Long term trends in water quality, Haw and New Hope Rivers

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LONG TERM TRENDS I N WATER QUALITY LOWER HAW

AND

NEW HOPE RIVERS 1966-1973

by

C h a r l e s M. Weiss

Department of E n v i r o n m e n t a l S c i e n c e s and E n g i n e e r i n g S c h o o l o f P u b l i c H e a l t h

U n i v e r s i t y o f N o r t h C a r o l i n a a t C h a p e l H i l l

The work upon which t h i s p u b l i c a t i o n i s b a s e d was s u p p o r t e d i n p a r t by f u n d s p r o v i d e d by t h e O f f i c e o f Water R e s e a r c h and T e c h n o l o g y , Department o f t h e I n t e r i o r , t h r o u g h t h e Water R e s o u r c e s R e s e a r c h I n s t i t u t e of N o r t h C a r o l i n a a s a u t h o r i z e d u n d e r t h e Water R e s o u r c e s R e s e a r c h Act o f 1 9 6 4 . A d d i t i o n a l s u p p o r t was p r o v i d e d by c o n t r a c t s w i t h t h e C o r p s of E n g i n e e r s

,

Wilmington D i s t r i c t .

P r o j e c t No. Matching G r a n t B-007-NC Agreement No. 14-01-0001-1933

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A b s t r a c t

A s e v e n - y e a r r i v e r s a m p l i n g s e r i e s of t h e l o w e r Haw and New Hope R i v e r s , N o r t h C a r o l i n a , d e s i g n e d t o e s t a b l i s h t h e i r w a t e r q u a l i t y p r o f i l e s , h a s shown a l e v e l of q u a l i t y g e n e r a l l y a s s o c i a t e d w i t h s u b s t a n t i a l p o l l u t i o n l o a d s . However, i n t h e main s t e m o f t h e Haw a t a p o i n t a t t h e head o f t h e a r m o f t h e proposed B . E v e r e t t J o r d a n Lake (New Hope L a k e ) , oxygen a n d BOD5 q u a n t i t i e s i n d i c a t e t h a t s t a b i l i z a t i o n o f oxygen-demanding m a t e r i a l s and n i t r i f i c a t i o n o f n i t r o g e n o u s s u b s t a n c e s h a v e o c c u r r e d . The t o t a l p h o s p h o r u s c o n c e n t r a t i o n i n

t h e Haw R i v e r i s s e v e r a l t i m e s t h a t o f c o n t r o l s t r e a m s of t h e a r e a and t h e t o t a l l o a d o f t r a n s p o r t e d p h o s p h o r u s ( l b s / d a $ ) i s a p p r o x i m a t e l y f i v e times t h a t o f t h e New Hope R i v e r .

Sharp c h a n g e s i n s e v e r a l w a t e r q u a l i t y p a r a m e t e r s w e r e e v i d e n t i n a comparison o f t h e p e r i o d p r i o r t o 1 9 7 0 and a f t e r 1 9 7 0 . T h e s e c h a n g e s h a v e b e e n i d e n t i f i e d w i t h a n o v e r a l l c h a n g e i n r i v e r r u n o f f i n t h e r e g i o n , r e s u l t i n g from a s h i f t i n t h e p a t t e r n o f d r y t o wet y e a r s . The c h a n g e i n w a t e r q u a l i t y c a u s e d by v a r i a t i o n i n a v e r a g e r u n o f f was s u b s t a n t i a l enough t o mask a n y c h a n g e s t h a t may h a v e o c c u r r e d from v a r i a t i o n s i n q u a n t i t y of p o l l u t i n g s u b s t a n c e s

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P r e f a c e and Acknowledgements

The f i r s t w a t e r samples t a k e n f o r q u a l i t y a n a l y s i s from t h e New Hope and Haw R i v e r s , i n t h e e a r l y 6 0 1 s , were a s s o c i a t e d w i t h f i e l d e x e r c i s e s of a c l a s s i n limnology and w a t e r p o l l u t i o n t a u g h t by t h e a u t h o r . F o l l o w i n g c o n g r e s s i o n a l a u t h o r i z a t i o n of t h e New Hope P r o j e c t , P u b l i c Law 88-253 t h e 8 0 t h Congress December 30, 1963, t h r o u g h a s e r i e s of p r o j e c t s s u p p o r t e d by f u n d s d e r i v e d from s e v e r a l s o u r c e s as n o t e d below, a s y s t e m a t i c program of sampling was i n i t i a t e d i n t h e summer of 1966. Many of t h e p r o j e c t s p r o v i d e d m u t u a l and i n t e r a c t i n g s u p p o r t f o r t h e c o n t i n u a n c e of t h e sampling s e r i e s t h a t had been s t a r t e d . A s

t h i s u n i q u e sampling s e r i e s l e n g t h e n e d , t h e s i g n i f i c a n c e of m a i n t a i n i n g i t s

c o n t i n u i t y i n c r e a s e d a n d , a s w i l l b e s e e n from t h e r e s u l t s , i t i s c l e a r t h a t t h e r e a r e no s h o r t c u t s t o t h e d e t e r m i n a t i o n of changes t h a t r e f l e c t new l e v e l s of q u a l i t y .

