REG1 ONAL GROUNDWATER POTENTIAL FOR

SUPPLYING IRRIGATION WATER: 1985

UNION BAY TO OYSTER RIVER

K.D. Ronneseth M i c i s t r y o f A g r i c u l t u r e and Food

A p r i l 1985

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TABLE OF CONTENTS

Page

TABLE OF CONTENTS ................................................ ii

L I S T OF F I G U R E S .................................................. iii

ACKNOWLEDGEMENTS ................................................. i v

1. I N T R O D U C T I O N ..................................................... 1

2. PHYSIOGRAPHY ..................................................... 2

3. BEDROCK GEOLOGY .................................................. 2

4. UNCONSOLIDATED D E P O S I T S .......................................... 2

5. GROUNDWATER P O T E N T I A L ............................................ 3

5.1 Bedrock ....................................................... 3

5.2 U n c o n s o l i d a t e d ................................................ 9

6. E X T E N T OF DEVELOPED AND P O T E N T I A L A Q U I F E R S ....................... 15

7. WATER Q U A L I T Y .................................................... 1 7

8. CONCLUSIONS ...................................................... 20

9. REFERENCES ....................................................... 21

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F i g u r e 1

F i g u r e 2

F i g u r e 3

F i g u r e 4

F i g u r e 5

F i g u r e 6

F i g u r e 7

F i g u r e 8

F i g u r e 9

F i g u r e 10

F i g u r e 11

F i g u r e 12

F i g u r e 13

F i g u r e 14

LIST OF FIGURES

Page

Regional Groundwater P o t e n t i a l f o r Supply ing I n s i d e o f I r r i g a t i o n Water 92F.065 ........................ Back Cover

Regional Groundwater P o t e n t i a l f o r Supply ing I n s i d e o f I r r i g a t i o n Water 92F.066 ........................ Back Cover

Regional Groundwater P o t e n t i a1 f o r Supply ing I n s i d e o f I r r i g a t i o n Water 92F.075 ........................ Back Cover

Regional Groundwater P o t e n t i a l f o r Supp ly ing I n s i d e o f I r r i g a t i o n Water 92F.076 ........................ Back Cover,

Regional Groundwater P o t e n t i a l f o r Supp ly ing I n s i d e of I r r i g a t i o n Water 92F.084 ........................ Back Cover

Regional Groundwater P o t e n t i a l f o r Supp ly ing I n s i d e o f I r r i g a t i o n Water 92F.085 ........................ Back Cover

C l ima t i c -Geo log ic Un i ts , S t r a t i g r a p h y and La te P1 e i s tocene Envi ronments o f t h e Study Area ....... 4

Geologic Cross-Sect ion (Sandwick Area) ........... 5

Geologic Cross-Sect ion (Grantham-Merv i l le Area) .. 6

Fence Diagram (Area n o r t h of Comox) .............. 7

Fence Diagram (between Comox Lake and Courtenay) .................................... 8

I n f e r r e d D i s t r i b u t i o n o f Quadra Sand and Cowichan Head Format ion .......................... 12

A Contour Map o f t h e H y d r a u l i c Head i n Water Wel ls Completed i n a Conf ined A q u i f e r .................. 13

Water Wel ls Where E i t h e r a S a l t y o r Petroleum Taste t o t h e Water was Reported .................. 19

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AC KN 0 W L ED GEM EN TS

The author wishes t o acknowledge t h e support , t h e use o f groundwater

d a t a and t h e t e c h n i c a l ass is tance prov ided by t h e s t a f f o f t h e Groundwater

Sect i o n o f t h e Water Management Branch , M i n i s t r y of Envi ronment . Speci a1

thanks t o t h e s t a f f o f t h e Coal I n v e n t o r y Sect ion o f t h e Geologica l Branch,

M i n i s t r y o f Energy, Mines and Petroleum Resources f o r t h e i r suppor t and t h e

use o f g e o l o g i c a l data.

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1. INTRODUCTION

The M i n i s t r y o f A g r i c u l t u r e and Food i n c o n j u n c t i o n w i t h t h e / A g r i c u l t u r a l Land Commission a r e i n v o l v e d i n a d e t a i l e d assessment o f t h e

a g r i c u l t u r a l c a p a b i l i t y o f t h e east coast of Vancouver I s l a n d . An a n a l y s i s

o f t h e h y d r o l o g i c a l data was i d e n t i f i e d as an impor tan t requirement i n t h e

above assessment w i t h groundwater be ing a major component.

Th is r e p o r t , accompanying maps, c ross-sec t ions and fence diagrams

p r o v i d e s a d i s c u s s i o n and a n a l y s i s o f developed and p o t e n t i a l a q u i f e r s , f o r

t h e areas between Union Bay and Oyster R i v e r , based on p r e s e n t l y a v a i l a b l e

groundwater and g e o l o g i c data. The map sheets which cover t h e study area

i n c l u d e 92F.065, 066, 075, 076, 084 and 085 (1:20,000 sca le ) . These map

sheets a r e i d e n t i f i e d as F i g u r e s 1, 2, 3, 4, 5 and 6.

The hydrogeo log ica l in fo rmat ion , t h e m a t i c a l l y presented on t h e map

sheets, c ross-sec t ions and fence diagrams a r e based on t h e t a b u l a t e d data

from 1250 water w e l l records, water w e l l l o c a t i o n maps ( b o t h on f i l e w i t h

t h e Groundwater Sect ion, M i n i s t r y o f Environment) , p u b l i s h e d s u r f i c i a l

geology maps and r e p o r t s ( F y l e s , 1963; M u l l e r and Atch ison, 1971) , t e r r a i n

maps ( M i n i s t r y o f Environment, B r i t i s h Columbia) and s o i l maps and r e p o r t s

( M i n i s t r y o f A g r i c u l t u r e and Food, B r i t i s h Columbia).

Tabulated data f rom water w e l l records (e.g., a q u i f e r c h a r a c t e r i s t i c s ,

depth t o bedrock, etc.) and coal e x p l o r a t i o n t e s t ho les (depth t o bedrock,

t h i c k n e s s o f overburden, e tc . ) were t r a n s f e r r e d t o water w e l l l o c a t i o n maps

( s c a l e 1:20,000) which were used as a working base. S u r f i c i a l geology/-

t e r r a i n u n i t s and g l a c i a l f e a t u r e s (e.g., d e l t a kames) which were considered

hydrogeo log ica l l y s i g n i f i c a n t i n terms o f groundwater p o t e n t i a l were t r a n s f e r r e d t o these same maps. A syn thes is o f t h i s da ta was then

t r a n s f e r r e d t o t h e f i n a l 1:20,000 sca le base maps.

