Cedar Rapids, Iowa — the state’s second-largest city at about 137,000 residents — has been shaped by the Cedar River in ways both beautiful and devastating. The 2008 flood, which inundated 10 square miles of the city and caused $5.4 billion in damage, was the worst natural disaster in Iowa’s history. It also destroyed much of the city’s water infrastructure.
But the flood was the dramatic event. The chronic threat is quieter and comes from Iowa’s agricultural landscape.
The 2008 Flood: When the Water System Drowned
In June 2008, the Cedar River crested at 31.12 feet — more than 19 feet above flood stage. The city’s water treatment plant was overwhelmed:
- The Northwest Water Treatment Plant was flooded and knocked offline
- The city’s main water supply was disrupted for days, affecting all 137,000 residents and regional industry
- Emergency water distribution became a citywide operation
- Contamination — Floodwater mixed with sewage, industrial chemicals, household hazardous waste, and agricultural runoff flowed through streets and into the water system
Cedar Rapids rebuilt, investing over $750 million in flood protection including a permanent flood wall system. The 2016 flood tested these new defenses — the river crested at 22 feet, again above flood stage, but the new protections held better than 2008.
Nitrate: Iowa’s Perpetual Water Quality Battle
Iowa may be the epicenter of America’s agricultural water contamination crisis, and Cedar Rapids is on the front line.
The state’s intensive corn and soybean agriculture depends on nitrogen fertilizer, and the excess runs off into every waterway in the state. The Cedar River, which supplies Cedar Rapids’ drinking water, carries some of the highest nitrate loads in the Midwest.
The challenges:
- Nitrate levels in the Cedar River regularly approach or exceed the EPA MCL of 10 mg/L during spring and early summer, when snow melt and spring rains flush fertilizer from fields
- Cedar Rapids’ water plant must actively manage nitrate through blending, treatment adjustments, and sometimes switching source water
- Des Moines Water Works’ 2015 lawsuit — Cedar Rapids’ neighbor 100 miles west sued upstream drainage districts over nitrate contamination, highlighting the scale of Iowa’s agricultural runoff problem
- Climate change is intensifying the problem — More intense rainfall events flush more nitrogen from fields in shorter periods, creating higher peak concentrations
Cedar Rapids uses a combination of treatment approaches to manage nitrate, including ion exchange treatment at its newer water treatment facility. But the underlying source — millions of acres of fertilized farmland upstream — isn’t going away.
Atrazine and Other Agricultural Chemicals
Nitrate isn’t the only agricultural contaminant in the Cedar River:
- Atrazine — One of the most commonly used herbicides in corn production, regularly detected in Iowa surface waters. Cedar Rapids’ treatment removes it, but detections in source water are consistent.
- Other pesticides and herbicides — Multiple agricultural chemicals are detected in the Cedar River at various times of year
- Phosphorus — While not directly a drinking water health concern, phosphorus runoff contributes to algal blooms in Iowa’s rivers and reservoirs
The Environmental Working Group has consistently ranked Iowa among the worst states for agricultural contamination of drinking water sources.
Infrastructure Investment Post-Flood
The silver lining of the 2008 disaster: Cedar Rapids was forced to modernize its water infrastructure. The rebuilt system includes:
- New treatment technology including ion exchange for nitrate removal
- Flood-resistant design with critical components elevated above projected flood levels
- Redundancy — multiple source options and treatment paths
- Advanced monitoring for real-time water quality tracking
The city’s water utility, Cedar Rapids Water, now operates one of the more modern treatment systems in Iowa.
What the Data Shows
From Cedar Rapids Water’s most recent CCR:
- All regulated contaminants within EPA limits
- Nitrate levels managed below the MCL (10 mg/L) but with seasonal peaks requiring active treatment
- Atrazine detected but within EPA limits
- Disinfection byproducts within limits
- Lead at 90th percentile below action level
- No SDWA violations
What Cedar Rapids Residents Should Do
- Trust the treatment — Cedar Rapids’ rebuilt water system is modern and well-operated. The nitrate challenge is managed, not ignored.
- Spring caution — If you’re pregnant, have infants, or have health concerns, be aware that nitrate levels peak in spring and early summer. The utility manages this, but extra awareness during this period is reasonable.
- Private well owners — If you’re on a private well in Linn County’s agricultural areas, test for nitrate at least annually, and more often in spring. Iowa’s private wells frequently exceed the nitrate MCL.
- Flood preparedness — Cedar Rapids’ flood protection has improved dramatically, but keep emergency water supplies. The 2008 and 2016 floods showed that river cities must be prepared.
- Support upstream conservation — Cedar Rapids’ water quality is determined by land use practices hundreds of miles upstream. Conservation practices (cover crops, buffer strips, wetlands) in the Cedar River watershed directly improve your drinking water.
Cedar Rapids has turned disaster into investment — the city’s water system is better now than before the flood. But the underlying agricultural contamination challenge isn’t something one city can solve. It requires watershed-scale change across Iowa’s farming landscape.
If you’re concerned about your water quality, a certified water treatment professional can test your water and advise on solutions for your specific situation.