Comprehensive Watershed Management for Central Arizona ... · evolutionary processes. Values...
Transcript of Comprehensive Watershed Management for Central Arizona ... · evolutionary processes. Values...
Comprehensive Watershed Comprehensive Watershed Management for Central Arizona Management for Central Arizona Basins and the Valley of the SunBasins and the Valley of the Sun
Acknowledgements• Sponsors:• Central Arizona Project• City of Peoria • In-Kind Contributors:• Arizona Department of Environmental
Quality• City of Tempe• City of Scottsdale
Students
Leah Bymers (M.Sc.)Shelby Flint (M.Sc.)Chris Goforth (Ph.D)Emily Hirleman (Undergrad)Nick Paretti (M.Sc.)Chad King (Ph.D, Webmaster)
http://ag.arizona.edu/limnology/watersheds
New website• ag.arizona.edu/limnology/watershed
Background• Started examining watersheds
surrounding the Valley in 1996 (Lake Pleasant and the CAP Canal).
• Expanded to include Roosevelt, Apache, Canyon, Saguaro, and Bartlett in 1999.
• Currently assessing watershed health in all of the reservoirs surrounding the Valley including the Salt and Verde Rivers above and below them.
Rationale for a Watershed-Based Approach
• What are we really trying to measure?– “environmental health”, “ecological
integrity”, “biologic potential” etc.• How does this relate to drinking
water quality?– Striving for “ecological integrity”
inextricably brings us closer to “water quality” for municipal use.
Integrity Defined• General definition: “a systems
ability to generate and maintain biotic elements through natural evolutionary processes.” (Karr 1994).
• Integrity refers more to a system’s capacity and resilience than to its particular state.
Adopting integrity as a management goal does not imply maximizing any particular process rate (such as production) or compositional attribute (such as biodiversity); rather, it impliesmaximizing similarity to previously evolved ranges of states and process rates.
• Human impact on ecosystems typically stems from changes in physical, chemical, or biological attributes and from more than one stressor (i.e. cumulative effects and synergy).
• Consequently, restoring ecological integrity must be based on a broad, holistic perspective that recognizes myriad potential constraints.
• Water quality monitoring and assessment has traditionally been compartmentalized by the requirements of specific technical disciplines and has typically been undertaken at the site scale.
• Determining what integrity is for an ecosystem means gleaning from the data anthropogenic vs. natural stressors.
• Although natural systems may not be completely restorable, what often can be restored is a system’s ability to generate and maintain ecological elements through natural evolutionary processes.
Values Assessment• Management goals for watersheds
(e.g., exploitation, protection, restoration) are not selected by society scientifically, but are based on prevailing values.
• Scientists are rarely, if ever, charged with choosing large-scale management goals.
• The role of science in watershed management is:– To describe past, present, or future
ecosystem states.– Develop prescriptions for guiding
ecosystems toward societal-preferred states.
– Articulate the costs and benefits of maintaining ecosystems in selected states.
The integration of physical, chemical, biological, and
socioeconomic expertise needed to protect or restore an ecosystem makes watershed management a truly multidisciplinary endeavor
Specific Goals
• Assessment– Determine current physical, chemical,
and biological integrity of drainage basins to the Phoenix Valley.
• Prediction– Based on the above data, predict each
watersheds long- and short-term sustainability in light of various stressors.
Goals (cont.)• Recommendations
– Based on integration of all current and potential stressors, we will make recommendations to increase or sustain ecologic integrity (e.g., “water quality”).
Sampling/Research Design• Watershed monitoring/data
acquisition should account for spatial and temporal variation.
• The watersheds surrounding the Valley do not start with reservoir releases, the lowest reservoirs, or treatment plant intakes.
Spatial Variability in Reservoirs
Issues of Concern (e.g., “Stressors”
• Drought• Eutrophication• Rodeo-Chedeski Fire (and potential
for other wildfires)• Population Growth• Perchlorate• Algal Toxins• Disinfection by-products
Drought• Despite recent precipitation events,
hydrological drought persists in the southwest.
• Recent precipitation may bring short-term relief.
• Water year precipitation is still below average for most of the southwest.
• Since January, there have been increases in precipitation and percent of average snow water content.
• However, snowpack is/was still quite low in Arizona.
• Seasonal forecasts indicate an increased probability of above average temperatures across Arizona and New Mexico throughout the spring and summer.
• There is a slightly better-than-average chance of a weak El Nino episode developing during the second half of 2004.
Long-Term Climate Forecast• Unlike El Nino/La Nina events, which
usually last from 6-18 months, Pacific Decadal Oscillations (PDO) can last 20-30 years.
• Positive PDO phase = colder water in the North Pacific driving the jet stream well to the North of Arizona.
• Negative PDO phase = warmer water in the North Pacific enhancing the jet stream over Arizona.
Climate Summary• Possible short-term drought relief
due to El Nino events. • Long-term drought may continue
due to positive PDO phase.
Drought Effects on Reservoir Water Quality
• Warmer than normal temperatures earlier in the spring may lead to an earlier onset of thermal stratification.
• Prolonged stratification usually results in prolonged hypolimneticanoxia.
• Earlier than normal algal blooms may exacerbate thermal stratification.
