Figure 1: StormSensor data showing the Mississippi River backing up into a municipal stormwater system.

Initial Findings

A few months into the study, sudden reverse flows and rapid increases in water levels were detected across all four monitoring points. An investigation determined that the flows were from the Mississippi River. Outfalls to the river in this region have gates to keep the river from back flowing into the stormwater system. 

However, the gates are sometimes left open to allow the stormwater system to serve as additional storage capacity when river levels get high. Prior to monitoring, the city was aware that water from the river would enter the stormwater system.

Initial Findings

A few months into the study, sudden reverse flows and rapid increases in water levels were detected across all four monitoring points. An investigation determined that the flows were from the Mississippi River. Outfalls to the river in this region have gates to keep the river from back flowing into the stormwater system. 

However, the gates are sometimes left open to allow the stormwater system to serve as additional storage capacity when river levels get high. Prior to monitoring, the city was aware that water from the river would enter the stormwater system.

Figure 1: StormSensor data showing the Mississippi River backing up into a municipal stormwater system.

Figure 2: Mississippi River stage during the period StormSensor detected backup into the municipal stormwater system (shown in Figure 1).

StormSensor Detections

The new findings from this investigation were how far into the stormwater system that the Mississippi River was actually infiltrating during high stages and how much capacity the river took up in the stormwater system. StormSensor determined that the river infiltrated at least one mile inland during river stages at NOAA action levels. 

This was an important finding because, when the stormwater system is filled with river water, it does not have the capacity to handle the water it was built to manage – stormwater. Careful management of this delicate system is required to avoid flooding.

Figure 2: Mississippi River stage during the period StormSensor detected backup into the municipal stormwater system (shown in Figure 1).

StormSensor Detections

The new findings from this investigation were how far into the stormwater system that the Mississippi River was actually infiltrating during high stages and how much capacity the river took up in the stormwater system. StormSensor determined that the river infiltrated at least one mile inland during river stages at NOAA action levels. 

This was an important finding because, when the stormwater system is filled with river water, it does not have the capacity to handle the water it was built to manage – stormwater. Careful management of this delicate system is required to avoid flooding.

Figure 3: StormSensor data showing the River backing up into a stormwater system and gates being closed (highlighted in yellow) to manage water levels and increase capacity for storm flows (highlighted in green).

Management Impacts

After the first backflow event, several more were identified in the following months of winter 2020. Several rain events were forecasted during one particularly high river stage. 

The city was able to lower the gates in advance to strategically manage both the rising Mississippi River water and the imminent rainwater. 

Management Impacts

After the first backflow event, several more were identified in the following months of winter 2020. Several rain events were forecasted during one particularly high river stage. 

The city was able to lower the gates in advance to strategically manage both the rising Mississippi River water and the imminent rainwater. 

Figure 3: StormSensor data showing the River backing up into a stormwater system and gates being closed (highlighted in yellow) to manage water levels and increase capacity for storm flows (highlighted in green).

True End-to-End Solutions

While the intended use case of the flow data was for stormwater model calibration, the real-time data from StormSensor demonstrated value on its own for driving maintenance and helping with flood prevention, showing that monitoring is a BMP in and of itself.

True End-to-End Solutions

While the intended use case of the flow data was for stormwater model calibration, the real-time data from StormSensor demonstrated value on its own for driving maintenance and helping with flood prevention, showing that monitoring is a BMP in and of itself.

When the stormwater system is filled with river water, it does not have the capacity to handle the water it was built to manage: stormwater. Careful management of this delicate system is required to avoid flooding.

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At StormSensor, we believe that good decisions are driven by good data. As a team, we're bringing to life solutions that streamline insights for smarter decisions. If you're involved with water infrastructure, then send us a note. Tell us your challenges and learn more about how we're leveraging new technology to solve old problems.

Green InfrastructureIllicit Discharge DetectionCombined Sewer OverflowsStormwater Model ValidationUrban flooding managementCoastal management and sea-level riseCommercial stormwater managementOther