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2. PHYSIOGRAPHY

The two major nor thwest - t rend ing geomorphic f e a t u r e s o f t h e study area

a r e t h e r e s u l t of s t r u c t u r a l , e r o s i o n a l and d e p o s i t i o n a l processes. These

f e a t u r e s a r e t h e eas tern face o f t h e Vancouver I s l a n d Ranges o f t h e I n s u l a r

Mountain Phys iographic D i v i s i o n w i t h e l e v a t i o n s t o 750 metres and an

u n d u l a t i n g coas ta l lowland o f t h e Coastal Trough Physiographic D i v i s i o n ,

r i s i n g f rom sea l e v e l t o approx imate ly 200 metres and rang ing from 10 t o 19 k i l o m e t e r s i n width.

3. BEDROCK GEOLOGY

Accord ing t o M u l l e r (1977), Vancouver I s l a n d i s t h e main component o f

t h e I n s u l a r B e l t , t h e westernmost major t e c t o n i c s u b d i v i s i o n o f t h e Canadian C o r d i l l e r a . The study area conta ins Paleozoic rocks ( a l imestone f o r m a t i o n

o f t h e S i c k e r Group), Lower Mesozoic rocks ( a v o l c a n i c f o r m a t i o n o f t h e

Vancouver Group) and Upper Mesozoic rocks ( c o n s i s t i n g o f c y c l i c a l upward

f i n i n g sequences o f conglomerate, sandstone, sha le and coal o f non-marine o r

near d e l t a i c o r i g i n , suceeded by mar ine sandstone, sha le o r t h i n bedded and

graded s h a l e - s i l t s t o n e sequences f rom t h e Nanaimo Group) and Cenozoic rocks

( s m a l l p l u t o n s and s i l l s o f t h e Sooke I n t r u s i o n s ) . The coas ta l lowlands a r e

p r i n c i p a l l y under1 a i n by t h e Nanaimo Group.

4. UNCONSOLIDATED DEPOSI TS

Most o f t h e unconso l ida ted m a t e r i a l s found i n t h e study area may be

a t t r i b u t e d t o t h e regimen and wast ing o f g l a c i a l i c e d u r i n g t h e L a t e

Ple is tocene. Though some o f t h e unconsol idated d e p o s i t s a re t h e r e s u l t o f

o l d e r g l a c i a l (Dashwood D r i f t ) and i n t e r g l a c i a l (Mapleguard and Cowichan

Head Sediments) a c t i v i t y , t h e m a j o r i t y o f t h e depos i ted sediments a re f rom

t h e Fraser G l a c i a t i o n . The Fraser G l a c i a t i o n probably represents t h e same

g e o l o g i c - c l i m a t i c t i m e p e r i o d as t h e C l a s s i c a l L a t e Wisconsin G l a c i a t i o n o f

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t h e mid-cont inent r e g i o n ( A l l e y and Chatwin, 1979). Fy les (1963) has mapped

t h e s u r f i c i a l unconso l ida ted sediments w i t h i n t h e study area a t a s c a l e o f

1 : 63,360.

A s t r a t i g r a p h i c framework o f unconso l ida ted sediments and a chronology

o f L a t e P l e i s t o c e n e environments i n t h e study area, i s shown i n F i g u r e 7.

The t h i c k n e s s and v e r t i c a l v a r i a t i o n o f t h e unconso l ida ted sediments w i t h i n

t h e study area i s shown by c ross s e c t i o n s i n F igures 8 and 9 and i n t h e

fence diagrams i n F i g u r e s 10 and 11.

5 . GROUNDWATER POTEN TI AL

5.1 Bedrock

Groundwater w i t h i n t h e bedrock can be found i n f r a c t u r e s , a long

bedding p lane p a r t i n g s , i n t h e i n t e r - f l o w zones o f lava, i n t h e i n t e r -

g r a n u l a r openings i n t h e rock, and i n t h e case o f l imestone, i n t h e

channels formed by t h e d i s s o l u t i o n o f t h e rock by water. Water w e l l s

d r i l l e d on Vancouver I s l a n d , i n d i c a t e f r a c t u r e s , bedding p lane p a r t i n g s

and s o l u t i o n channels a r e probably t h e main sources o f groundwater f rom

t h e bedrock. A l l bedrock w e l l s i n t h e study area appear t o be completed

i n rocks o f t h e Nanaimo Group, p r i n c i p a l l y shales and sandstones. The

r a p i d accumulat ion o f sediments which make up these rocks, accounts f o r

t h e i r be ing p o o r l y sor ted, massive and, i n general , l a c k i n g i n pore spaces

and condu i ts f o r t h e t r a n s m i s s i o n of water (Ha ls tead and T r e i c h e l , 1966).

Water we1 1 s d r i l l e d i n these sediments i n d i c a t e f r a c t u r e s and bedding

p l a n e p a r t i n g s a r e t h e main sources o f groundwater. Water w e l l s completed

i n sandstone g e n e r a l l y r e p o r t e d h i g h e r y i e l d s than we1 1s completed i n

shales. F i v e w e l l s were observed t o be completed i n sandstones versus

t w e n t y - s i x w e l l s completed i n shales.

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YEARS BEFORE PRESENT

(kt t o k a l e )

Present I

5,000 .

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CLIMATIC IN11

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M A C I ATION

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OLYMPIA

INTERNAL WON-GLACIAL

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PUYALLUP NON-GLACIAL INTERVAL

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GEOLOGIC WITS

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STRATIGRAPHY

Gravel, rand. s i l t , clay. peat; a l l u v i a l fan h P 0 S l t S ; blodrs and rubble; peat and luck

Gravel, sand and si1 t y forming Ice-contx deltas Grey till, sand 0 clayey texture

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lay. stony clay, s i l t containing mrine hells, loca l basal 1aminated clay and Ilt

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and. s i l t , minor clay and gravel

Figure 7. CLIMATIC GEOLOGIC UNITS. STRATIGRAPHY AND LATE PLEISTOCENE ENVIRONIIENTS ff THE S N D Y AREA a f t e r Clague (1981. 1977 6 1976) Al ley 1 Chatwin (1979). Armstrong e t a1 11965) 6 Halstead 11966)

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SCALE - 0 5000

met res I 1 I I I b

GEOLOGIC SECTION

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x 7 x 7 Y 7 " , X 7 19 !l; Y 7 x 7

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Predominantly Sand and/ or Grave 1 500 1000 1500

metres

j Vertical exaggeration i s I approximately 25 times

> I e.*e-***.* = Water Table . 1 X6 Y10 21 = Water Well

I Figure 8

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GEOLOGIC

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LEGEND

C D = Location of Cross Sec t ion

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30

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Sea Level.

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CROSS SECTION

X 4 Y11 18 Y11 23

24

LEGEND AND SCALE F

Predominantly Sand and/or Grave 1 500 1000 1500

metres

Verti cal exagge ra t i on i s approximate1.y 25 times

X6 Y10 21 = Water Well

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FENCE

Y HORIZONTAL SCALE IN METRES

0 300 600 900 1.2oc PREDOMINANTLY TILL & J

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PREOWINANTLY SAND VERTICAL

20 IN

DIAGRAM

I INDEX PLAN LEGEND

A X10E-Y5-19 A UATER WELL ON FILE jYITH THE GROUNDWATER

BRANliH. MINISTRY OF SECTION. UATER MNAGMENT

ENVII)ONHENT. I ' I

HORIZONTAL SCALE

?J ! * , , , * 3m

METRES -

figure 10

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FENCE 1 DIAGRAM

O J

C 146 = A coal exploratioa testhole 5 file

w i t h the Gmlogic Branch of the -try of

Energy, Wries and Petrulean Resources.

