Lecture 40

Lecture 40

Ground-Water Management

Fetter 12

Usually very difficult to measure recharge.

	Measure many of the parameters directly - precipitation, stream flow, evaporation
	Ground-water flow computed from measured properties and models.

What are the components that need to be measured?

Ground-water recharge = (pptn + s-w inflow + imported water + ground water inflow) -

(ET + Evap from open bodies water - exported water + ground water out flow)

changes storage

Aquifers are used for:

1) Management

2) Supply water

3) Transmit water - pipeline

4) Mined

5) Filter (vadose zone)

6) Energy - heat pumps

7) Storage - CAP water - water banking

Safe Yield

First defined Lee, 1915 - amount of water that can be pumped "regularly and

permanently without dangerous depletion of storage reserve"

Meizner, 1923 - "the rate at which water can be withdrawn from an aquifer for

human use without depleting the supply to the extent that withdrawal at this

rate is no longer economically feasible."

considers economic value and value to humans

Conkling, 1946 - annual extraction that doesn’t:

1. exceed annual recharge

2. lower water table so that the permissible cost of pumping is exceeded

3. lower water table so as to permit intrusion of water of undesirable quality

Banks, 1953 - water rights

All include hydrologic, economic, quality and legal consideration.

All neglect - environmental change resulting from change in steady state

condition.

Salt River Project

The Salt River Project (SRP) manages a large water storage and distribution

system supplying raw water to a 240,000-acre service area within metropolitan

Phoenix, Arizona. Surface and ground-water supplies are routed through an extensive

open canal system spanning nearly 135 miles in the metro Phoenix area. Canal water is

distributed to users for agricultural, urban, and municipal purposes. In 1994, SRP

upplied approximately 1,000,000 acre-ft of water. Approximately 59% was surface

water from the Salt River watershed, 27% was from the Verde River watershed, 9%

was from ground water, and 5% was from the Central Arizona Project.

The CAP is a canal connecting the Colorado River with Phoenix and Tucson. The canal

was fully functional in 1991. The purpose of the CAP is to reduce the amount of

ground-water withdrawals in the basins surrounding Phoenix and Tucson. The CAP is

capable of delivering 1.5 million ac-ft. The total allocation of Colorado River for Arizona

is 2.8 million ac-ft. The CAP’s conveyance system is 336 miles long and cost $3.4 billion.

The 1980 Goundwater Management Act dictated that Arizona create water conservation

areas for all ground-water users. These areas are called Active Management Areas. The

goal of each AMA is to stop net declines in ground-water levels, or only use as much ground

water as is naturally recharged. During periods of the year when the full allocation of Colorado

River water is not used (in the winter) the water is recharged into aquifers through recharge

lagoons and galleries. This increases water in storage in the aquifers so that it can be used later.

One of the problems facing ground-water supplies used by SRP is the degradation of water

quality. Of the 224 wells used by SRP in 1994, 20 (8%) had organic contaminant

that exceeded U.S. EPA drinking water standards. Another 41 (16%) had concentrations

of organic contaminants that did not exceed drinking water standards.

Sample Comparison of Permit Requirements for Discharge Water
Permit condition	NPDES	APP	Reuse
Biomonitoring	yes	no	no
Sampling frequency	twice monthly	quarterly	varies from continual for fecal coliform to biennial
Biological components	yes	no	yes
Organic chemical	Pentachlorophenol, Phenol, Tetrachloroethylene, 2, 4, 6 Trichlorophenol, 2-Chlorophenol, 2, 4-Dichlorophenol, 2, 4-Dimethylphenol, 2, 4-Dinitrophenol, 3-Methyl-4-chlorophenol, 2-Methyl-4, 5-Dinitrophenol, 2-Nitrophenol, 4-Nitrophenol	Endrin, Lindane, Methoxychlor, Toxaphene, 2, 4-Dichlorophenoxyacetic acid, 2, 4, 5-Trichlorophenoxypropionic acid, Trihalomethanes, Benzene, Vinyl chloride, Carbon tetrachloride, 1, 2-Dichloroethane, Trichloroethene, 1, 1-Dichloroethylene, 1, 1, 1-Trichloroethane, 1, 4-Dichlorobenzene	none
Phenols	yes	no	no
Chlorine	yes	no	no
Others	arsenic, cadmium, chromium, copper, cyanide, lead, mercury, selenium, silver, zinc	arsenic, barium, cadmium, chromium, lead, lindane, mercury, Selenium, silver, barium, nitrite as nitrogen, and fluoride	none
Point of compliance	outfall	wells downgradient in aquifer	outfall
Term	5 years	life of facility	5 years
Other	turbidity, pH, solids, BOD	groundwater monitoring	contract with user

This table was compiled from information from permits held by the City of Tucson

and Pima County for wastewater from a county-owned treatment plant. The intent is

to give an indication of the types of requirements in each type of permit. Permits from

other facilities would have different conditions.

	NPDES Permit for Pima County Ina Road Treatment Plant
	APP Permit for the City of Tucson Sweetwater Underground Storage and Recovery Project
	Reuse Permit from the City of Tucson Wastewater Reclamation Treatment Plant

ENV 302 - Lectures