SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Stretching our Water SuppliesSouth Metro Denver Area

Gunnison Water ConferenceJuly 28, 2004

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

South Metro Denver Area

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

How do we Stretch Water Supplies?

• Demand Management

• Reuse

• Resource Management

• Conjunctive Use

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

What is meant by “Conjunctive Use”?

• Conjunctive Use is the combined use of different sources or types of water supplies to maximize use or efficiency.

• Conjunctive Use in the South Metro area is the combination of deep non-tributary ground water with surface water sources to maximize the yield of surface water.

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Why is “Stretching the Resource” so important for the South Metro area?

• Ground Water is not a renewable water supply

• Artesian Head in the Aquifers is rapidly depleting

• Production levels are dropping

• Water cannot be produced at rates sufficient to support urban development

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

What’s the Real Story?

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Aquifer Water Levels

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Ground Water Pumping – Existing Conditions

600

ft3 0

0 ft

regional head

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Ground Water Pumping – Future Projections

50 f

t3 0

0 ft

regional head

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Ground Water Pumping RatesAlternative 1A

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Cross Section Upper Arapahoe Aquifer along Row 58

4000

4200

4400

4600

4800

5000

5200

5400

5600

5800

6000

8 18 28 38 48

Column

Ele

vati

on

(ft

)

2000 Head (ft)

2030 Head (ft)

2050 Head (ft)

Aquifer Top

Aquifer Bottom

Inverness

Centennial

ECCV

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Stretching through Conservation

• Management through Awareness

• Management through Pricing

• Reductions through Landscape Changes

• Typical Reductions of 20%

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Stretching through Reuse

• Augmentation (easy reuse)

• Non-potable irrigation (successful in commercial/public areas)

• Indirect potable reuse (ACWWA/Cottonwood invest in 12 MGD plant)

• Reuse can double supply

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

INDIRECT POTABLE REUSE

WaterSupply

Augmen

ted

Supply

Return

Flow

WWTP

WTP

Riv

erHomeUse

Irrigation

Wastew

ater

Effluent R

eturn

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Stretching through Resource Management

• Pooling of Resources

• Pooling of Facilities

• Cooperation in Use of Water Rights

• Upper Cherry Creek Water Association increases yield by about 30%

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Stretching through Conjunctive Use

• Surface Supplies vary from Year to Year

• Water Supply must be available every year

• Either– Only develop dry yield waterOr– Develop wet year yield by

supplementing from other sources

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Water Supply Sources

• Denver Basin Ground Water• Surface Supplies (So. Platte, Plum Creek, Cherry Creek,

Denver Contract)• Augmentation• Reuse

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Flow History of South Platte RiverRENEWABLE WATER AVAILABILITY

SOUTH PLATTE RIVER

0

50000

100000

150000

200000

250000

300000

350000

1947 1951 1955 1959 1963 1967 1971 1975 1979 1983 1987 1991

Year

An

nu

al

Flo

w (

cfs)

WET

DRY

Average Flow = 146,366 cfs

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Flow History of Blue RiverRENEWABLE WATER AVAILABILITY

BLUE RIVER

0

50,000

100,000

150,000

200,000

250,000

1947 1951 1955 1959 1963 1967 1971 1975 1979 1983 1987 1991

Year

An

nu

al

Flo

w (

cfs)

Average Flow = 110,627 cfs

DRY

WET

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

South Metro

Aquifer

Average Wet Drought

Denver CSA

Current Operation

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Denver CSA

South Metro

Aquifer

Average Wet Drought

Conjunctive Use Operation

South Metro

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Potential “Conjunctive Use” Yield for South Metro Area

Free River Only Scenario: Average Annual Delivery vs. Diversion Capacity

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0 300 600 900 1,200 1,500 1,800 2,100

Diversion Capacity, cfs

Av

era

ge

An

nu

al D

eliv

ery

, ac

re-f

ee

t

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

Water Supply Comparisons

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

The Importance of Conjunctive Use

• Conserves the Ground Water

• Allows for Ground Water Replenishment

• Makes use of wet year water without major storage

• Makes effective use of the Ground Water

SOUTH METRO WATER SUPPLY STUDY DECEMBER 2003

The Formula for Water Supply in the South Metro Area:

• Conservation Every Year

• Major Reuse (non-potable and indirect potable)

• Full Use of Local Surface Water Supplies

• Sustainable Use of Ground Water

• Resource Management

• Conjunctive Use