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The p o s s i b i l i t y o f o b t a i n i n g adequate supp l ies o f groundwater f o r i r r i -

g a t i o n purposes from these sources a r e g e n e r a l l y cons idered t o be poor and

a l though a few bedrock w e l l s i n t h e study area have been r e p o r t e d t o y i e l d

between 1 and 5 L/s ( f i v e l i t r e s p e r second i s s i g n i f i c a n t when

c o n s i d e r i n g i r r i g a t i o n requi rements) , l o n g d u r a t i o n pumping t e s t s would be

r e q u i r e d t o v e r i f y i f bedrock a q u i f e r s a re capable o f a sus ta ined h i g h

wi thdrawal ra te. A bedrock a q u i f e r w i t h p o t e n t i a l e x i s t s i n t h e M i r a c l e

Beach park area (map sheet 92F.085). E x i s t i n g data r e v e a l s a sandstone

f o r m a t i o n where f o u r w e l l s show repor ted y i e l d s g r e a t e r than 1 L/s and one

w e l l g r e a t e r t h a n 5 L/s.

Examples o f bedrock a q u i f e r s capable o f y i e l d i n g s u f f i c i e n t s u p p l i e s o f groundwater f o r i r r i g a t i o n purposes can be found i n t h e M i l l Bay and

Saanich reg ions o f southern Vancouver I s l a n d where w e l l y i e l d s up t o

16 L/s have been obtained. It i s no t known i f comparable h i g h y i e l d i n g

bedrock a q u i f e r s e x i s t i n t h e study area. To i d e n t i f y such a q u i f e r s would

r e q u i r e d e t a i l e d g e o l o g i c mapping, a e r i a l photograph a n a l y s i s , and

p o s s i b l y geophysica l i n v e s t i g a t i o n s , as w e l l as t e s t d r i l l i n g . These

procedures can be bo th time-consuming and expensive.

5.2 Unconsol idated Deposi ts

Most of t h e groundwater used on Vancouver I s l a n d comes from unconso l i -

dated d e p o s i t s which r e c e i v e water f rom i n f i l t r a t i o n o f e i t h e r p r e c i p i t a -

t i o n o r s u r f a c e water sources. The amount o f water o b t a i n a b l e from these

m a t e r i a l s , depends on t h e p e r m e a b i l i t y o f t h e a q u i f e r m a t e r i a l , t h e t h i c k -

ness and e x t e n t o f t h e a q u i f e r , t h e r a t e o f a q u i f e r recharge and on w e l l

c o n s t r u c t i o n .

The unconso l ida ted d e p o s i t s which are hydrogeo log ica l l y s i g n i f i c a n t i n

terms o f groundwater p o t e n t i a l f o r i r r i g a t i o n purposes a r e p r i m a r i l y

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comprised o f sand and/or gravel . The depos i ts which f a l l i n t o t h i s

category a re l i s t e d and discussed below:

1) The shore, d e l t a i c , f l u v i a l and a l l u v i a l d e p o s i t s o f t h e S a l i s h

Sediments. These depos i ts range up t o 10 ' metres i n th ickness .

Thickness o f any sand and/or g rave l depos i ts 0.5 metres o r g r e a t e r a r e

considered s i g n i f i c a n t i n terms o f groundwater p o t e n t i a l . The pr imary

t a r g e t f o r groundwater e x p l o r a t i o n would be t h e f l u v i a l d e p o s i t s near

p r e s e n t day stream channels and de l tas . These would i n c l u d e t h e

v a l l e y s and/or d e l t a s o f t h e Oyster, Tsolum, Trend and L i t t l e Rivers.

2 ) Terraced f l u v i a l depos i ts which i n c l u d e d e l t a i c , channel, f l o o d p l a i n

and a l l u v i a l f a n d e p o s i t s a long w i t h some marine and/or g lac io -mar ine

d e p o s i t s o f t h e Capi lano Sediments. These d e p o s i t s a re s i g n i f i c a n t l y

h i g h e r o r lower (approx. 6 met res) than t h e present l e v e l s o f s i m i l a r

p r e s e n t day d e p o s i t s (Fy les , 1963). These d e p o s i t s range up t o

20 metres i n t h i c k n e s s and 2000 metres across. The d e l t a i c t e r r a c e s

would be pr imary t a r g e t areas f o r groundwater e x p l o r a t i o n . Examples

o f t e r r a c e d f l u v i a l d e p o s i t s can be found a long t h e Oyster, Brown,

Punt ledge and Trend R i v e r Val leys. Minor t e r r a c e d f l u v i a l depos i ts

occur along t h e Tsolum r i v e r , Dove Creek and j u s t west by southwest o f

Cumber1 and.

3 ) The g l a c i o f l u v i a l depos i ts which i n c l u d e hummocky, knob and k e t t l e ,

r i d g e d , esker, t e r r a c e and p i t t e d t e r r a c e , kame t e r r a c e , kame d e l t a

and i c e c o n t a c t a l l u v i a l fan d e p o s i t s o f t h e Vashon Drift. These

d e p o s i t s a r e found r e s t i n g upon t h e ground moraine o f t h e Vashon

D r i f t . Usua l ly l o c a t e d w i t h i n a couple o f m i l e s o f t h e mountain

s lopes, these d e p o s i t s may range up t o 2 k i l o m e t e r s wide and 7 k i l o m e t e r s long. One such depos i t e x i s t s a t t h e o u t l e t of Comox Lake

and l o c a l l y may exceed 5 0 metres i n th ickness. The fence diagram i n

F i g u r e I 1 g r a p h i c a l l y p o r t r a y s t h i s sand and grave l deposi t . It i s

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probab le t h a t a major a q u i f e r e x i s t s w i t h i n t h i s kame deposi t . The

kame t e r r a c e s and kame d e l t a s would be pr imary t a r g e t areas f o r

groundwater e x p l o r a t i o n . Another area of g l a c i o - f l u v i a l d e p o s i t s can

be found where t h e Oyster R i v e r leaves t h e I n s u l a r Mountains.

Lenses of sand and/or g rave l a re assoc ia ted w i t h t h e ground moraine

d e p o s i t s o f t h e Vashon D r i f t . Though these lenses a r e p o t e n t i a l

a q u i f e r s t h e i r l o c a t i o n and v i a b i l i t y must be conf i rmed by d r i l l i n g ,

which can be bo th expensive and t i m e consuming.

