National Water-Quality Assessment (NAWQA) Program
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Why study urbanization:
As land areas urbanize, stream ecosystems can be substantially altered.
Changes in the landscape as a watershed urbanizes may cause changes in stream
hydrology, water quality, physical habitat, and water temperature that are
known to have profound effects on aquatic communities of algae, invertebrate
and fish.
Understanding these interrelationships may contribute to informed decisions
that result in practical and effective water-resource management and strategies
that
protect and restore stream ecosystems.
How this study is unique:
Although there have been many studies
conducted on the effects of urbanization on streams, these studies
have different designs, limited geographic scope, and measure a
limited number of responses. In this study, each study adheres
to a nationally consistent design, and measures many response variables
using consistent sampling protocols and lab analytical procedures,
so that responses to urbanization can be compared locally, regionally,
and nationally.
Questions Addressed:
• How do stream ecosystems respond to
land-use changes associated with urbanization?
• How do these responses vary across metropolitan areas located in different
geographic settings?
Objectives:
• Determine the physical, chemical, and
biological responses of stream systems to a gradient of increasing
urban intensity.
• Determine the most important landscape features driving hydrologic, chemical,
geomorphic, habitat, and ecological responses to urbanization.
• Determine the physical and chemical factors associated with biological
responses.
• Compare these responses among metropolitan areas located in different
geographic settings (climate, geology, hydrology, biology, water use) across
the United States.
Study Design:
For each metropolitan area,
locate stream sites in 28-30 basins that have minimal natural variability
among them and represent a broad range of urban intensity from
low to high. Examine hydrologic, physical habitat, chemical, and
biological characteristics of the streams at these sites.
Timing and Locations:
Studies are conducted on a rotational
sampling schedule through 2012, including in Birmingham, Alabama;
Boston, Massachusetts; and Salt Lake City, Utah, in 2000; Raleigh,
North Carolina; Atlanta, Georgia; and Denver, Colorado, in 2003;
Dallas-Fort Worth, Texas; Milwaukee-Green Bay, Wisconsin; and Portland,
Oregon, in 2004; and Seattle, Washington, in 2007.
What we measure:
• Physical: physical habitat, stream
stage, and water temperature.
• Chemical: nutrients, pesticides, organic carbon, suspended sediment,
sulfate, chloride, dissolved oxygen, pH, specific conductance in water, and organic
contaminants and potential toxicity of extracts of semi-permeable membrane devices
(SPMDs - devices that concentrate trace levels of hydrophobic organic contaminants
from water).
• Biological: invertebrate, algae, and fish communities, and algal biomass
(chlorophyll a, ash-free dry mass).
U.S. Department of the Interior | U.S. Geological Survey
URL: http://water.usgs.gov/nawqa/urban/html/overview.html
Page Contact Information: Jerry McMahon
Page Last Modified: 17:21:15 Mon 23 Jun 2008
