For some, levee eval. spells bad news


(11/7/2018)

by CHRIS ROGERS

If it weren’t for Winona’s levee system, most of the core city would be underwater in a major flood. On Monday, the Winona City Council got some bad news about the levee system. Because of deficiencies with the system, some Winona properties may enter the floodplain when the Federal Emergency Management Agency (FEMA) updates its floodplain maps. That means homeowners may be required to purchase expensive flood insurance. Additionally, Winona City Council member Michelle Alexander reported that some insurance companies are already warning local businesses that their insurance premiums may increase because the city’s efforts to re-certify its levee system — which began in 2015 — are still dragging out.

“I have no fears of actual flooding, but I do get concerned about the flood insurance requirements,” Winona Public Works Director Keith Nelson said. According to Nelson, Winona’s levees are in good condition and not in danger of failing. The issue is whether they meet FEMA’s requirements for drawing floodplain maps. “I think [properties added to the floodplain] would be unlikely to ever flood,” Alexander stated. “That’s what’s frustrating about this … This is about FEMA not liking the system that was built.” Nevertheless, having a property added to the floodplain map has real-world consequences. “Those homes will have problems selling, the banks will have trouble financing … and some people will have to budget for flood insurance. It’s expensive,” Alexander said.

Since levees broke in New Orleans during Hurricane Katrina, flooding the city and contributing to the storm’s 1,833 deaths, the U.S. Army Corps of Engineers (USACE) has been reevaluating levees across the country. At the same time, FEMA is redrawing floodplain maps across Minnesota and other states, including new hydrologic models that account for heavier rainfalls and bigger floods in recent decades. If Winona’s levees are USACE-certified, FEMA will count properties on the “dry side” of the levees as being outside the floodplain. If the corps does not endorse the levees, FEMA’s floodplain maps could change, putting properties into the floodplain for the first time. Under federal law, most mortgages require homeowners to buy flood insurance for homes within the floodplain. Flood insurance can cost thousands of dollars per year.

Preliminary studies suggest that, because of problems with the Gilmore Creek levee system and the city’s internal drainage system, the floodplain may expand to include some Winona properties for the first time, Nelson reported this week. He stated that some low-lying properties near the county ditch number three — which funnels water from Bollers Lake to Lake Winona along Kramer Drive and underneath Cotter Schools’ athletic fields — could be added to the floodplain, as well as some low-lying properties near flood system pumping stations — such as at the foot of Washington Street and the foot of High Forest Street. Nelson stressed that, at this point, it is unclear how much the floodplain maps will actually change or whether any properties will be added, but that those areas are have the greatest potential of being added to the floodplain.

Will properties near ditch, Lake Winona, pumping stations join floodplain?

In addition to the levees that hold back the Mighty Mississippi, Winona has some levees protecting parts of the city from flooding on Gilmore Creek. Gilmore Creek flows through Gilmore Valley, past Saint Mary’s University (SMU), into Bollers Lake, through county ditch number three, into Lake Winona, through county ditch number four, and spills out into the Mississippi River at an outlet on the far East End of Winona. Just downstream of SMU and surrounding Bollers Lake, there are levees that protect the Ronald Avenue neighborhood and the area around Shopko.

The primary problem with the Gilmore Creek levee system is that a portion of the dike was designed by the USACE to be overtopped during a 100-year flood, Nelson stated. Actually, it is a weir, not a dike, Nelson said, but in any case, during major flooding, water flows over the top of the structure and pours into county ditch number three and flows toward Lake Winona. That is how the USACE originally designed it to operate, but that is not good enough for FEMA, which insists that every foot of the dike be tall enough to hold back a 100-year flood and then some, Nelson explained. Because the Gilmore Creek levee system sends floodwaters spilling down county ditch number three, low-lying properties near that ditch and near Lake Winona are at risk of being added to the floodplain. Those properties have always been subjected to overflow from Bollers Lake; what is changing is that FEMA’s maps may soon reflect that risk. The city, the USACE, and FEMA are just beginning a process to figure out which properties would be affected, Nelson reported. “I don’t know the answer to that yet,” he stated.


Then there are the properties near flood system pumping stations. At various points along the Mississippi River levee system — Riverview Drive, Washington Street, Kansas Street, High Forest Street — there are pumping stations that pump water out of the city and into the river. Their purpose is to keep the dry side of the levee dry. However, Nelson reported that, according to a recent study by Stantec engineering consultants the city hired, the pumping stations cannot move enough water to keep the city dry during a 100-year flood event on the Gilmore Creek watershed. If Winona got a major flood and rain event in Gilmore Valley at the same time that the Mississippi River was high — not necessarily a major flood, but high enough to require some drains to be closed — the city’s pumps could not pump fast enough to keep the city dry, and the city would experience internal flooding, with water ponding around some of the pump stations, particularly Washington Street and High Forest Street, Nelson said.