4) The g l a c i o f l u v i a l depos i ts o f t h e Quadra Sediments (Fy les , 1963) known

as t h e Quadra Sand (Clague, 1977). The groundwater p o t e n t i a l o f t h i s

g e o l o g i c u n i t m e r i t s an expanded understanding o f i t s d i s t r i b u t i o n and

o r i g i n .

Quadra Sand i s found throughout much o f t h e southern p o r t i o n o f t h e

s tudy area, u s u a l l y below t h e 100 met re e l e v a t i o n l e v e l . Comprised

predominant ly o f sand w i t h minor s i l t and grave l these d e p o s i t s

l o c a l l y exceed 75 metres i n th ickness. Water w e l l l o g s have r e p o r t e d

g r e a t e r than 20 metres o f sand which p o s s i b l y be long t o t h e Quadra

Sand U n i t . O v e r l a i n by g l a c i a l sediments (ma in ly t i l l ) o f t h e Fraser

G l a c i a t i o n and u n d e r l a i n by sediments o f t h e Olympia I n t e r g l a c i a l

i n t e r v a l t h e c u r r e n t theory on t h e o r i g i n o f Quadra Sand i s summarized

by C1 ague ( 1977) be l ow:

"The sand was deposi ted, i n p a r t , as d i s t a l outwash aprons

a t success ive p o s i t i o n s i n f r o n t o f and perhaps a long t h e

marg ins o f g l a c i e r s moving from t h e Coast Mountains i n t o t h e

Georgia Depression and Puget Low1 and d u r i n g L a t e Wisconsin

t ime. A f t e r d e p o s i t i o n a t a s i t e , b u t b e f o r e b u r i a l by i c e ,

t h e sand was d i s s e c t e d by mel twater and t h e eroded d e t r i t u s

. .

Ir I I I I I I 1 I I I I I 1 I I I 1 I

- 12 -

was t ranspor ted f a r t h e r down the basin t o sites where aggradat ion con t i nued. "

An extensive d e p o s i t of Q u a d r a Sand i s b e l i e v e d t o e x i s t i n a 4 t o 6 k i lome te r wide bel t from the southern part of the Comox Peninsula no r th to the Oyster River area. The inferred d i s t r i b u t i o n of Quadra Sand i s shown i n Figure 12. The lower po r t ions of the c ross - sec t ion shown i n F i g u r e 8 i l l u s t r a t e s sand and/or gravel units which probably represent the Quadra Sand. The fence diagram i n F igure 10 shows an ex tens ive lower u n i t comprised predominantly of sand which a1 so probably represents the Quadra Sand U n i t . T h i s fence diagram g raph ica l ly por t rays an ex tens ive confined aquifer a t this loca t ion . F igure 13 i s a contour mp of the hydraul ic head of water we1 1 s completed i n the above-mentioned confined aquifer. The hydraul ic head o r water level e l e v a t i o n s ( i n mtres above sea leve l 1 provides a map which i n d i c a t e s d i r e c t i o n s 'of groundwater flow and an a rea o f recharge. T h i s type of information is necessary t o quant i fy ground- water q u a n t i t i e s and to solve problems of water qua l i ty . The extensive- ness of the Quadra Sand, its thickness and l o c a l l y proven yields of 6 L/s makes this depos i t a primary t a r g e t f o r groundwater exp lo ra t ion .

Figure 12.

Inferred distribution of Quadra Sand and Cmichan Head Foxmation (after Clague, 1977).

- 13- ..

FIGURE 13 : A contour map of the hydraulic head i n w a t e r weld; m p l e t d i n a confined aquifer. The

aquifer is probably in aadra Sand . The hydraulic head or water I sea level) provides a map which indicates directions of grouJhter - 1

I ' level elevations ( i n metres above

flow i n the aquifer.

- 14 -

5 ) A g r a v e l and sand depos i t found beneath g l a c i a l d r i f t o f t h e Fraser

G l a c i a t i o n b u t whose r e l a t i o n s h i p t o Quadra Sand i s unknown. Deposi ts

o f t h i s u n i t found south o f t h e study area a r e r e p o r t e d (Fy les, 1963)

t o be 75 metres i n th ickness. The on ly known exposures o f t h i s u n i t

t o be found w i t h i n t h e study area are l o c a t e d i n t h e Oyster R i v e r

Va l ley . The extens iveness o f t h i s u n i t i s unknown and though t h e r e i s

a l a c k o f groundwater data f o r t h i s geo log ic u n i t , t h e composi t ion

makes i t a t a r g e t area f o r groundwater e x p l o r a t i o n .

The f o l l o w i n g i s a summary o f groundwater data f rom water w e l l records

i n t h e study areas. Many o f t h e w e l l s were completed i n one o r more o f t h e

d e p o s i t s j u s t descr ibed.

Over 470 water we1 1 records show t h i c k n e s s o f unconso l ida ted m a t e r i a l s

r a n g i n g from 1 t o 110 metres and averaging 30 metres. One hundred and

twenty coal e x p l o r a t i o n t e s t h o l e s show t h i c k n e s s o f unconso l ida ted m a t e r i a l ,

r a n g i n g from 0 t o 5 0 metres and averaging 10 metres. The water w e l l s were g e n e r a l l y l o c a t e d i n t h e lowlands where t h e unconso l ida ted sediments were

t h i c k e r .

Over 440 water w e l l records which showed w e l l s completed i n sand and/or

g r a v e l , ranged i n depth f rom 1 t o 76 metres and averaged 30 metres. The

apparent depth t o t h e t o p o f a sand and/or g rave l a q u i f e r , based on over 440

water w e l l records ranged f rom 1 t o 84 metres w i t h 26 be ing t h e average.

Over 440 water w e l l records showed apparent a q u i f e r th icknesses ranging

f rom 0.3 t o 30 metres w i t h about 5 metres be ing t h e average. Water w e l l

records show w e l l y i e l d s a r e r e p o r t e d t o range from l e s s than 0.1 L/s t o

g r e a t e r than 44 L/s. Wells completed i n bedrock r e p o r t e d average y i e l d s o f

i I B I

- 15 -

0.5 L/s and w e l l s completed i n sand and/or g rave l r e p o r t e d average y i e l d s o f

1.4 L/s. E ighteen w e l l s completed i n sand and/or g rave l r e p o r t e d y i e l d s

g r e a t e r than 6 L/s. F i v e l i t r e s per second i s s i g n i f i c a n t when c o n s i d e r i n g

i r r i g a t i o n requirements.

A v a i l a b l e da ta f rom o t h e r hydrogeo log ica l s t u d i e s show s p r i n g s

r e p o r t i n g a f l o w r a t e up t o 12 L/s ( s o u t h o f Courtenay) and w e l l s capable o f

y i e l d i n g g r e a t e r than 40 ,L/s (Oyster R i v e r area). The few 24 hour pump

t e s t s a v a i l a b l e on f i l e w i t h t h e Groundwater Sec t ion showed s p e c i f i c

c a p a c i t y r a t i n g s up t o 74 L/s/metre o f drawdown. These r a t i n g s a r e s i g n i -

f i c a n t i n terms o f groundwater p o t e n t i a l .

