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Indiana Harbor and Canal
Dredging and Disposal Project
Note: In July 2021, USACE began the Phase 2 dike project to expand the CDF exterior dikes by 11 feet to maintain sufficient storage capacity for the intended project life, consistent with the original project authorization and plan. Dredging is not being performed while construction is underway. As a result, PID monitoring and turbidity monitoring are on hold. Real-time air monitoring continues in temporary locations off dike at onsite northeast and southeast stations using the M1 and M2 monitors (AM1 and AM2). The M3 and M4 monitors are not operating during dike expansion. Ambient air monitoring continues in one southwest location off dike (CON-SOUTH) and at the school. Dredging activities are anticipated to resume in 2024. More information »

Water Quality Monitoring Data

Maximum daily Dredge Contribution values and their associated sensor data
Date Range
Current-Based Result


Every record by year in comma-separated format (CSV)

All values for turbidity are in NTU.

About this Data

During dredging, there are two buoys and a water current detector positioned around the dredging area (dredge). One buoy is positioned upstream of the dredge and the other downstream of it. The water current detector identifies which direction the water is flowing past the dredging area so that “upstream” or “downstream” can be assigned to each buoy.

Each buoy has two turbidity sensors, one near the surface of the water (high) and another lower down (low). Turbidity readings are reported every fifteen minutes for each of the four sensors (DownstreamHigh, DownstreamLow, UpstreamHigh, UpstreamLow).

The dredge contribution is the amount of turbidity that is caused by dredging activities. The dredge contribution is calculated as the largest value of the downstream sensor minus the smallest value of the upstream sensor. The issues in the table will alter the turbidity value as noted.

Issue Dredge Contribution
Negative dredge contribution 0
Water current detector indicates no water flow 0
Upstream sensor is offline Largest value of the downstream sensor is used
Downstream sensor is offline (no data collected, dredging should be stopped) Offline

The "Flags" column indicates the status of the sensors at the time of the reading:

Flag Definition
S At least one of the sensors was offline
C Current detector indicated no water flow
M Current detector is offline (upstream/downstream is not applicable, dredge contribution is largest of all sensors)

Other Water Quality Data Sources

The U.S. Geological Survey (USGS) also conducts turbidity monitoring in the Indiana Harbor and Canal (IHC) at USGS gauge 04092750 (map).

USGS Turbidity Data

Turbidity data is available for daily maximum, daily minimum, and daily mean FNU statistics from March 2011 to the present. Recent USGS monitoring data is considered provisional until the data quality can be verified.

USGS Turbidity Data

Other USGS Water Quality Data

In addition to turbidity data, USGS monitors other water quality parameters at the Indiana Harbor Canal gauge, including chemical parameters and streamflow statistics. These archived data and annual reports are available on the USGS web site.

Other USGS Water Quality Data

While USACE is working with USGS to correlate the dredging turbidity data with the USGS gauge to monitor dredging operations, several factors may affect the two turbidity monitors differently, including but not limited to:

  • The distance of the dredging operation from the USGS gauge
  • Whether the dredging operation is upstream or downstream from the USGS gauge
  • Stream flow direction and magnitude
  • Vessel traffic, discharges, or other factors which could locally affect localized turbidity readings
  • Turbidity monitor instrument type, calibration, or data collection frequency