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Queen City Dam Hydrology Study

Project Details

The North Dakota State Water Commission retained the services of Apex Engineering in May of 2016 to study the hydrology of Queen City Dam. Queen City Dam was classified as a high-hazard dam owned and maintained by the City of Dickinson. The purpose of the project was to provide a hydrologic analysis of the dam to determine dam safety and to perform subsequent dam-break modeling.

The primary use of Queen City Dam is as a recreation facility. The principal spillway is an uncontrolled drop inlet. The riser structure is a 9 foot by 5-foot concrete box, with a headwall against the upstream face of the dam, resulting in a weir length of 23 feet.

Apex’s tasks included:

  • Developing a hydrologic model of the watershed above Queen City Dam using HEC-HMS.
  • Simulating the inflow to the dam resulting from the Probable Maximum Precipitation.
  • Determining the percent of the PMP the dam can pass without overtopping.
  • Determining the capacity of the principal spillway, and evaluate the effect of high tailwater on the principal spillway capacity.
  • Determining if the dam meets current spillway criteria for a class IV, high hazard dam.


The Queen City Dam study resulted in the following:

  • Urbanization has increased the drainage area from 3.82 mi2 to 4.13 mi2.
  • A survey of the crest of the dam, shows that most of the dam is lower than the design elevation.
  • The principal spillway does not meet the criteria for a Class IV dam as required by the North Dakota Dam Design Handbook.


The dam does not meet the auxiliary spillway criteria for a Class IV dam as required by the North Dakota Dam Design Handbook.

Project Type

Water Resources

Hydrologic Analysis


ND State Water Commission


Dickinson, ND

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