U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2017–3014

February 2017

National Water–Quality Program

The California Stream Quality Assessment

Printed on recycled paper

In 2017, the U.S. Geological Survey (USGS) National Water-Quality Assessment 

(NAWQA) project is assessing stream quality in coastal California, United States. The 

USGS California Stream Quality Assessment (CSQA) will sample streams over most of 

the Central California Foothills and Coastal Mountains ecoregion (modified from Griffith 

and others, 2016), where rapid urban growth and intensive agriculture in the larger river 

valleys are raising concerns that stream health is being degraded. Findings will provide 

the public and policy-makers with information regarding which human and natural factors 

are the most critical in affecting stream quality and, thus, provide insights about possible 

approaches to protect the health of streams in the region.

Figure 1. California 

Stream Quality 

Assessment study 

area and provisionally 

selected sampling 

sites; the boundary 

is based on the 

U.S. Environmental 

Protection Agency 

level III ecoregions 

of the United States 

(https://www.epa.gov/

eco-research/leveliii-and-iv-ecoregionscontinental-unitedstates).

The CSQA study will be the fifth regional assessment of streams by the 

NAWQA project, and it will be similar in design and scope to the others: the Midwest 

in 2013, the Southeast in 2014, the Northwest in 2015, and the Northeast in 2016 

(http://txpub.usgs.gov/RSQA/).

Objectives

1. Determine the status of stream 

quality—contaminants, nutrients, toxicity, sediment, flow, 

habitat, and biological communities—across the region. 

2. Evaluate the relative influence 

of the measured chemical and 

physical stressors on biological communities in the streams 

sampled.

3. Evaluate relations between 

measured stressors and 

biological communities and the 

natural and anthropogenic characteristics of the watersheds. 

4. Develop models and management tools to predict stressors 

and ecological conditions in 

wadeable streams across the 

region.

Approach

Eighty-five sites have been provisionally selected to be sampled for up to 

6 weeks in March, April, and May 2017 

(fig. 1). This water-quality index period 

will culminate with an ecological survey 

of habitat, algae, benthic invertebrates, 

and fish at all sites. Sediment will be 

collected during the ecological survey 

for analysis of sediment chemistry and 

toxicity. Final site selection will depend 

on streamflow conditions during winter 

2017. Sampling is planned at 44 sites 

in watersheds with urban land uses, 28 

sites in watersheds with mixed urban 

and agricultural land uses, 2 sites in 

watersheds with agricultural land uses, 

and 11 sites in undeveloped watersheds. 

The resulting data should span a wide 

range of stressors, allowing the effects of 

those stressors on stream ecology to be 

better understood.

Base modified from U.S. Geological Survey and other Federal and State digital data, various scales; Albers 

Equal-Area Conic projection, Standard parallels are 29° 30” and 45° 30”, Central meridian -121°; North American 

Datum of 1983. Land cover modified from National Land Cover Database 2011. Base-map image is the intellectual 

property of Esri and is used herein under license. Copyright © 2014 Esri and its licensors. All rights reserved.

123°

39°

38°

37°

36°

35°

122° 121° 120°NEVADA CALIFORNIA

PACIFIC

OCEAN

0 50 MILES

0 50 KILOMETERS

EXPLANATION

Site type

" Urban

Agricultural

Reference

Mixed

!

#

#

Land cover

Central Valley

Urban

Grasslands and other

Forest

Pasture/hay

Cultivated crops

Water or wetlands
Study Components

Assessing Ecological Condition—Algae, benthic 

macroinvertebrate, and fish communities will be 

sampled and physical habitat assessed once at all 85 

sites in April or early May 2017. Samples will be collected along multiple transects within the stream reach 

following USGS NAWQA protocols. 

Water Sampling—Using depth- and 

width-integrating methods, water samples 

will be collected weekly for 6 weeks at 

most sites and at the 12 reference sites for 

4 weeks preceding the ecological sampling. 

The samples are to characterize the water 

chemistry during late winter and early 

spring, a period of potential concern for 

chemical runoff.

Water samples will be analyzed for nutrients, 

suspended sediment, major ions, and pesticides and 

pesticide degradates. Some samples also will be analyzed for mercury, pharmaceuticals, and wastewaterindicator compounds.

