Flood Zones in Jefferson County, Missouri

The county's floodplain-development permit and 3-foot freeboard rule

Jefferson County's flood damage prevention ordinance requires a floodplain-development permit for any proposed construction or other development within the mapped flood hazard areas described in the county's code -- and that requirement explicitly extends to placing a manufactured home, not just building a conventional structure. For residential development inside the floodplain, the county's permit conditions require that the first floor, including a basement floor, be certified as elevated at least three feet above the calculated 100-year (base) flood elevation -- a freeboard requirement that goes beyond FEMA's minimum baseline and is meant to build in a margin of safety against future flood events exceeding current modeled predictions. Before buying land anywhere near the Meramec River, the Big River, or their tributaries, pull the FEMA flood map for the specific parcel and confirm with the county's floodplain administrator whether a floodplain-development permit and the freeboard requirement would apply to your building plans.

The flood history: 1993, 2015, and 2017 were not one-off events

The catastrophic Midwest flooding of 1993 hit Jefferson County and the broader Meramec River basin hard, and it became the catalyst for Missouri's modern flood-buyout programs. Arnold, just across the Meramec from parts of Jefferson County and a useful comparison case, saw more than 225 properties damaged in 1993 with an estimated $1.6 million in damage; after the city bought out 322 flood-prone homes with FEMA, state, and local funding, a comparable 2008 flood caused only about $12,000 in damage in that same area -- a concrete before-and-after showing what a completed buyout can accomplish. But the risk didn't end with 1993: a major winter storm from December 23-29, 2015 set record river-level highs across east-central Missouri, and the region flooded again in 2017, in both cases trapping some residents in low-lying developed floodplain areas. Growth into the floodplain since 1993 -- new residential lots, subdivision extensions, and construction fill narrowing effective river channels -- has been specifically cited as a factor that has kept flood damage risk elevated in this stretch of the Meramec basin despite the buyout programs.

The 2026 Spring Glen Drive veto: don't count on a future buyout

The clearest, most current illustration of floodplain risk in Jefferson County specifically is the Spring Glen Drive neighborhood in the House Springs area, where residents faced at least three flooding events in the two years leading up to mid-2026. A push for state buyout funding began in 2025, and with the help of State Senator Mary Elizabeth Coleman, a $2 million line item to fund the buyout made it into the state budget lawmakers approved in May 2026. Governor Mike Kehoe then vetoed that line item on July 1, 2026, as part of nearly $500 million in budget vetoes and withholdings, characterizing the buyout as "a local responsibility with minimal statewide impact" that should be pursued through other funding sources -- his administration said it would work with the federal congressional delegation and agencies like FEMA and the Army Corps of Engineers instead, but as of this review no replacement state funding has been confirmed.

The practical lesson for a land buyer: even a buyout that has cleared the legislature, has a named funding amount, and has documented repetitive flood losses behind it can still be vetoed and left unresolved. If a piece of land you're considering has a real flood history, don't factor a hypothetical future buyout into your decision to buy at a discount -- treat the flood risk itself, and the cost of raising a structure or otherwise flood-proofing it under the county's 3-foot freeboard rule, as the number that matters today.

What this means for a specific purchase

1. Pull the FEMA Flood Map Service Center map for the specific parcel, and cross-check it with the county's own FEMA Flood Maps resource, before assuming a river-adjacent property is or isn't in a mapped flood hazard area.
2. If any part of the building envelope falls inside a mapped floodplain, confirm with Jefferson County's floodplain administration whether a floodplain-development permit is required and what the 3-foot freeboard requirement means for your specific building plans and budget.
3. Ask directly whether a property has flooded before -- repetitive-loss history (like Spring Glen Drive's three events in two years) is exactly the kind of thing a seller may not volunteer, and a documented history changes both insurability and resale value.
4. Do not build a purchase decision around the assumption that a future government buyout will bail out a flood-prone property -- the 2026 Spring Glen Drive veto shows that funding can be approved by the legislature and still fail at the governor's desk.
5. Check flood insurance costs and availability for the specific parcel early -- a mapped Special Flood Hazard Area typically requires flood insurance for a federally backed mortgage, and premiums reflect the same risk history discussed above.