flood water resiliency projects to be included in these projects.  For example, when the water main line is replaced (and potentially the sewer line at the same time), we would like to see berms to be built along Garlock to future restrain water from encroaching on homes.

b.        There may be other recommendations resulting from 2a above (feasibility study).  Our ask is that these efforts be coordinated and promptly implemented in a way that utilizes tax dollars efficiently and effectively, and limiting further financial distress to residents who are already facing substantial personal loss on their homes.