Background: Factsheet on the Effect of Urbanization on the Water Cycle

OEHHA has been working with the California Water and Land Use Partnership (CA WALUP, formerly the CA NEMO Partnership) to develop a series of factsheets that address the relationship between land use and aquatic resources. CA WALUP is an affiliate of the National NEMO Network
( The Partnership is a collaboration of various local, state, and federal agencies in California that provides assistance to local government through non-regulatory, research-based education and outreach programs that emphasize watershed science basics, natural resource-based land use planning, and better site design. Our goal is to educate land use decision makers and their staff about the link between land use and natural resource protection. Some of our activities to accomplish this objective are:

  • The development of technical tools: We are currently working on an Impervious Surfaces Analysis Tool which will facilitate the analysis of impervious cover associated with urbanization. It can be used for land use planning as well as an indicator of watershed health.
  • Education: We are developing a series of factsheets that addresses important issues, one of which is the ways in which urbanization alters the hydrological cycle. Future factsheets will address issues related to chemical, physical, and biological stressors of aquatic ecosystems, watershed indicators, better site design, and low impact development technologies.
  • Outreach: Holding workshops with city and county staff to promote an understanding of their decisions on aquatic resources and to provide the tools to support better decision-making.

In this first factsheet, developed by UCSB intern Emily Ruby, we address the issue of how urbanization alters the water cycle. Comments and questions are welcome.

1The National NEMO Network is a confederation of 32 educational programs in 31 states dedicated to protecting natural resources through better land use and land use planning. Each program is patterned after the original Nonpoint Education for Municipal Officials (NEMO) Program developed at the University of Connecticut, but has been adapted to reflect each state’s unique character, geography, and issues.