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Low Impact Development

What is it?

Low Impact Development (LID) is a stormwater management approach that works with nature to manage rainwater as close to where it falls as possible.

Low Impact Development focuses on slowing rainwater down, soaking it up, and using soil and plants to clean it before it gets to our waterways.

The Problem with Runoff

As water runoff flows across the ground's surfaces, it picks up what it touches and becomes polluted.

Unless something is done, the runoff filled with dirt, chemicals, and other pollutants contaminates our streams and waterways.

Runoff can also cause flooding damage in lowland areas.

What is Stormwater runoff?

Stormwater runoff is rain or snowmelt when it flows over land or paved surfaces and is not absorbed into the ground. 

Skagit County is subject to a National Pollutant Discharge Elimination System (NPDES) permit that can result in significant penalties upon the County and property owners if polluted water is discharged to ditches or streams. Stormwater management is governed by Skagit County Code Chapter 14.32, which received major revisions effective January 1, 2016. All land disturbing activity (except when vested before that date) must manage stormwater consistent with this chapter.               


All land on earth is a watershed (the land area down which all water flows). Water flows down over land until it is absorbed into the soil or caught in a low spot like a lake or the sea. 

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The Solution

Slow the flow of water, so it can be soaked into and filtered through the soil to clean it before it gets to our waterways. That is the goal of Low Impact Development. 

The Basics of LID

  • Minimize site disturbance and reduce impervious surfaces where feasible (don’t pave over the whole site if you don’t need to).

  • Protecting and restoring native soils and vegetation (Don't remove native trees and shrubs unnecessarily. Do not disturb or compact soil unnecessarily.)

  • Manage stormwater close to the source (don’t let the water leave the site).

  • Scatter Integrated Management Practices (IMPs) throughout your site that infiltrate, store, evaporate, and/or detain runoff close to the source.

Low impact development promotes the view of rainwater as a resource to be preserved and protected, not a nuisance to be eliminated. 


When implemented broadly, LID can mitigate the urban heat island effect, save energy, reduce air and water pollution, improve neighborhood aesthetics, increase groundwater recharge, and increase habitat for wildlife, such as birds and pollinators.

LID is economical

LID is as cost-effective as—if not more cost-effective than—conventional approaches in part because of the long term savings in maintenance and repair. Not to mention the aesthetic benefits.


Raingardens attract dragonflies, frogs, and birds

Water in a properly designed rain garden will not last more than 2 days after most storms which is not long enough for mosquitoes to use, but it will be enjoyed by many of our wild friends.

Rain gardens are designed to be self-sufficient

Some weeding and watering will be needed in the first two years, and perhaps some thinning in later years as the plants mature, but a well-planned raingarden can be maintained with little effort after the plants are established.

Why aren't more people using LID techniques?

I don't know! Maybe they haven't heard about them yet.  We need to spread the word!

LID Techniques Can Be Applied at Any Development Stage

•   In undeveloped areas, an LID design can be incorporated in the early planning stages. Typical new construction LID techniques include protecting open spaces and natural areas such as wetlands, installing bioretention areas (vegetated depressions) and reducing the amount of pavement.

•   In developed areas, communities can add LID practices to solve problems and provide benefits such as being used to buffer structures from roads, enhance privacy among residences, and for an aesthetic site feature.  Typical post-development LID practices range from directing roof drainage to an attractive rain garden to retrofitting streets with features that capture and infiltrate rainwater

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Is LID required?

LID is the preferred approach to stormwater management countywide.

Inside the NPDES Permit Area and the Special Flood Hazard Area, LID techniques are required unless not feasible. When required, applicants must use the techniques in the Low Impact Development Technical Guidance Manual for Puget Sound (Puget Sound Partnership and WSU Extension, 2012) unless the Administrative Official determines the techniques as not feasible.

Our Partners:

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