Low Impact Development - LID

The Need for New Site Development Methods

Today, buildings and their surroundings are covered with impervious surfaces. Roofs drain into gutters and downspouts. Driveways, parking lots, roads and sidewalks are covered with asphalt and concrete. The ground around buildings is carefully sloped to help water run off.

Due to the impervious surfaces, water cannot absorb into the ground as readily as it did in the past. More runs into creeks than it did historically, and it does so faster, because the gutters and drainpipes speed the water to the creeks. After a rainstorm, the peak flow in a creek is far higher than it was historically, and the peak flow comes and goes quickly.

The high flows lead to creek erosion and destruction of habitat. In cities where the runoff is fed into wastewater treatment plants, this leads to increased water treatment expenses and potential.

The fast runoff also means there will be reduced water storage in the ground for native plants or landscapes.

Low Impact Development

Low Impact Development (LID) is an ever expanding group of solutions to slow runoff from developed areas. Porous asphalt, used in parking lots and roads, allows water to percolate through into ground rather than run off into creeks. Large parking lots are surrounded by open drainage swales. Drainage swales, landscaped with wetland plants, such as rushes and sedges, slow the runoff of water from the property. The swales allow water to diffuse into the water table as they create natural habitat.

Land can be resculpted to allow water to retain longer on the site. LID includes the use of wetlands, swales, creeks, retention basins, pools and lakes.

Green roofs are also part of Low Impact Development. During a storm, rainwater is temporarily held in the Green Roof soil. The water that cannot be held in the soil is gradually released into the drains and into the creeks.

Environmental Restoration, Native Landscaping and Low Impact Development

Low Impact Development creates new opportunities for native landscaping and restoration. Wetlands and riparian features are important additions to a designer's palette. They can be interwoven in a landscape with exciting and beautiful results.

Pacific OpenSpace works with Low Impact Development at a number levels. Our North Coast Native Nursery grows a full selection of native wetland plants, including rushes, sedges, wetland grasses and riparian plants.

Pacific OpenSpace works with landscape architects and environmental planners to develop restoration designs, restoration plans and management plans. Pacific OpenSpace restoration crews install and maintain natural landscapes for Low Impact Development projects.