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.

91202

120302

30603

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Dat

e

0 2000 4000 6000 8000 10000 12000 14000 16000

Overlay Chart

Y

Mean(Flow_cfs)

Mean(Turbidity_NTU)

Chart

91202

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Dat

e

0 5 10 15 20 25 30 35

Y

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?

71999

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50900

0 500 1000 1500 2000 2500 3000 3500 4000Mean(Flow_cfs)

91202

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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

Post

Pre

Pre

/Pos

t Fire

.0 .5 1.0 1.5 2.0 2.5 3.0Y

Y

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

Pre

/Pos

t Fire

0 1 2 3 4 5 6 7 8 9 10 11Mean(Chl a (mg/m3))

Chart

Nutrients

SRROOA

SRROOB

SRROOC

SRROOA

SRROOB

SRROOC

Pos

t-Fire

Pre

-Fire

Site

by

Pre

/Pos

t Fire

.00 .05 .10 .15 .20Y

Y

Mean(Total P (mg/L))

Mean(Nitrate+Nitrite-N (mg/L

Mean(Ammonia-N (mg/L))

SRROOA

SRROOB

SRROOC

SRROOA

SRROOB

SRROOC

Pos

t-Fire

Pre

-Fire

Site

by

Pre

/Pos

t Fire

0 1 2 3 4 5 6 7 8Y

Y

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?