October 14, 2002

The Colorado Public Interest Research Foundation

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Executive Summary

Sprawl results in the inefficient use of our water resources, decreased water quality, and higher costs for water and sewer needs. While there has been much discussion about the loss of open space, increased traffic congestion, and the air pollution resulting from sprawl, we have only recently begun to discuss sprawl's impact on our water supply. The fact is that we live in a semi-arid state with limited water resources and sprawl wastes those resources. Colorado's incredible population growth combined with the state's lack of growth management policies has affected both the quantity and quality of our state's limited water supplies, as well as the costs of providing water to residents.

This report shows the following:

1. Sprawl stresses our limited water supply. In fact, high-density planned development may use up to 35 percent less water than low-density sprawling development.

2. Sprawling development patterns negatively impact water quality. A one-acre parking lot produces about 16 times the volume of runoff that comes from a one-acre meadow. This runoff transports various pollutants into the water supply including: sediment, nitrogen, phosphorus, organic carbon, copper, zinc, lead, petroleum hydrocarbons, and pesticides.

3. Poorly planned growth results in increased infrastructure costs for water and sewer needs. Low-density suburban development can cost two to three times more in infrastructure costs than a traditional community.

Our water supplies have been strained by sprawling development patterns resulting from a lack of long term water and land use planning. Colorado has been approving substantial numbers of large-lot subdivisions that require large amounts of water to sustain their lawns and water intensive landscaping. In fact, over half of the total residential water consumption in Colorado is due to outdoor uses. Additionally, numerous communities across the state are subject to covenants that require water intensive landscaping or create obstacles to the use of more water efficient alternatives. Finally, in many of our fastest growing communities, increased water supply demands are being met with nonrenewable groundwater sources. Integrated water and land use planning can help to alleviate the state's water quantity issues.

In addition to straining our available supply, sprawl is also affecting our water quality. Covering natural areas with impervious surfaces such as roads, parking lots, and rooftops causes runoff to reach our streams and rivers more quickly and in a more polluted condition. Many of the water quality problems associated with sprawl are a direct result of the increased reliance on the automobile that characterizes these sprawling development patterns by increasing the need for roads and parking lots. Roads and parking lots send polluted water directly into our streams and rivers and transportation-related air pollution can also finds its way into water bodies. Clustering development and providing buffer zones around water bodies can help reduce these impacts.

Sprawl results in increased costs for water-related infrastructure. As development spreads out and is covered with impervious surfaces, water and sewer costs skyrocket. The increased demand created by sprawl also results in efforts to push costly and environmentally destructive large storage and diversion projects on Colorado. Planning for water needs in relation to land use decisions can help reduce expenses for water and sewer systems as well as reduce the need for new storage projects by promoting more efficient use of the water resources we already have.

Colorado can protect our water in terms of quantity and quality and reduce water related infrastructure costs by managing growth. A statewide water plan that links water quantity and quality planning to land use planning would ensure that sprawl-related water impacts are addressed before new development is put in place. Reducing lot sizes, utilizing climate appropriate landscaping, promoting compact development patterns, and reducing impervious surface ratios can help protect the quantity and quality of our water supply as well as reduce infrastructure costs.