Form 9-01 1

UNITED STATES
DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY
WASHINGTON. D.C. 2O24§fe

Water Resources Division

ESTIMATED EXISTING AND POTENTIAL GROUND-WATER STORAGE
IN MAJOR DRAINAGE BASINS IN OREGON

By J. H. Robison

Prepared in cooperation with
the Oregon State Water
Resources Board

OPEN-FILE REPORT
Portland, Oregon

fr U.S. GOVERNMENT PRINTING OFFICE: 1965-0-789-362

 ESTIMATED EXISTING AND POTENTIAL GROUND-WATER STORAGE
IN MAJOR DRAINAGE BASINS IN OREGON

CONTENTS
Page
Purposes and objectives -------------------------

1

General comments on basins ----------------------

1

Index map of Oregon showing drainage basins
and subdivisions ------------------------------

2

Explanation for table --------

9

Table:

-----------------

Estimated existing and potential
ground-water storage in major drainage
subdivisions in Oregon ------------------ At back

 ESTIMATED EXISTING AND POTENTIAL GROUND-WATER STORAGE IN MAJOR
DRAINAGE BASINS IN OREGON

By J. H. Robison

PURPOSES AND OBJECTIVES
Because of expected greater needs for water and for better environmental control, the Oregon State Water Resources Board and others
having an interest in water-resources development and management must
have knowledge of the volume of ground water in storage as well as of
the space available for additional storage underground. To provide these
estimates, the U.S. Geological Survey has analyzed existing geologic
and hydrologic data.
In estimating storage space available for ground water, little
consideration was given to the possible sources of recharge water.
Presumably some areas deficient in surface supplies would require water
available only by interbasin transfer.
GENERAL COMMENTS ON BASINS
1.

NORTH COAST:

This area is underlain mostly by marine sedimentary rocks and volcanic rocks of low porosity and permeability; consequently, winter runoff
is high, recharge to ground water is small, and streams are low during
the summer base-flow period. Ground-water withdrawals have been negligible, and the small yields of wells tend to restrict ground-water use
to individual house supplies.
Moderate to large quantities of water can be obtained from wells in
the dune lands. The high infiltration capacity of the sand allows precipitation to recharge large volumes of water into the dune-land groundwater reservoirs. Water tables in the dune areas could be raised or
lowered to adapt to seasonal use and recharge conditions.

 17.

SOUTH COAST:
Same comments as (1).

18.

MID COAST:
Same comments as (1).

2A.

UPPER WILIAMETTE:

The Coast Fork and Willamette (Long Tom) subdivisions are similar
to the coastal basins; they are underlain mostly by relatively impermeable rocks, and thus the streams have low base flows during the
summer. Except for areas underlain by thin alluvial deposits adjacent
to the Willamette River, ground-water withdrawals are small. Potential
for ground-water management is limited.
The McKenzie River and Middle Fork of the Willamette drain the high
part of the Cascade Range, which is underlain by porous permeable lava,
tuff, and ash that readily accept water. Precipitation is abundant,
but -most of it falls as snow in the winter. Because the snow melts
slowly in most years, infiltration capacity of the porous soils is
seldom exceeded, and direct runoff is small. A high percentage of the
total precipitation becomes ground-water recharge. The streams, which
receive most of their flow from discharge of ground water, have a high,
rather uniform base flow throughout the year.
Although the aquifers are permeable, ground-water resources have
not been developed, mainly because regional water levels are deep.
Reliable estimates of the average thicknesses of the saturated zones are
difficult to make because the average depth of the water table is unknown. The few existing wells commonly draw water from perched zones;
many of the lakes at high altitudes are perched above the regional water
table.
The potential for additional storage in the Cascade areas is substantial because of the permeable nature of the rocks and the deep
water levels. Artificial recharge might be practiced either by surface spreading or by injection through wells. An "on-call" recovery
of this water at the recharge site might be difficult or impractical
in some situations, but additional recharge would cause streamflow to
become more uniform throughout the year--an asset for production of
hydroelectric power, irrigation diversions, and other uses.
2B.

MIDDLE WILIAMETTE:

The Upper Santiam and Pudding subdivisions lie partly in the
Cascade Range. The same comments as made above about other Cascade
areas apply. Most of the Coast Range subdivision is similar to the
bedrock areas of the coastal basins.

 Natural recharge in the alluvial areas at the lower altitudes of
the basin is moderately high, and more water could be used for irrigation than is used at present. The water table beneath the valley
plains is generally too high to permit additional storage.
2C.

