Blanchard River History

Studies have shown that prior to settlement, 42 percent of the Blanchard watershed was wetlands. Currently, remaining wetlands make up only 3.2 percent of the region. The average annual rainfall in Ohio is 38 inches, most of which is taken up by plant cover or field crops and transpired into the atmosphere. Without the wetlands, 10 inches drains over the surface into the river, and 2 inches reach groundwater for sustained release to the river's base flow of 100 cubic feet per second (CFS).

The Wisconsin glaciation retreated 10,000 years ago, leaving flat plains in northwestern Ohio. The Blanchard River watershed slopes 2 percent and varies 10 feet in elevation. A few glacial moraines and beach ridges from glacial lakes dot the landscape, but are no higher than 30 feet. Soils that developed over the glacial till were poorly drained, so farmers installed ditches and ceramic pipes that now feed the river. About 366,000 farm acres require artificial drainage, and 105,000 acres yield run-off erosion that silts the Blanchard's tributary creeks.

In 2005, daily surface water withdrawal for human activities was 34.78 million gallons, plus another 9.25 million from groundwater. All streams in the watershed are impaired by "nutrient enrichment" (fertilizer pollution) from 380,000 acres planted in corn (31 percent), soybeans (50 percent), wheat (16 percent) and hay. Most streams are low in oxygen and burdened with ammonia run-off. Half are burdened with fine particulate run-off from clay soils. Nevertheless, erosion has declined almost 30 percent from the peak 2.8 tons per acre per year in 1982.

In 2009, the town of Findlay flood gauge had recorded the river at or above flood stage in 53 of the previous 81 years. The largest flow was 22,000 CFS in 1913. The 15,600 CFS flood of August 2007 put downtown Findlay under 2 feet of water. A narrow 22,600-acre alluvial plain floods every year or every other year. In 2009, community groups in Findlay suggested that the Corps of Engineers construct a square mile flood control reservoir 60 feet deep. They also want new zoning to restrict building in the flood plain.

In 2009, the United States Geologic Survey (USGS) inaugurated a warning system for Findlay. The system cues maps for flood stages of 11 to 18.46 feet, the highest stage of the August 2007 flood. The map will help residents understand flood hazards in real time. It was released in February 2009 and used by city staff for flooding in March. In April, the system went live on the Internet. The maps replace the older soil survey maps, which FEMA recognized as failing to communicate hazards effectively.