Integrated Water Sampling—Passive polar 

organic chemical integrative samplers (POCIS) will 

be deployed in streams at all 85 sites for the 6-week 

water-sampling period to collect dissolved chemicals 

from stream water. These time-integrating samplers 

will be used to characterize longer-term chronic 

exposure of organisms to contaminants. The POCIS 

samples will be analyzed for pesticide and 

pharmaceutical compounds. 

Biofilms, colonies of microorganisms attached to stream substrates, will be 

sampled at most sites by deploying ceramic 

tiles in the streams for the 6-week watersampling period, allowing time for the 

biofilms to accumulate on the tiles. Samples 

will be analyzed for pesticides, with a particular focus on pyrethroid insecticides. 

Streambed Sediment Sampling—Streambed 

sediment will be sampled coincident with the ecological sampling at all 85 sites. Surficial bed sediment will 

be collected from depositional areas and analyzed for 

trace elements, radionuclides, pesticides, polycyclic 

aromatic hydrocarbons (PAHs), halogenated organic 

compounds (compounds containing chlorine or bromine atoms, such as DDT), wastewater-indicator compounds, and hormones. Not all analyses will be done at 

all sites. Sediments tend to accumulate different contaminants than does water and can provide additional 

understanding of contaminant effects on organisms.

Geochemical Analysis of Suspended Sediment— 

Suspended sediment traps will be installed at 7 of the 

85 sites to collect composite samples of suspended 

sediment. High concentrations of suspended sediment 

adversely affect stream health, and source identification can provide insight toward appropriate mitigation 

strategies. Geochemical analysis of suspended sediments will be used to identify their potential origins. 

Toxicity Testing—Bed-sediment samples from 

all sites will be tested using standard wholesediment toxicity tests with amphipod crustaceans 

(Hyalella azteca 28-day exposures) and midge larvae 

(Chironomus dilutus 10-day exposures) to measure 

potential effects of contaminants on survival and 

growth. Amphipods and fish are sensitive to many 

contaminants, notably some current-use insecticides 

and PAHs.

Continuous Monitoring—Water level and temperature will be monitored continuously at all 85 sites 

across the region. USGS currently operates real-time 

streamflow-gaging stations at approximately 30 of the 

provisionally selected sites.

Daily Pesticide Sampling—Small-volume automated pesticide samplers will be deployed at seven 

streams to better assess temporal variations in concentrations of pesticides and pesticide degradates. Five of 

these streams are among the 85 CSQA sites, and two 

are in the Central Valley (sites not shown in fig. 1). 

The samplers will collect daily and weekly composite 

samples that will be analyzed by the U.S. Environmental Protection Agency’s Office of Pesticide Programs. 

Results will provide valuable information for determining short-term acute exposure of aquatic organisms 

to pesticides and for optimizing temporal sampling 

strategies.

Cyanobacterial Toxins—Harmful blooms of 

cyanobacteria (also called blue-green algae) are of 

considerable concern, and relatively little is known 

about their occurrence in small streams. A reconnaissance survey of microcystins, toxic chemicals produced 

by cyanobacteria, will be carried out in CSQA streams 

in May 2017.

Mercury in Fish—Mercury contamination is a 

widely recognized concern in the coastal ranges of California. Fish from most of the 85 sites will be analyzed 

for total mercury, and fish from a subset of sites will 

be analyzed for isotopes of mercury using a technique 

that can indicate the sources of the mercury. The study 

could provide new insight into occurence, processes, 

and sources of mercury in coastal California fish given 

the large number of samples and diversity of stream settings being investigated.

References Cited

Griffith, G.E., Omernik, J.M., Smith, D.W., Cook, T.D., 

Tallyn, E., Moseley, K., and Johnson, C.B., 2016, 

Ecoregions of California (poster): U.S. Geological 

Survey Open-File Report 2016–1021, with map, scale 

1:1,100,000, http://dx.doi.org/10.3133/ofr20161021.

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

https://doi.org/10.3133/fs20173014

For Additional Information

Visit the NAWQA website to access reports, water-quality 

data, and maps: http://water.usgs.gov/nawqa

Or contact: 

Peter Van Metre 

(512) 927-3506 pcvanmet@usgs.gov

Amanda L. Egler

(916) 278-3210 alegler@usgs.gov

Jason May

(916) 278-3079 jasonmay@usgs.gov

Photograph by Alan Cressler, 

U.S. Geological Survey

Photograph by Amanda Egler, 

U.S. Geological Survey