LOWER WILIAMETTE :

The hills and slopes of the Tualatin subdivision are underlain by
basalt, whereas the valleys are underlain by alluvial gravel, sand, and
silt. Recharge to alluvial aquifers is adequate to offset present and
foreseeable future withdrawals. Water levels in aquifers within the
basalt have declined near some sites of concentrated withdrawal, as at
Bull Mountain, Beaverton, and Tigard, which indicates that large withdrawals need to be adequately regulated.
Ground-water-management potential may be limited to relatively small
quantities of water. Additional withdrawals from the basalt aquifers
can be replaced by artificial recharge. The containment of additional
recharge water within the basalt of the hill areas would be limited because the unsaturated zones of the basalt lie in peaks and in rather
narrow ranges.
The higher parts of the Clackamas and Sandy subdivisions have characteristics typical of the western part of the Cascade Range, being
underlain by volcanic rocks of lower permeability and porosity than
those of the high parts of the Cascade Range.
The lower parts of the Clackamas and Sandy and the higher part of
the Columbia subdivision are underlain by young terrace sand and gravel,
older mudstone and conglomerate, and basalt. Depths to water range
from 50 to several hundred feet below land surface, and wells yield
small to moderate quantities of water. Additional water could be withdrawn, and there is some room for additional storage. Because of impaired vertical permeability and perched water, artificial recharge
would have to be limited to selected zones through use of injection
wells.
Artificial recharge is practiced in downtown Portland, in the sense
that ground water pumped from basalt and alluvial aquifers is used for
heating and air-conditioning systems and immediately returned to the
aquifers.
Lower parts of the Columbia subdivision, adjacent to the Columbia
River, are underlain by highly permeable gravel, and increased withdrawals of ground water would probably result in a corresponding increase in induced recharge from the streams.

 4.

HOOD:

Basalt is the principal aquifer in the Wasco subdivision. Yields
of water to wells are moderate to large, but tectonic structures in the
basalt have caused hydraulic compartmentation that restricts natural
recharge. The covering tuff deposit of the Dalles Formation also restricts recharge.
Ground water in the higher part of the Wasco area is only partly
developed, but in the vicinity of The Dalles, substantial pumpage has
caused a critical decline in water levels within one structural compartment. Parts of the subdivision could be recharged artificially,
with eventual benefit to the area. The declining ground-water reservoir at The Dalles could also be repressurized.
Young porous volcanic rocks of the Hood subdivision probably have
good potential for ground-water withdrawal, artificial recharge, and
storage of large volumes of water, although presently ground-water resources are almost untested except for the use of spring discharges.
Regional water levels lie deep beneath the higher parts of the area.
5.

DESCHUTES:

The Upper and Middle Deschutes subdivisions are underlain by rocks
of good infiltration capacity, permeability, and specific yield that
characterize the higher parts of the Cascade Range. Regional water
levels are deep, and large quantities of additional water could be
stored either by spreading or by point recharge of excess surface water.
6.

JOHN DAY:

Mountainous portions of the North Fork and Upper John Day subdivisions are underlain by basalt and older crystalline and metamorphic
rocks, but the basalt is commonly above the water table and overlies
rocks of low yield and permeability. Springs emanating from perched
zones are common, but additional storage of large quantities of water
appears" impractical in these rugged areas. A little additional water
might be recharged into the upper parts of alluvial fans lying at the
base of the mountains and also to some parts of the basalt.
Basalt in the Lower John Day is largely untested for water yields,
but should contain moderate quantities of recoverable ground water.
Precipitation is not so great as in the higher parts of the basin, but
small dams in the Upper and North Fork might capture excess runoff for
transport to artificial-recharge sites in the Lower John Day subdivision.

 7.

UMATILLA:

The Walla Walla subbasin is underlain by basalt and alluvium;
both are permeable enough to yield moderate to large quantities of
water to wells. The basalt aquifers are locally overdeveloped but can
be easily recharged. Shallow water levels and the relatively steep
slopes of the valley floors require that special techniques be used to
obtain additional storage in the alluvium.
The Willow Creek subdivision and the northwestern part of the
Umatilla subdivision are underlain by basalt aquifers in the upland to
the south. The lowland to the north is underlain by alluvial and
basaltic aquifers. Although precipitation is small, the alluvium appears
to be adequately recharged for present withdrawals for irrigation. However, because the basalt is compartmented, water levels are declining
rapidly near Ordnance and lower Butter Creek. If ground-water withdrawals are increased, similar declines in water levels in other areas
can be expected, but adequate artificial recharge could prevent or
nullify such declines
8.