• Increased strength of stratification, and subsequent hypolimneticanoxia, may mean bioavailablenutrients released from sediments and into downstream reservoirs, rivers or canals
• Sediment nutrient release may result in increases in primary production which may lead to increased strength of stratification which means more nutrients released from sediments etc. initiating a positive feedback mechanism.
•Decreased residence time in the reservoirs, may exacerbate the possible increases in primary production.
• Water quality problems associated with drought include increases in;– Disinfection by-products– Algal toxins– Tastes and odors– Salinity/TDS/Conductivity
http://www.rangeview.arizona.eduGeospatial Tools for Natural Resource Management
Drought, Wildfire, and Water Quality; The Rodeo-Chedeski Fire and Impacts on Roosevelt and Beyond
• As stated during the last meeting, the water quality effects on the Salt River and reservoirs below it from the Rodeo-Chedeski fire will be subtle and will occur in pulses.
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Overlay Chart
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Mean(Flow_cfs)
Mean(Turbidity_NTU)
Chart
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Mean(NH3-N (ppm))
Mean(NO3+NO2-N (ppm
Mean(Total P (ppm))
Mean(TKN (ppm))
Heavy nutrient loading following monsoon rains over burn area
But are present conditions different than post-fire
conditions?
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0 500 1000 1500 2000 2500 3000 3500 4000Mean(Flow_cfs)
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Pre- and Post-Fire Nutrient Loading
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.0 .5 1.0 1.5 2.0 2.5 3.0Y
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Mean(NH3-N (ppm))
Mean(NO3+NO2-N (ppm
Mean(Total P (ppm))
Mean(TKN (ppm))
• The detrimental effect of the pulses of suspended solids, nutrients, and other pollutants on the Salt River itself are relatively short-lived and will decrease over time.
• However, the detrimental effect on Roosevelt and downstream reservoirs will probably be longer-lived.
Pre- and Post-Fire Data from Roosevelt
Post-Fire
Pre-Fire
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0 1 2 3 4 5 6 7 8 9 10 11Mean(Chl a (mg/m3))
Chart
Nutrients
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.00 .05 .10 .15 .20Y
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Mean(Total P (mg/L))
Mean(Nitrate+Nitrite-N (mg/L
Mean(Ammonia-N (mg/L))
SRROOA
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-Fire
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/Pos
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0 1 2 3 4 5 6 7 8Y
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Mean(TOC (mg/L))
Mean(DOC (mg/L))
TOC/DOC
Trophic State Change Pre-and Post-Fire
Pre-FireComponents:Total N (mg/L)Total P (mg/L)Chl a (mg/m3)Ammonia-N (mg/L)Nitrate+Nitrite-N (mg/L)Prin Comp 1 Prin Comp 2 Prin Comp 3 Prin Comp 4 Prin Comp 5
Total N
Total P
Chl a (
Ammonia
Nitrate
x
y
z
2.1809 1.5404 0.6854 0.5933 -0.0000
EigenValue 43.618 30.808 13.708 11.866 -0.000
Percent 43.618 74.426 88.134100.000100.000
Cum Percent
Total N (mg/L)Total P (mg/L)Chl a (mg/m3)Ammonia-N (mg/L)Nitrate+Nitrite-N (mg/L)
Eigenvectors 0.65931-0.28956 0.27899 0.560960 29823
0.01028 0.48265 0.54587-0.348000 58981
0.13307 0.75836 0.09894 0.43061-0 46040
0.25863 0.32878-0.78384 0.011670 45878
-0.69326 0.00000 0.00000 0.615350 37516
Principal Components
Spinning Plot
Post-FireComponents:Total P (mg/L)Total NChl a (mg/m3)Ammonia-N (mg/L)Nitrate+Nitrite-N (mg/L)Prin Comp 1 Prin Comp 2 Prin Comp 3 Prin Comp 4 Prin Comp 5
Total P
Total NChl a (
AmmoniaNitratex
y
z
1.9932 1.2380 0.9528 0.6614 0.1546
EigenValue 39.864 24.761 19.055 13.228 3.092
Percent 39.864 64.625 83.680 96.908100.000
Cum Percent
Total P (mg/L)Total NChl a (mg/m3)Ammonia-N (mg/L)Nitrate+Nitrite-N (mg/L)
Eigenvectors-0.24002 0.61277 0.64158 0.39299 0.02887
0.00471 0.33665-0.05384-0.49295 0.80047
0.95491 0.12259 0.26204-0.03140-0.05889
0.15152-0.19989-0.24585 0.76603 0.53838
-0.08693-0.67542 0.67555-0.12157 0.25514
Principal Components
Spinning Plot
•Pre-fire trophic status = 43.143 or mesotrophic
•Post-Fire trophic status = 58.913 or eutrophic
TSI calculated using Kratzer & Brezonik, 1981
Summary• Probable continued drought.• The Salt River reservoirs continuing
to feel effects of Rodeo-Chedeskifire.
• Nutrient in-loading in Roosevelt may increase trophic status of downstream reservoirs.
• Earlier than normal onset of high temperatures may increase, and prolong, thermal stratification and hypolimnetic anoxia.
Questions?