Embed Size (px)
Citation preview
Physical, chemical, and biological Physical, chemical, and biological characteristics of streams in characteristics of streams in
urbanizing areas near Denver, urbanizing areas near Denver, ColoradoColorado
Lori SpragueLori Sprague Robert Zuellig Robert Zuellig HydrologistHydrologist EcologistEcologist
U.S. Geological SurveyU.S. Geological SurveyDenver, CODenver, CO
May 2006May 2006
U.S. Department of the InteriorU.S. Geological Survey
Study Objectives•• Determine the effects of Determine the effects of
urbanization on hydrologic, urbanization on hydrologic, geomorphic, chemical, geomorphic, chemical, habitat, and biological habitat, and biological conditionsconditions
•• Determine the most important Determine the most important urban stressors related to the urban stressors related to the responsesresponses
•• Compare these responses Compare these responses over a range of environmental over a range of environmental settings throughout the Nationsettings throughout the Nation
Population in the South Platte River Basin increased by about 670,000 people from
1990 through 2000, to over 2.8 million
Nebraska
Colorado
Wyoming
Denver
South Boulder CreekSouth Boulder Creek19371937
Photos courtesy of USFShttp://bcn.boulder.co.us/basin/gallery/sboulder50yrs.html
South Boulder CreekSouth Boulder Creek19871987
Water management
Photos from http://bcn.boulder.co.us/basin/gallery
Site Selection
• Environmental characteristics –homogeneous environmental framework controlled for “natural”sources of variability
• Urban intensity –sites represented a gradient of urbanization (urban intensity index)
BoulderBoulder HendersonHenderson
Castle RockCastle Rock
ParkerParker
DenverDenverIdaho SpringsIdaho Springs
LovelandLoveland
Estes ParkEstes Park
Fort MorganFort Morgan
Fort CollinsFort CollinsSterlingSterling
CheyenneCheyenne
GreeleyGreeley
KerseyKersey
JulesburgJulesburg
North PlatteNorth Platte
Nebraska
Colorado
Wyoming
0 20 40 km
Stream with high-level urban intensity Urban Intensity Index = 100
Stream with mid-level urban intensity Urban Intensity Index = 40
Stream with low-level urban intensity Urban Intensity Index = 3
Study Design
• Biological characteristicsalgae, invertebrates, fish (summer low flow)
• Physical characteristicshabitat (summer low flow), streamflow, water temperature (continuous for 1 year)
• Chemical characteristicsnutrients, pesticides, sediment, chloride, sulfate, bacteria (spring and summer base flow)
Time and flow integrated chemical parameters
• Semi-permeable membrane devices (SPMDs)
• Placed at all 28 sites for 4 weeks
• Sequesters hydrophobic organics
• Mimics bioaccumulation in fish
Fish InvertebratesAlgae
Che
mis
try
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Urbanization
Conceptual model
Channelization, riparian clearingGreater extremes, more fluctuation
Pollutant generation, higher concentrationsFlas
hier s
tream
s, hig
her p
eak f
lows
Non
-nat
ive
spec
ies
Fish InvertebratesAlgaeC
hem
istr
y
Hyd
rolo
gy
Urbanization
Hab
itat
Tem
pera
ture
SedimentSulfate
Housing age
Population density
Base-flow chemistry• Suspended sediment related to housing age • Sulfate related to population density
Fish InvertebratesAlgae
Hyd
rolo
gy
Land coverRoad densityHousing age
Housing densityPopulation density
Urban intensity index
Urbanization
Hab
itat
Tem
pera
ture
PAHsChe
mis
try
Flashiness
SPMD chemistry• PAHs related to stream flashiness and many measures of urbanization • Variability in PAHs best explained by distance from stream to nearest road
Fish InvertebratesAlgae
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Urbanization explained variability of SPMD chemistry well, but not variability of spring and summer base-flow chemistry
SedimentSulfate
PAHsChe
mis
try
Flashiness
Land coverRoad densityHousing age
Housing densityPopulation density
Urban intensity index
Urbanization
Fish InvertebratesAlgae
Hyd
rolo
gyH
abita
t
Tem
pera
ture
HabitatNo strong relations between habitat and urbanization
Che
mis
try
Urbanization
HydrologyNo strong relations between hydrology and urbanization
Fish InvertebratesAlgae
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Water temperatureTemperatures related to high-intensity development near the stream
Duration of falling
temperatures
Che
mis
try
Land cover
Urbanization
Fish communities were related predominantly to housing age, fine suspended sediment, and chloride
Sediment
Chloride
Fish InvertebratesAlgaeC
hem
istr
y
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Housing age
Urbanization
Algal biomass was related predominantly to conductivity, nutrients, pesticides, the duration of high flows, and stream flashiness
ConductivityNutrientsPesticides
Fish InvertebratesAlgaeC
hem
istr
y
Duration of high flows
Flashiness
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Urbanization
Invertebrate communities were related predominantly to nutrients, pesticides, duration of high flows, and stream flashiness
NutrientsPesticides
Fish InvertebratesAlgaeC
hem
istr
y
Duration of high flows
Flashiness
Hyd
rolo
gyH
abita
t
Tem
pera
ture
Urbanization
SedimentSulfate
ChlorideConductivity
NutrientsPesticides
PAHs
?Water management
Other Factors
Fish InvertebratesAlgaeC
hem
istr
y
Duration of high flows
Flashiness
Hyd
rolo
gyH
abita
t
Tem
pera
ture Duration of
falling temperatures Land cover
Road densityHousing age
Housing densityPopulation density
Urban intensity index
Urbanization
Aquatic communities were related to chemistry and hydrology, but chemistry and hydrology generally were not strongly related to urbanization
Comparison – Total Pesticide Concentration
0.00
0.05
0.10
0.15
0.20
0.25
0 20 40 60 80 100Urban Intensity Index
Con
cent
ratio
n, μ
g/L
Denver
RaleighPortland
Atlanta
Con
cent
ratio
n, μ
g/L
Urban Intensity Index
0.0
0.5
1.0
1.5
2.0
2.5
0 20 40 60 80 100
Comparison – EPT Richness
RaleighPortland
Atlanta
05101520253035
0 20 40 60 80 100Urban Intensity Index
EP
T R
ichn
ess
Urban Intensity Index
Denver
EP
T R
ichn
ess
0
4
8
12
16
0 20 40 60 80 100
Comparison – EPT Richness
05101520253035
0 20 40 60 80 100Urban Intensity Index
EP
T R
ichn
ess
Conclusions• Aquatic communities were related to chemistry and hydrology,
but chemistry and hydrology generally were not strongly related to urbanization
• Commonly observed effects of urbanization (stream flashiness, increased chemical concentrations, fewer sensitive species) were not observed– Present-day aquatic communities are tolerant even in areas with
minimal development
– Water management?
• Does not mean urbanization is not affecting stream ecosystems– Likely multiple interacting stressors, including urbanization
– Protection of stream ecosystems may need to involve numerous strategies
CONTACT INFORMATION
Lori Sprague Robert Zuellig [email protected] [email protected]
303-236-4882 x262 303-236-4882 x278
U.S. Geological SurveyColorado Water Science Center
Denver Federal Center Building 53 MS 415Denver, CO 80225
