Detailed Watershed Plans (DWPs) are being developed for each of the six established watersheds in Cook County. The purpose of each DWP is to identify the stormwater related problems in a watershed, develop alternative solutions to those problems, and then evaluate the alternatives to determine those that are most effective in addressing the watershed’s needs. When finalized, a DWP will contain a summary of the watershed’s areas of concern, and a listing of proposed regional capital improvement projects to address those concerns.

The watershed planning process consists of several steps:

• Gathering existing information on current watershed conditions, as well as past analyses that have been conducted.
• Analyzing the suitability of existing information.
• Determining what additional information is necessary but currently missing, and outlining procedures for obtaining this information.
• Obtaining the required new data.
• Developing hydraulic and hydrologic models of the watershed, using or updating existing models when possible.
• Identifying potential projects to address stormwater related issues such as flooding and erosion.
• Quantifying benefits and estimating costs of potential projects, as well as determining other non-cost factors to allow evaluation of alternative projects.

The first three steps, involving data gathering and analysis, must be completed in order to arrive at a reasonable estimate as to the scope of work and level of effort required for the remaining steps. Therefore, the watershed planning process is broken into two phases. Phase A primarily involves the information gathering tasks necessary to delineate the scope of work for Phase B, in which the generation of new data, modeling, and project development and evaluation will take place.

The District has incorporated a technical review of the hydrologic and hydraulic models developed for the watersheds into the DWP development process. This review is being performed by an experienced engineering consulting firm that is not associated with the firms developing the watershed models.