The preliminary analyses by Stantec shows that some properties around the Washington Street and High Forest Street pumping stations would enter the floodplain, but it is just preliminary, Nelson reported. Stantec recently delivered maps of those areas to the city, but Nelson declined to release them. “I don’t want that out there yet,” he said.

Winona aims to clean up existing system; no plans for big, new fixes

Winona and the USACE are working toward a solution that will keep most of Winona out of FEMA’s floodplain. When the first laid plans in 2015, Winona’s levee system was supposed be re-certified in 2017. Nelson said that the city had a hard time inspecting culverts underneath the levee and that a consulting firm it originally hired to complete the recertification process did not produce the kind of in-depth analysis the USACE wanted, but he stated that the main reason for the delay had to do with a portion of USACE-owned levee on Prairie Island.

The USACE built all of Winona’s levees, but the city now owns and is responsible for maintaining most of them. There is one exception: a stretch of Mississippi River levee that runs from the Prairie Island spillway upriver toward Minnesota City. That section is owned by the USACE, and Nelson reported that the USACE found that an unacceptable amount of water was flowing through the levee. Rather than take on a massive construction project to fix it, Nelson said that the USACE opted for an alternative to the normal re-certification process, a study called a high-risk analysis. The analysis would consider the risk of flooding in Winona, and, if the results are favorable, it would have the same effect as re-certification: FEMA floodplain maps would “count” the levees and most of Winona would stay out of the floodplain.

Nelson stated that the USACE’s decision to pursue a high-risk analysis for its portion of the levee system required the city to do the same. “Because it’s essentially the same levee, the same system, you have to do the same process on the whole system,” he told the Post. He said that the USACE should begin the study in early 2019, but that he did not know how long it would take. City officials expect that the city will have to pay for half of the study and estimate the city’s share to be $300,000.

In addition to paying for a very expensive study, Winona also needs to catch up on maintenance items that have been on its to-do list since before 2015, including finishing inspections of levee system culverts and pipes, making any necessary repairs, and removing “encroachments” on the levee.

Encroachments include anything near the levee that was not built by or approved by the USACE, whether they be picnic tables or conveyor belts. Encroachments that affect the structure of the levee itself are especially important, Nelson stated. “Power poles or flag poles pushed into the levee, or a fire pit dug into the levee, or trees [growing] into the levee itself — all of those things have the potential to break the levee,” he said. At Prairie Island, there are a number of residential properties that have erected encroachments on the levee — such as steps leading down to the river — and east of downtown, many industrial businesses have placed other encroachments, such as fencing or conveyor belts used for loading barges. The city itself will have to prove to the corps that none of the alterations it made to the city-owned docks on Riverview Drive compromised the levee structure, and Nelson reported that the city will be sending out letters to property owners this month warning them to remove the encroachments or else. At Monday’s City Council meeting, Winona City Attorney Chris Hood said that the encroachments could be considered nuisances that the city could order property owners to remove, and, if property owners refuse, the city could go as far as charging the owners with a criminal misdemeanor.

The city is not currently planning major fixes to correct the issues with the internal drainage system or with the Gilmore Creek levee system that threaten to put some property owners into the floodplain.

The only way to correct the problem with Gilmore Creek’s levees would be to build dikes around the ditch and all of Lake Winona, Nelson explained. “It’d be another massive, massive project,” he stated in an interview. “I don’t know if there’s room for that or if you would have to take out homes,” he added. “We have not researched that.” At the council meeting, Nelson was categorical about the Gilmore Creek levee system: “We are not going to get accredited.”

Could the city fix its pumping problems? “I don’t know the answer to that yet,” Nelson responded, adding, “I don’t know if there is [one].” He said that the city would have to work with the USACE to see if it would be possible to replace or upgrade the pumping stations. “I’ll be looking into that,” Nelson added.

Alexander was not optimistic about the chances of on-the-ground fixes to the Gilmore Creek and internal drainage problems being cost-effective. “I always like things to have a discussion, but I think the expenses will be astronomical,” she stated. The city should make sure property owners in those areas have plenty of warning so they can prepare for the potential floodplain map changes, Alexander said.

It is unclear when FEMA will propose updated floodplain maps. Like the city’s efforts to re-certify the levee system, that process has dragged out years longer than expected.

Keep reading the Winona Post for more on this story.

Chris@winonapost.com


Correction: An earlier version of this story misquoted Winona Public Works Director Keith Nelson as saying Winona's levees are not in good condition and not in danger of failing. Nelson said the levees are in good condition. The earlier version also incorrectly identified the reason some properties near Lake Winona may be added to the floodplain. Flooding within the Gilmore Creek watershed — not the city's internal drainage system — is the cause.

 

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