Stormwater Management in Michigan: Why LID? - Low Impact Development and Sustainable Stormwater Management - page 220

Table 2.1 Pollutant Removal Table (in percentages)

Stormwater Water Stormwater

Infiltration Stormwater Ponds Filtering Quality Dry

Pollutant Practices Wetlands Wet Practices Swales Ponds

Total
Phosphorus

70 49 51 59 34 19

Soluble
Phosphorus

85 35 66 3 38 6

−

Total Nitrogen 51 30 33 38 84 25

Nitrate 82 67 43 14 31 4

−

Copper N/A 40 57 49 51 26

Zinc 99 44 66 88 71 26

TSS 95 76 80 86 81 47

Source: ''National Pollutant Removal Performance Database for Stormwater Treatment Practices''.
Center for Watershed Protection, June 2000.

LID focuses on the following stormwater outcomes, described in more detail in
Chapter 9:

• Preventing flooding
• Protecting the stream channel
• Improving and protecting water quality
• Recharging groundwater.
Chapter 9 describes recommended criteria that communities and/or develop-
ers may use at the site level to implement LID designs. This may also be used at
the community level to develop standards to ensure that development meets the
outcomes listed above.
Infiltration practices often associated with LID provide enhanced water quality
benefit compared to many other BMPs. Percent of pollutant removal for various
LID practices is shown in the table below.

Principles of LID

Successful application of LID is maximized when it is viewed in the context of the
larger design process. This process is reflected in a set of principles used to guide
development of this manual.

• Plan first
• Prevent, then mitigate
• Minimize disturbance
• Manage stormwater as a resource—not a waste
• Mimic the natural water cycle