The f o l l o w i n g i s a d e s c r i p t i o n and t h e l i m i t a t i o n s o f each component

shown on t h e 1:20,000 s c a l e base maps.

6. EXTENT OF DEVELOPED AND POTENTIAL AOUIFERS

AREA A: Area A o u t l i n e s t h e s u r f i c i a l e x t e n t o f

unconso l ida ted d e p o s i t s p r i m a r i l y comprised o f

sand and/or g rave l s. Area A ou t1 i n e s areas where

t h e r e i s a h i g h p r o b a b i l i t y o f l o c a t i n g water-

b e a r i n g sand and/or g rave l a q u i f e r s b u t does n o t imp ly t h e e x i s t e n c e o f water-bear ing sand and/or

g r a v e l a q u i f e r s . In 'some areas f o r example t h e sand and grave l depos i ts may be very t h i n and dry throughout t h e i r e n t i r e th ickness .

Area A o u t l i n e s p o t e n t i a l unconf ined a q u i f e r s a t sur face, i t does n o t show

d i s t r i b u t i o n a t depth. This i s e s p e c i a l l y r e l e v a n t t o t h e Quadra Sand and

p o s s i b l y t o some p r e - F r a s e r G l a c i a t i o n u n c o n s o l i d a t e d s e d i m e n t s

(e.g., Mapleguard sediments) which may under1 i e younger depos i ts (mar ine

c l a y s f o r example) i n t h e region.

.I l:I I I II I I I I I I I I I

I I I I

~'

++ ++ +++ ++ ++ ++ +++- ++++++++++++++++-

L + + + + + + + + + + + + + + + + -

+++++++++++++++++- I++++++++++++++++: ++++++++++++++++ I::::::::::::::::: !++++++++++++++++.

- 16 -

AREA B: Area B o u t l i n e s reg ions where sand

and/or g rave l a q u i f e r s ( g r e a t e r than 0.5 metres

i n t h i c k n e s s ) have been i d e n t i f i e d a t depth based

on water we1 1 1 i t h o l o g y records. These a q u i f e r s

may be e i t h e r c o n f i n e d o r unconfined. F i g u r e 10 g r a p h i c a l l y shows water we1 1s cons t ruc ted i n a

--

The s u r f i c i a l geology u n i t s which make up Area A were t r a n s f e r r e d f i r s t from

1:63,360 s c a l e mapping t o 1:12,000 s c a l e water w e l l l o c a t i o n maps, and then

t o 1:20,000 s c a l e c a d a s t r a l maps. Minor boundary e r r o r s may e x i s t t h e r e f o r e

on t h e l a r g e r s c a l e mapping.

The boundar ies o f Area B were a r b i t r a r i l y s e t a t a 100 met re r a d i u s f rom a

d a t a p o i n t (water w e l l ) which i d e n t i f i e d a sand and/or g rave l a q u i f e r

g r e a t e r than 0.5 metres i n th ickness. Where two w e l l s , l o c a t e d w i t h i n 400

metres o f each o ther , show s i m i l a r l i t h o l o g i e s and t h e geomorphology o f t h e

area was homogeneous, Area B was extended between t h e two we l ls .

AREA C : Area C o u t l i n e s a r e a s where t h e

unconso l ida ted d e p o s i t s a t sur face (predominant ly

t i l l s , s i l t s a n d / o r c l a y s ) a r e g e n e r a l l y

u n s u i t a b l e as a q u i f e r m a t e r i a l s due t o t h e i r low

p e r r n e a b i l i t y . However, s u i t a b l e a q u i f e r

m a t e r i a l s may and do e x i s t a t depth as evidenced

i n many reg ions o f Area C where s i t e s p e c i f i c data a r e a v a i l a b l e . The

fence diagram i n F i g u r e 10 g r a p h i c a l l y d i s p l a y s t h i s s i t u a t i o n . Where

ground moraine d e p o s i t s have been mapped i n Area C, l o c a l l y t h e r e may be

sand and/or g rave l depos i ts found a t sur face o r i n lenses a t depth. Also,

o l d e r geo log ic u n i t s (e.g., Quadra Sand) t h a t a re s i g n i f i c a n t a q u i f e r s may

be o v e r l a i n by t h e marine and moraine d e p o s i t s found i n Area C. Produc t ive

a q u i f e r s may be found i n these o l d e r geo log ic u n i t s .

- 17 -

The boundar ies o f Area C were a l s o t r a n s f e r r e d from F y l e s (1963) s u r f i c i a l

geology maps (1:63,360 s c a l e ) . Minor boundary e r r o r s t h e r e f o r e may e x i s t on

t h e 1 arger s c a l e mapping.

AREA D: Area D was i d e n t i f i e d where bedrock i s

l o c a t e d a t o r near ground s u r f a c e and/or where

w e l l l o g s i n d i c a t e b e d r o c k a q u i f e r s . The

boundar ies f o r Area D were a l s o a r b i t r a r i l y s e t

a t 100 metre r a d i u s f rom a da ta p o i n t (e.g.,

bedrock w e l l o r rock outcrop) . This d i s t a n c e was

extended t o 400 metres between data p o i n t s i f water w e l l l i t h o l o g y and t h e

s u r f a c e morpho1 ogy so warranted.

A

A

Water w e l l s where y i e l d s g r e a t e r than 3 L/s have

been repor ted. Where these w e l l s a r e found i n

Area B these areas show t h e h i g h e s t p o t e n t i a l f o r

o b t a i n i n g groundwater s u p p l i e s t o meet i r r i g a t i o n

r e q u i rements.

Water w e l l s where y i e l d s between 1 and 3 L/s a r e

repor ted. These areas a l s o show h i g h p o t e n t i a l

f o r o b t a i n i n g i r r i g a t i o n s u p p l i e s of ground-

water.

7. WATER QUAL1 TY

The c o n c e n t r a t i o n and composi t ion o f d i s s o l v e d c o n s t i t u e n t s i n a water

determine i t s q u a l i t y f o r i r r i g a t i o n use. Three o f t h e c h a r a c t e r i s t i c s o f

an i r r i g a t i o n water t h a t appear t o be t h e most impor tan t i n de termin ing i t s

q u a l i t y a r e t h e t o t a l concent ra t ions o f s o l u b l e s a l t s , t h e r e l a t i v e propor-

t i o n o f sodium t o o t h e r c a t i o n s and t h e concent ra t ions o f boron and o t h e r

elements t h a t may be t o x i c .