GRANDE RONDE:

Parts of the Upper Grande Ronde and most of the Imnaha, Wallowa,
and Lower Grande Ronde subdivisions lie in mountainous, uninhabited
terrain. The area is underlain by igneous and metamorphic rocks of low
permeability and specific yield. These rocks may be poor aquifers even
for domestic needs. Where present and saturated, layered lavas yield
moderate to large quantities of water to wells.
Parts of the upper and middle subdivisions are underlain by
alluvium and lacustrine deposits and layered lavas that yield sufficient water for irrigation. Additional water might be put into upper
parts of alluvial fans, but this could cause waterlogging in the
valleys, where water levels in places are shallow.
9.

POWDER:

The Burnt River area is underlain mostly by pre-Tertiary rocks of
low specific yield. Basaltic rocks and sedimentary deposits of Tertiary
age are limited in extent and lie above the regional water table in
most places. The sedimentary deposits and the basalt might store a
part of the small discharge of this river valley.
Baker Valley, in the Powder River subdivision, contains extensive
and productive alluvial aquifers^ Additional storage would have to be
small and selective to prevent waterlogging of bottom lands. With the
exception of several small areas underlain by permeable alluvial
deposits or permeable lavas, the remaining parts of the Powder River
subdivision are underlain by poorly permeable metamorphic and crystalline rocks or by lacustrine deposits.

 10.

MALHEUR:

Large areas of the basin are underlain by pre-Tertiary metamorphic
rocks of low yield and permeability, but there are also some areas
underlain by permeable Tertiary lavas. Some valleys in the basin contain permeable alluvium; however, recharge to ground water is negligible
because precipitation is small, and therefore the aquifers are easily
overpumped.
Total water needs of the basin are greater than the resources, and
there is room for additional ground-water storage.
11.

OWYHEE:

The basin is underlain by lavas and other volcanic rocks of moderate to good permeability. Water levels are deep, and thus few wells
have been drilled.
Precipitation is small, but there is substantial storage space
available for artificially recharged ground water. All the runoff is
now used for irrigation.
12.

MALHEUR LAKE:

Basalt and pre-Tertiary rocks underlie the mountainous areas, and
alluvium, lacustrine deposits, and volcanic rocks underlie the low areas.
The basalt has low to moderate permeability and porosity. Some of the
sedimentary deposits have moderate permeability, and there are some finegrained deposits that yield small quantities of water of poor quality.
Precipitation is small in the lower areas and moderate but variable
in the areas of higher altitude.
There is good potential for additional storage in the basin; the
effective porosity factor is moderate, and water levels are deep in
many places. Aquifers are practically untested and unused but have
great potential in some subbasins, such as Bear Valley on the upper
Silvies River.
13.

GOOSE AND SUMMER LAKES:

The area comprises topographically closed basins underlain by
Tertiary to Recent basalt and other volcanic rocks, and alluvial deposits, all of good permeability and porosity. The basins lie in the
rain shadow of the Cascade Range; thus precipitation is low on the basin
floors but greater on the upper parts of the watersheds.

 Small to moderate yields can be obtained from wells in the alluvium, and moderate to large yields can be obtained from wells in the
basalt and pyroclastic rocks. Presently these aquifers are not overpumped. The basaltic rocks are receptive to natural recharge and could
serve as good reservoirs for imported water.

14.

KIAMATH:

The very porous, permeable volcanic rocks that are typical of the
high parts of the Cascade Range underlie much of the western half of
the basin. Permeable basalt, pumice, and andesite, and less permeable
sedimentary rocks underlie the eastern half of the basin.
Streamflow is largely discharge from ground water. Much of the
streamflow evaporates from large lakes or is used for irrigation.
Where the depth to water is not great, moderate to large quantities
of water are generally obtainable from wells drilled into volcanic
rocks.
The possibilities for artificial recharge and additional storage
are excellent in the western half of the basin and good in the eastern
half.
15.

ROGUE:

The higher part of the basin, which is drained by the main stem of
the Rogue River, is similar in geologic and hydrologic characteristics
to the western part of the Klamath Basin.
The lower part of the Rogue is underlain by early Tertiary tuff,
lava, and sedimentary rocks, and by pre-Tertiary igneous and sedimentary rocks, all of low porosity and permeability. These rocks yield
only small quantities of water to wells.
Even though precipitation is heavy, ground-water recharge is small,
except in the volcanic rocks of the high part of the Cascade Range and
in the sedimentary deposits beneath several small valley areas.
The rugged topography and the low permeability of the rocks
throughout most of the area restrict.the potential for ground-water
management and additional storage.
16.

