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Step 2

Map drainage patterns, and determine connected versus disconnected impervious cover.

In order to help choose and prioritize stormwater practices, it is important to understand drainage patterns as accurately as possible. Urban drainage is often so highly engineered that surface topography alone is not enough to determine drainage patterns.

When determining where the water goes, a critical task is to categorize IC as either “connected” (leading more or less directly into the drainage system) or “disconnected” (draining to a pervious area and thus not contributing to stormwater runoff). Disconnected IC can be pretty much taken out of the equation. And, unless you plan to rip up large swaths of road, disconnecting connected impervious cover is likely to be the major focus of your plan. Watch video "Is your IC connected?"

Getting a good handle on drainage is more of an art than a science. The best way is to combine field checking with map analysis. See below.

Is your IC Connected?

Categorize your IC: learn to distinguish “connected” from “disconnected” IC.

videoIconVenture into the world of IC with Dr. Mike Dietz

Even when you know what you’re looking for, getting a good handle on drainage can be more of an art than a science. The best way is to combine field checking with map analysis. See below for tips on both.

Map Analysis

Mapping your drainage: learn how to use the CT ECO online mapping site to get a handle on your drainage.

videoIconMapping Drainage Areas in Your Watershed Video


videoIconExamples of Data Layers You'll Need to Map Your Drainage


Field Checking

Field checking: tips for what to look for when you’re out there wandering the watershed.

videoIconBurrowing into the Storm Drain System Video


videoIconThe Fine Art of Windshield Surveys Video