- 18 -

The t o t a l c o n c e n t r a t i o n of s o l u b l e s a l t s can be expressed i n terms o f

i t s e l e c t r i c a l c o n d u c t i v i t y and i s measured i n micromhos/cm a t 25OC. The

h i g h e r t h e c o n c e n t r a t i o n o f s o l u b l e s a l t s and m i n e r a l s t h e h i g h e r t h e

c o n d u c t i v i t y . The e l e c t r i c a l c o n d u c t i v i t y o f 5 o f t h e 6 l a b o r a t o r y analyses

o f groundwaters from unconsol idated a q u i f e r s ranged f rom 14 t o 112

m i cromhos/cm. These waters a r e i n t h e low s a l i n i t y hazard c l a s s

(Richards, 1969). According t o Richards (1969), these waters can be used

f o r i r r i g a t i o n w i t h most crops w i t h l i t t l e l i k e l i h o o d t h a t s o i l s a l i n i t y

w i 1 1 devel op.

A s a l t y t a s t e i n t h e groundwater was recorded on 12 water w e l l records The d i s t r i b u t i o n of these w e l l s can be seen i n F i g u r e 14. This i m p l i e s a

h i g h c h l o r i d e read ing of g r e a t e r than 300 mg/L (Anderson, 1973). Though

t h i s read ing may or may n o t i n d i c a t e a h i g h l e v e l o f t o t a l d i s s o l v e d s o l i d s ,

t h e sodium a b s o p r t i o n r a t i o i s l i k e l y t o be high. A l l o f these 12 w e l l s

were completed i n shale. A pet ro leum t a s t e o f unknown source was a l s o

r e p o r t e d i n t h e water from two we l ls . Water q u a l i t y analyses would be

r e q u i r e d t o v e r i f y comments on s a l t y o r pet ro leum t a s t i n g groundwaters and

i f so, t o determine i f these groundwaters a re w i t h i n acceptable l i m i t s f o r

i r r i g a t i o n use.

The r e l a t i v e p r o p o r t i o n o f sodium t o o t h e r c a t i o n s ( u s u a l l y ca lc ium and

magnesium) i n groundwaters may make some waters undes i rab le f o r some crops.

T h i s r e l a t i o n s h i p i s u s u a l l y expressed as t h e sodium a b s o r p t i o n r a t i o (SAR)

where SAR = Na+/ J(Ca+' + Mg+')/2 and can be used f o r i d e n t i f y i n g t h e s u i t -

a b i l i t y o f groundwaters f o r i r r i g a t i o n purposes. The fo rmula a p p l i e s where

a l l concent ra t ions a r e expressed i n epm. Apply ing t h e SAR formula t o f o u r

l a b o r a t o r y analyses revea led t h e sodium hazard l e v e l as be ing low t o very

l o w f rom t h e groundwaters o f these unconso l ida ted a q u i f e r s . Bedrock a q u i f e r s , however, may c o n t a i n h i g h e r l e v e l s o f sodium r e l a t i v e t o ca lc ium

and magnesium as was t h e case r e p o r t e d i n one coas ta l bedrock w e l l south o f

t h e study area.

'I I I I I I I I

- 19 -

f l I

L 3 - l o

/ N

-

?jrdmau n Z;.LIU>

LEGEND

o Location o f wells reporting sa l t water

eLocatlon o f wells reportlng a petroleum taste to the water

4-26 - water t e l l l o a t i o n nuther Gmmiwater Section, W a t e r EIanagarent B r w h , B.C.)

0 5 10 '7 Ki lometers Kllometers

Figure 14. Water wells where e i t h e r a s a l t y o r petroleum taste to the water w a s reported.

- 20 -

1 1 I I I I

I I I

Another impor tan t c h a r a c t e r i s t i c of i r r i g a t i o n waters a r e concentra-

t i o n s of boron and o t h e r elements t h a t may be t o x i c . The one l a b analyses

which t e s t e d f o r boron was w i t h i n acceptable l i m i t s ( < 0 . 3 3 mg/L). Based on

f o u r low Tota l D i s s o l v e d S o l i d s readings, i t i s probable t h a t t o x i c elements

found i n most groundwaters f rom unconsol idated a q u i f e r s w i l l be w i t h i n

acceptab le l i m i t s . High l e v e l s o f Boron (2.68 mg/L), however, have been

found i n t h e Cretaceous bedrock i n o t h e r p a r t s o f Vancouver I s l a n d . I t i s

n o t known i f h i g h l e v e l s o f t o x i c elements a r e present i n t h e study area,

e s p e c i a l l y i n t h e bedrock groundwaters.

More analyses ( f rom we1 1 s compl e ted i n bo th unconsol i d a t e d m a t e r i a1 s

and bedrock) would p r o v i d e a more complete understanding o f n a t u r a l water q u a l i t y w i t h i n t h e study area.

8. CONCLUSIONS

On a r e g i o n a l bas is , t h e r e i s a h i g h p o t e n t i a l f o r l o c a t ng groundwater

s u p p l i e s capable o f meet ing i r r i g a t i o n requirements i n t h e coas ta l p l a i n

r e g i o n o f t h e study area. The l a r g e s t groundwater reserves n t h e area a r e conta ined i n r e c e n t a l l u v i a l depos i ts , t e r r a c e d f l u v i a l and d e l t a i c

depos i ts , and i n t h e Quadra Sand and o t h e r sediments beneath t h e Vashon

Drift.

Though t h e r e i s a p a u c i t y o f w e l l l o g i n f o r m a t i o n a v a i l a b l e f o r much o f

t h e study area, s u i t a b l e geo log ic d e p o s i t s i n d i c a t e t h e p o t e n t i a l

a v a i l a b i l i t y o f groundwater f o r i r r i g a t i o n purposes. Even where water we1 1

l o g i n f o r m a t i o n i s a v a i l a b l e , most water w e l l l o g s r e p o r t e d y i e l d s f rom sand

and/or g rave l a q u i f e r s a t l e s s than 2 L/s. This i s u s u a l l y t h e r e s u l t o f

t h e immediate needs o f t h e water user. A s i n g l e f a m i l y home on ly r e q u i r e s a

w e l l y i e l d o f 0.2 L/s. A more e f f i c i e n t development of t h e same a q u i f e r

w i l l o f t e n y i e l d h i g h e r p r o d u c t i v i t y .

I I1 I I I I I I I I JI I I I I I I I I

- 21 -

N a t u r a l water q u a l i t y i s expected t o be acceptable f rom t h e ground-

waters o f unconso l ida ted deposi ts . Not enough da ta i s a v a i l a b l e on t h e

water q u a l i t y o f bedrock a q u i f e r s b u t comments f rom a dozen water w e l l l o g s

i n d i c a t e t h e need f o r more water q u a l i t y . One area o f concern i s man

induced p o l l u t i o n t o groundwater. A number o f l a n d f i l l s i t e s a r e l o c a t e d i n

t h e s e same sand and/or g rave l depos i ts which c o n t a i n p r o d u c t i v e a q u i f e r s ,

Groundwater w i thdrawals f rom these areas should always be analysed f o r t o x i c

elements such as heavy metals.

