Levee Crest Decision with Conflicting Forecasts
You are the director of a 240,000-resident county emergency management agency. The National Weather Service has issued a flood watch for the Cedar River; two levee reaches are rated 'moderate' risk. At 0400 the river gauge forecasts a crest of 31.2 ft by 1800-1.2 ft above the levee design crest-but the forecast cone spans 28.5 to 34.0 ft. A 120-bed hospital, two nursing homes with 96 residents, and a 900-unit mobile home park lie inside the inundation zone for a 33-ft crest. You have 14 hours of usable daylight, four contracted school buses, and a mutual-aid agreement with a neighboring county that is also activating. The hospital CEO says evacuation would cost $400,000 and disrupt 60 scheduled surgeries. Your EOC is at Level 3 with six staff. The county administrator asks you to 'wait for the 1000 briefing.'
1. What decision trigger and timeline will you use before the 1000 briefing? Identify the indicators that would move you from monitoring to phased evacuation.
Read the worked answer
Separate the information update from the decision. Waiting until 1000 is acceptable only if no trigger has already been met. Work backward from evacuation timelines: moving 96 nursing home residents takes roughly 6–8 hours with ambulances and buses; moving a 120-bed hospital takes 8–12 hours, especially with 60 surgical cases. With 14 hours of daylight, the latest defensible start for care facilities is about 1200; for the hospital, about 1000–1100.
Set explicit triggers:
- NWS flood warning or a 0600 forecast crest at or above 31.5 ft: evacuate the two nursing homes and the mobile home park.
- Crest at or above 32.5 ft, or any observed levee distress: begin hospital evacuation.
- Forecast shift below 29 ft: continue monitoring with pre-positioned resources and pre-scripted messages.
Because the upper cone reaches 34 ft and the forecast already exceeds the design crest, 'wait' assumes risk you cannot recover from if the levee fails early. Use a worst-credible-case planning assumption for life safety, but tell the public what is known, what is uncertain, and when the next update comes. Elevate the EOC to Level 2, request the mutual-aid liaison now, and document the administrator's direction and your advice.
2. How do you sequence evacuation of the hospital, nursing homes, and mobile home park, and how do you handle the CEO's cost objection?
Read the worked answer
Life safety outranks cost and continuity, but evacuation itself carries risk, so sequence by time-to-move and exposure. Nursing homes first: 96 residents, lower acuity, 6–8 hours, and receiving facilities must be confirmed. Start the mobile home park at first light at the same time: it has the highest life-loss potential in a 33-ft inundation scenario. Use WEA, route notification, and door-to-door with sheriff's deputies; stage the four buses for repeated trips. Hospital: begin pre-evacuation actions now-protect records, stage ambulances, identify receiving beds, notify surgery of likely cancellations-and move ICU, ventilator, and dialysis patients when the trigger is met. Do not order a full hospital evacuation on a single 0400 forecast without confirming floor elevation and access; if the hospital's occupied floors are below the 33-ft inundation level, full evacuation is indicated.
The CEO's $400,000 and 60 surgeries are real consequences, not decision criteria under imminent life threat. Acknowledge them, ask the CEO to document the objection, and offer a partial-evacuation option that preserves capacity if the crest trends down. Do not let the cost estimate become the reason to delay; document the risk tradeoff and who made the call.
3. What public message do you issue at 0600, and how do you address forecast uncertainty without causing either panic or complacency?
Read the worked answer
Use a plain-language, action-oriented message with a time stamp and a next-update time. State: the river is forecast to crest at 31.2 ft, above the levee design level, with a plausible range of 28.5–34 ft; people in the mobile home park and low-lying areas should leave now, not wait; nursing home residents are being moved; the hospital is preparing. Avoid false precision and avoid 'the levee will fail.' Say 'the levee may be overtopped or fail; we are acting on the worst credible case.'
Channel: IPAWS/WEA, reverse 911, social media, local radio, and door-to-door in the mobile home park. Give a destination and a route, not just a warning. Counter complacency by naming the consequence of staying-rising water can cut access before the crest. Counter panic by giving a schedule and a shelter location. Update at 0900 and 1200 even if nothing changes; silence breeds rumor. Keep the hospital CEO's cost objection out of public messaging; coordinate with the hospital's public information officer so clinical restrictions are explained by the hospital, not by the county.