UMPQUA:

The upper part of the North Umpqua subbasin is underlain by porous
volcanic rocks of the high part of the Cascade Range; this part has
geologic and hydrologic characteristics similar to the higher part of
the Rogue Basin. Ground-water outflow from this part of the basin
provides most of the base flow of the river system, and the area has
potential for artificially increased ground-water storage.
8

 The South and the Lower Umpqua subdivisions are underlain by
marine sedimentary and metamorphic rocks of low permeability. These
areas are similar to the coastal basin areas in that the generally
impermeable rocks largely preclude artificial increase of ground-water
storage.
EXPLANATION FOR TABLE
DRAINAGE BASINS AND SUBDIVISIONS:
The boundaries correspond in general to those on the map of the
Water Resources Board. Exceptions are the three coastal basins, whose
subdivisions are physiographic, and the Sandy River area, which is included as a subdivision of the Lower Willamette Basin rather than as a
separate basin. Where necessary, basins were further divided for this
report.
TOTAL AREA:
Areas, in square miles and acres, are those published by the
Water Resources Board or determined from U.S. Geological Survey data.
Only the parts of river basins actually within the State of Oregon are
included.
GROUND-WATER CONDITIONS:
Natural recharge.--These quantities are estimated. For coastal
areas, the average streamflow for the month of minimum flow (usually
September) multiplied by 12 gives conservative, though reasonable,
values for the annual discharge from ground water. This may be a reliable estimate of the annual ground-water recharge. For places where
evapotranspiration rates are higher than in coastal areas, the sum of
the flow of the 3 lowest months multiplied by four was used to obtain
values that seem reasonable. However, in the driest parts of the State,
where precipitation is low and evapotranspiration is excessive, this
method also gives values for annual ground-water recharge that seem too
low, even by conservative criteria.
If precise enough data were available, the following hydrologic
equation could be used:
GROUND-WATER RECHARGE = PRECIPITATION - EVAPOTRANSPIRATION - DIRECT
RUNOFF - SOIL UPTAKE
Runoff is commonly the only component of the equation known with satisfactory precision; values of precipitation obtained from isohyetal
maps are very much generalized; and evapotranspiration and soil uptake
must be estimated. The values of ground-water recharge can be in
error by a large percentage where the recharge is small relative to the
other components of the equation.

 Recharge figures in the table have been obtained largely by the
base-flow methods described above and probably represent conservative
or minimum values.
Artificial recharge.--These values are based on estimates and on
published figures. Because of lack of current data, values are subject
to adjustment. Many of the existing recharge operations are experimental and not continuous.
Ground-water withdrawals.--These values are based on published estimates, where available, or on assumed requirements for known industrial, municipal, domestic, and irrigation developments in each area.
Relative potential for additional withdrawals.--Qualitative estimates of potential for additional withdrawals of ground water were
related to present rates and foreseen increased demands.
H- Most or all parts of the area show potential for substantial
additional ground-water withdrawals
+ Most or all parts of the area show potential for additional
ground-water withdrawals
0 Overall ground-water withdrawals are near limit without
"mining"
- Substantial parts of the area are already developed beyond rate
of natural ground-water recharge.
Where two symbols are given, the first applies to the subdivision
as a whole, and the second applies to local but important areas that
differ from the average for the whole subdivision. Because an area
may be classified as underdeveloped does not necessarily mean that
yields to conventionally constructed individual wells are satisfactory
for all or even most purposes.
SATURATED ZONE:
Area of recoverable storage.--Where topographic relief is measured in thousands of feet and/or accessibility by road now is limited,
the area of practical recovery of ground water is assumed to be less
than the total area, at least for extensive use or management purposes. For present economic and technological conditions, the area of
potential recovery of ground water for some areas would be less than
is shown on the table.