Th is r e p o r t i s r e g i o n a l i n scope and i d e n t i f i e s areas which have t h e

p o t e n t i a l t o supply i r r i g a t i o n water. It does no t p r o v i d e a q u a n t i t a t i v e

assessment o f water a v a i l a b i l i t y f o r a s i t e s p e c i f i c l o c a t i o n . To p r o v i d e

such an assessment, more accura te d e l i n e a t i o n o f a q u i f e r boundar ies and e s t i m a t i o n o f groundwater recharge, movement, a q u i f e r parameters and w i t h -

drawal would be r e q u i r e d on a s i t e s p e c i f i c basis.

9. REFERENCES

A l l e y , N.F. and Chatwin, S.C. 1979. La te P l e i s t o c e n e H i s t o r y and

Geomorphology , Southwestern Vancouver I s l a n d , B r i t i s h Columbia.

Canadian Journa l of E a r t h Sciences, Vol. 16, No. 9, pp. 1645-1657.

Anderson, K.E. 1973. Water Well Handbook, Missour i Water Well & Pump

C o n t r a c t o r s Assoc ia t ion , Inc . S c h o l i n Bros. P r i n t i n g Co., S t . Louis,

Montana, U.S.A., 281 p.

Armstrong, J.E., Crande l l , D.R., Easterbrook, D,J. and Noble, J.B. 1965.

L a t e P l e i s t o c e n e S t r a t i g r a p h y and Chronology i n Southwestern B r i t i s h

Columbia and Nor thwestern Washington. Geologica l Soc ie ty o f Pmerica,

B u l l e t i n , Vol. 76, pp. 321-330.

I, I I I I I I I I I I I I D I I I I I

- 22 -

Clague, J.J. 1976. Quadra Sands and i t s R e l a t i o n t o t h e L a t e Wisconsin

G l a c i a t i o n of Southwestern B r i t i s h Columbia. Geologica l Survey o f

Canada, Canadian Journal o f Ear th Sciences, Vol. 13, pp. 803-815.

Clague, 5.3. 1977. Quadra Sands: A Study o f t h e L a t e P l e i s t o c e n e Geology

and Geomorphic H i s t o r y o f Coastal Southwest B r i t i s h Columbia.

Geologica l Survey of Canada, Paper 77-17, O t t a w a , 24 p.

Clague, J.J. 1981. Late Quaternary Geology and Geochronology o f B r i t i s h

Columbia. P a r t 2: Summary and D iscuss ion o f Radiocarbon-Dated

Quaternary H i s t o r y . Geologica l Survey o f Canada, Paper 80-35, Ottawa,

41 p.

Fy les, J.G. 1963. S u r f i c i a l Geology o f Horne Lake and P a r k s v i l l e Map

Areas, Vancouver I s l a n d , B r i t i s h Columbia, 92 F/7, 92 F/8. Geologica l

Survey o f Canada, Memoir 318, Ottawa, 142 p.

Halstead, E.C. 1966. S u r f i c i a l Geology o f Duncan and Shawnigan Map Areas,

B.C. Geo log ica l Survey o f Canada, Paper 65-24, 3 p.

Halstead, E.C. and Trechel, A. 1966. Groundwater Resources o f t h e Coastal

Lowland and Adjacent I s l a n d s . Nanoose Bay t o Campbell R iver , East

Coast Vancouver I s l a n d . Geologica l Survey o f Canada, B u l l e t i n 144.

M u l l e r , J.E. and Atch ison, M.E. 1971. Geology, H i s t o r y and P o t e n t i a l o f Vancouver I s l a n d Coal Deposi ts. Geologica l Survey o f Canada,

Paper 70-53, 5 0 p.

M u l l e r , J.E. 1977. Geology o f Vancouver I s l a n d , Marg ina l Notes. 3

sheets. Open F i l e r e p o r t 463, Geologica l Survey o f Canada.

Richards, L.A. ( E d i t o r ) . 1969. Diagnosis and Improvement o f S a l i n e and

A l k a l i S o i l s . U n i t e d Sta tes S a l i n i t y Laboratory S t a f f , A g r i c u l t u r a l

Handbook No. 60, U n i t e d Sta tes Department o f A g r i c u l t u r e , Washington,

160 p.

4

MINISTRY OF ENVIRONMENT W a t e r Mana g e m e n t B r a n c h

Regional Groundwater Potent ial for Supplying I r r igat ion Water

A cell n i t h a reported estimated field 3f greater than 3 litres oer second.

A Well with 3 reoo:ted ?st-rnated +lei$ 3f Cetneer a n 0 3 . - t z e s zer sec~n3.

(D (0 0

IP -a

/ ,imit 2f surficial jeology mapping. Qonnesetn, M a y 1985 .

368000

i I

+ 4 5504000

,o c

0 190

00000 + 1 + MINISTRY OF ENVIRONMENT Water Management Branch

Regionail Groundwater Potent ial for Supplying irr igat ion Water

A r e a s d h e r e sana 3nd23r ; r a v e l 3 a u i f e r s n a v e b e e v i a e i r . i F L e 2 a t d e s t - . 3 a s e o 3n aell i l t h o l o c y . ' - ese : q u i f e r s f a y o e e i t h e r c o n f i n e 2 o r a n c o n t i l e a .

d e l l w i t h a i e o o r r e d e s t - m a t e d " i e l d s f 3 e t w e e - . 3n0 3 i . t r e ~ z e r sezcnc l . d e l l a i t h a r e c o r t e d e s t i m a t e d , i e l d 3 f A q r e a t e r t h a r 3 l i t r e 5 p e r s e c o n o . A

q o n n e s e t h , May11985 / - : T i t ,f s u r f i c i a l q e o i o g y q a p p i n g .

72HN059 A

2 . 1

531.12 105 A

2 . 1

5496000

I ! 49'36' 00" I

368000 124' 48 ' 00"

I SEE INDEX 92F PROJECT No. 81-023P-C ) . - I P L A N I M E T R I C NEG. NO. 214917

- E : 1:ZOOO 200 400 600

NTERVRL HETRES L

0

i

5

0 ,

+

MINISTRY OF ENVIRONMENT Water Manag erne n t Branch

Regional Groundwater Potential for Supplying lrrigatilon Water

Areas w h e r e s a n d a n d / o r g r a v e l a q u i f e r s f e r s ( p r e d o m i n a n t l y s a n d s a n d g r a v e l s ) h a v e b e e n i d e n t i f i e d a t d e p t h b a s e d o n b a s e d on s u r f i c i a l g e o l o g y maps ( F y l e s , we l l l i t h o l i o g y . T h e s e a q u i f e r s may be

e i t h e r c o n f i n e d o r u n c o n f i n e d .

P o t e n t i a l u n c o n s o l i d a t e d u n c o n f i n e d a q u i -

L

i n d i c a t e b e d r o c k a q u i f e r s .

A Well w i t h a r e p o r t e d e s t i m a t e d y i e l d o f g r e a t e r t h a n 3 l i t r e s p e r s e c o n d . A Well w i t h a r e p o r t e d e s t i m a t e d y i e l d of

b e t w e e n 1 a n d 3 l i t r e s p e r s e c o n d .