10

 Effective porosity factor.--The effective porosity factor, expressed
in percentage of the thickness of the saturated zone, is used to determine the volume of water that would come out of or go into storage
when an unconfined regional water table is lowered or raised. The
effective-porosity-factor values are estimated composite averages of
short-term specific yields of all materials in the saturated zone. The
values are smaller than those for specific yield if drainage time were
infinite, and are used to compute the volume of manageable stored ground
water for a given area. For example, if a thousand-acre area has an
average depth to water of 100 feet and an average depth to the base of
the zone of recoverable water of 200 feet (thus a 100-foot-thick
saturated zone) and an effective porosity factor of 20 percent, the
volume of manageable storage in acre-feet would be computed:
.20 x 100 ft x 1,000 acres - 20,000 acre-ft.
Average depth to base of zone of recoverable water.--Figures in
the table apply to the depth of the zone below land surface.
Average thickness above 500 feet.--This is the thickness of saturated materials in the zone 0-500 feet below land surface. It is
dependent on the depth of the water table. Because water-table maps
are available for few areas and spot information may be sparse or lacking for some areas, water levels are probably the least accurate factor
used in computing saturated thicknesses and volumes. For example, a
little-known area that was estimated to have an average depth to water
of 300 feet would have a saturated thickness of 200 feet above a depth
of 500 feet. If the average depth to water were actually 400 feet instead of 300, the thickness would be 100 feet--an error of 100 percent.
Ground water above 500 feet.--This is the volume of ground water
in natural storage at a depth of less than 500 feet. The volume is
obtained by multiplying Area of Recoverable Storage times the Effective Porosity Factor times Average Thickness Above 500 Feet.
Ground water below 500 feet.--This is the volume of usable ground
water below a depth of 500 feet. It may be potentially recoverable.
It is obtained from estimates of area, thickness, and yield, and is
usually supported by inadequate data. The effective porosity factor
is generally assumed to be less than that of the zone above 500.feet
depth.

11

 POTENTIAL ADDITIONAL STORAGE:
Estimated area.--This is the area, in acres, where hydrologic,
geologic, and physiographic conditions indicate that the water table
can be raised substantially above its natural conditions. The term
does not apply to areas where recharge is used to restore water levels
already lowered by artificial depletions.
No additional storage has been estimated for most areas where high
precipitation is combined with shallow water levels; under natural conditions, these areas reject recharge during winter. More recharge
would waterlog them. In the coastal dune lands the benefits of raising
water levels artificially are presumed to outweigh any detrimental
effects of waterlogging.
Average thickness of zone.--It is the thickness, in feet, averaged over the Estimated Area of Potential Additional Storage.
Effective porosity factor.--It is the same as was defined under
Saturated Zone, except that it applies to unsaturated zones.
Volume of manageable storage.--The values are obtained by multiplying Estimated Area times Effective Porosity Factor times Average
Thickness.
PRINCIPAL AQUIFER TYPES:
This column of the table identifies aquifer materials that are
presently or potentially important. Because of such factors as different thicknesses of aquifers and/or the different specific yields
of the aquifers, adjacent subdivisions with similar aquifer types may
show dissimilar figures under Volume of Manageable Storage.

12

 I

5=

<» e
r* * e>
o
n e

r> V

s-o-yji-s

? = S7"i?
*2."t:?-,,

<t ** O.V

r«>-s>B«r-e:§
o »- >-^
»v

- SB

s

BJS^
&5S

n

w «» c S»
*--o r* H
»- n

r» -< 3

o» a: o> n > R
»
rt » »- C

gftgffi

5S-S
F 3-?

< O -O

t- o e «
o i *o n

s  j? 

lss:  iSSeSr;
"rlrs 2<<
§

El <» n O >

t» » c o J3
c cr k o
n C

??B
c Q »»

ff?--Sf'
*
"

»- 5- JB

« Jt 8
»* * e:

2?3 S

^jSl-S
? *""ol

3 _ I <2 n

E1 * t* at e o
ll*e jt-o m
E JL P

c*S
iT a r>

£

? £?-*
«'5« w

r*

r
*

us

S55-*
Z.Z«

S ? 8 S

'j-c*,
o ^T o o

s,s??s

MII53
ooo-p

* "3 S E? H

p1* er* at e H
o <ff *> £ v a

S 1"

5 5

ca
o
C

-I 9  

IslffP
Sfzg

5 S. k

oion **,8"
k o t-c

"*~o* i* 2C

»- K O.

C

cacanS
« IT » o

*" *** " *""

? i s"7si

IssiS r3&SP
g r 5P *i"^i

p. 8 5

^aWo* P
c o » n

»» » . *3
O, r" B >

** >V Q
it »- e o

** **

s&

«t

SS^? 55-3
^?*3 *!

O, *- 3 Q

w > O^B
HP c~

*** '** *""

O,

- 3

6a

3S"
^^a-

» >y
o>**c

 3

(See taMe)

OREGON DRAINAGE BASINS

Subdivisions
X*

Owyhcc
Ma 1 lieu r Lake,
Goose and Sutraner Lakes
Klamath
Rogue
Urr.pqua
South Coast
Mid Coast

Will ame tee
Upper Willamette
Middle Wiliamette
Lower Willamette
Hood
Deschutes
John Day
Umatilla
Grande Kond'e
Powder

North Coast

BASINS