B l k . 1 2 2 3 / L i m i t o f s u r f i c i a l g e o l o g y m a p p i n g . R o n n e s e t h , May/1985

'i > r

\ I - t B l k . 1340

..

.O -u

MT BROOKS

R R O V 1 NC STRATA O N A MTN b

- i

48

55 1

- 25' ' 00

600C

-.. 49' de''

19" 4 8 * 0 0 "

5 16000

=r r r

L

n T>

ID r 0

L P J a

12000

I I

MJNISTRY OF ENVIRONMENT Water Manage me n t Bran c h

Regional Groundwater Potential for Supplying Irr igation Water

idated unconfined auul- y sands ana gravels) geology maps SFyles, nav oe

I; 1. :A either confined or unconfiqed. . . . . . . .

lidated ts ana

-:nW- 5 mav

incons ills, si 3wi fers mater l a

- _ _ _ . indicate bedrock aquifers.

well with a reported estimated viela 2 , greater than 3 lltres per second. A

/ Limit o r sutficial geology mapplng.

dell with a reported est oetreen 1 and 3 litres P A mated V

r second eld o f

aonneseth, May/1985

/-

__ .. .

47' i 49" 42' 0O"t

125" 12 '00 " Y 2 F .OF5 . _...

P R b E D - G R R V E L ROUGH --

-+--I- Pi fWER i ;NE ON POLE _+_ ON 'OLIER ---(xt-

125" 00"- - -

SCALE : 1:20000 PLANIMETRIC SEE INDEX 92F , PROJECT No. 81-023P-C I 200 o zoo 400 600 8on N E G . NO. 214910

92F 0075 tlETRES I CADASTRAL I3 I C I TAI METRES CONTOUR I N T E R V A L

36802.

K I T T Y COLEMAN BEACH PARK

55 i 60df

5

c

t

MI N I STR Y OF E NV 11 R 0 N M E MT Water Management Branch

~ ~~~~~

Regional Groundwater Potential for Supplying Irr igation Water

Areas where sand and/or gravel aquifers have been identified at d e o t h oased on well lithology. These aquifers nav oe either confined or unconfined.

Potential unconsolidated unconfined aqui- o o o o o ~ o o ~ o ~ o fers (predominantlv sands and gravels) 0.: o o ~ ~ ~ o . , "

based 3n surficial geology maps i F y l e s , O 0 1963).

- - - - .L - Areas wnere :he surficial Anconsolidated - - ---I- - - - - deposits ipredomi?antlv tills, silts and - - - - - - clays) are unsuitaole a s aaulfers. H O W - 1-7 - - - I o - - - I - I ever, ~ ~ 1 s t at suitaole depth. aquifer materials mav

- - - - - _ - - - -

Areas where the possibility of obtaining adequate supplies of grounowater for ir- rigatizn ourooses are poor. 'hese are areas rrnere DedrOCK 1 s locate0 at or near ;round sdrface and/or uhere Hell l o g s indicate bedroclc aquifers.

dell nith a reported estimated yield of greater rhan 3 iitres per second. A

/ -imit sf surficial geology mapping.

a Well with a reported estimated vield of between 1 and 3 litres per second.

Ronneseth, May/1985.

L. 4

t

.

.

--

e L

--

az

-- I- --.. - c

n7c

125 49" 54' 01

55280C

552400n

L

MINISTRY OF ENVIRONMENT Water Manag e men t Branch

Regional Groundwater Potent ia l for Suppfying Irrigation Water

- W I NCE TISH

-

Potential unconsolidated unconfined aqui sands and gravels

geology maps (Fyles

Areas. where sand and/or gravel aquifers have been identified at depth based on vel1 lithology. These aquifers may be either confined or unconfined.

Areas where the surficial unconsolidated deposits (predominently tills, silts and clays) are unsuitable as aquifers. ever, suitable aquifer materials may HOW-

exist at depth.

Areas where the possibility of obtainin adequate supplies of groundnater for ir- rigation purposes are poor. These are areas where Wdroek is located at or near ground surface andror where well logs indicate bedrock aquifers.

well with a reported estimated yield of A greater then 3 litres per second. A between 1 and 3 litres per second. well with a reported estimated yield of

/ Limit of surficial geology mappilog. Ronneseth, Hay/1985.

.UWBICI

- e o - -

I" - No. - 8 -

- 81- - 4 -

'3

,/' - -

E

I

MINISTRY OF ENVIRONMENT Water Management Branch -

Regional Groundwater Potent ia l for Supplying Irr igat ion Water

i

5528221' -+

Areas where s a n d a n d / o r g r a v e l a q u l f e r s n a v e b e e n i d e n t i f i e d a t d e p t h b a s e d a n *ell l i t + i o l o g y . These a q u i f e r s may De e i t h e r c o n f i n e d o r u n c o n r l n e a .

P o t e n t l a l f e r s ( p r e d o m i n a n t l y J n c o n s o l l d a t e d s a n d s u n c o n f i n e d a n a g r a V e l S ) a q u i -

b a s e d on s u r f i c l a l g e o l o g y maps i F y l e s , 1 9 6 3 ) .

A r e a s w h e r e t h e o o s s i b i l r t y o f 3 b t a i n i n g a r e a s where t h e s u r f i c l a l ~ n c o n s o l l a a t e d g e D O S i t s ( p r e d o m i n a n t l v t i l l s , s i l t s a n a

- - - - - - 1 c l a y s ) a r e u n s u l t a o l e a s a q u l f e r s . +ion- 2 x l S t e v e r , a t s u i t a o l e d e p t h . a q u i f e r m a t e r l a i s mav

'''-;Yi?': a d e q u a t e s u p p i l e s o f g r o u n d w a t e r f o r l r - - , , # ; I $ , :,;,- r i g a t l o n p u r p o s e s a r e p o o r . These a r e -,.:,-8j:;'-,;: a r e a s where D e a r o c r i s l o c a t e d a t o r n e a r

g r o u n d s u r f a c e a n d / o r where well logs i n d i c a t e b'edrOCk a q u i f e r s .

- <<*.I'>'.t ,I,-/ I

i d e l l n i t h a r e p o r t e d e s t i m a t e d f i e l d 1 o f g r e a t e r Ehan 3 l i t r e s p e r s e c o n d . A

/ L i m i t o f s u r f i c i a i g e o l o g y mapp ing .

A d e l l w i t h a r e p o r t e d e s t i m a t e d v i e l d o f b e t w e e n 1 a n d 3 l i t r e s Der s e c o n d .

9 R o n n e s e t h , ~ a y / 1 9 8 5 .

+ 5 5 2 4 0 0 0 -+

BEACH

-+- - 5 5 2 0 0 0 0

5

4 8 - 49" - OF

:OLu PROVINCE BRlllSH

, 1-49" 48' 2C" 25" 30' 0 0 "

' - C PROJECT No. 81-023P

92F m085 c . ' .,

- 1