C o n t r i b u t i n g P r o j e c t s

Water Resources Research I n s t i t u t e Pro j e c t No. B-003-NC

Matching Grant No. 14-01-0001-1037 Pro j e c t No

.

B-007 -NC

Matching Grant No. 14-01-0001-1933 P r o j e c t No. A-056-NC

Annual A l l o t m e n t No. 14-31-0001-3533

North C a r o l i n a Board of S c i e n c e and Technology Grant No. 104

Corps of E n g i n e e r s , Wilmington D i s t r i c t

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d a t a a s of November 1, 1966, and c o n t i n u i n g t h r o u g h October 31, 1973, many

s t a f f , t e c h n i c i a n s and s t u d e n t g r a d u a t e a s s i s t a n t s p a r t i c i p a t e d i n t h e

c o l l e c t i o n and a n a l y s i s of t h e d a t a . S e v e r a l a s s o c i a t e d p r o j e c t s were c a r r i e d

o u t d u r i n g t h e s e r i e s and have a l r e a d y been r e p o r t e d . No one p e r s o n e x c e p t f o r

t h e a u t h o r h a s remained w i t h t h e p r o j e c t t h r o u g h o u t i t s e n t i r e l e n g t h . S p e c i f i c

acknowledgements have been made i n e a r l i e r r e p o r t s c o v e r i n g v a r i o u s a s p e c t s of

c o l l a t e r a l i n v e s t i g a t i o n s . I n t h e p r e p a r a t i o n of t h e f i g u r e s and t a b l e s f o r

t h i s long-term a n a l y s i s , t h e a s s i s t a n c e of M s . Ann S c o t t and S a l l y Simpson

i s

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T a b l e of C o n t e n t s

Page

.

. . .

A b s t r a c t ii

. . .

P r e f a c e and Acknowledgements iii

. . .

L i s t of F i g u r e s a n d T a b l e s v i

. . .

Summary. C o n c l u s i o n s and Recommendations v i i

. . .

I n t r o d u c t i o n 1

. . .

Sampling and A n a l y t i c a l Methods 4

. . .

Data P r e s e n t a t i o n and Data A n a l y s i s 9

. . .

R e s u l t s 1 2

. . .

Changes i n R i v e r Flow 1 3

Water Q u a l i t y Changes a s a Consequence of Change i n R i v e r Flow

. .

1 9

. . .

Loading 20

. . .

Water Q u a l i t y - L a t e r a l Streams Lower Haw River 22

. . . .

Comparison of C o n t r o l Stream Q u a l i t y and Main R i v e r Q u a l i t y 29

. . .

Comparative Q u a l i t y of New Hope Headwater Streams 33

. . .

R e f e r e n c e s 36

. . .

G l o s s a r y 38

. . .

Appendix I

.

Seasonal Averages ( F i g u r e s ) 40

. . .

Haw R i v e r S t a t i o n s

.

Parameter C o n c e n t r a t i o n s 40

. . .

.

Haw R i v e r S t a t i o n s 5 and 6 Loading 60. 65

. . .

New Hope S t a t i o n s

.

Parameter C o n c e n t r a t i o n s 8 6

. . .

New Hope S t a t i o n 10

.

Loading 122

. . .

.

Appendix I1 Long-Term Averages ( T a b l e s ) 123

. . .

Haw R i v e r S t a t i o n s 1-5

.

Parameter C o n c e n t r a t i o n s 124

. . .

Haw R i v e r S t a t i o n 5

.

Loading 139

. . .

.

New Hope S t a t i o n s Parameter C o n c e n t r a t i o n s 1 4 1

. . .

New Hope S t a t i o n 1 0

.

Loading 168

. . .

Appendix I11

.

Three Year Seasonal Averages ( T a b l e s ) 170

. . .

.

Haw R i v e r S t a t i o n 6 Parameter C o n c e n t r a t i o n s 1 7 1

. . .

.

Haw R i v e r S t a t i o n 6 Loading 174

. . .

Haw R i v e r C o n t r o l S t a t i o n s ( L a t e r a l Streams) 7-12 176

. . .

.

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L i s t o f F i g u r e a n d T a b l e s

P a g e F i g u r e Area Map Showing L o c a t i o n s of Water Q u a l i t y Sampling

S t a t i o n s on t h e Haw a n d New Hope R i v e r D r a i n a g e s

. . .

3

T a b l e 1

T a b l e 2 T a b l e 3

T a b l e 4

T a b l e 5

T a b l e 6

T a b l e 7

T a b l e 8

T a b l e 9

T a b l e 1 0

T a b l e 11

T a b l e 1 2

T a b l e 1 3

T a b l e 14

Water Q u a l i t y Sampling L o c a t i o n s , New Hope and

. . .

Haw R i v e r s 6

P e r i o d s of Sampling Used i n Data A n a l y s i s

. . .

7

Water Q u a l i t y P a r a m e t e r s Determined i n t h e 1966-73

Sampling S e r i e s , Lower Haw and New Hope R i v e r s

. . .

8

A p p a r e n t Marked S h i f t s i n Q u a n t i t y of S p e c i f i c P a r a m e t e r s P r e and P o s t A p r i l - O c t o b e r 1 9 7 0 , a s

Noted o n F i g u r e s of Appendix I

. . .

1 4

Average R i v e r Flow a t S t a t i o n NH-10 f o r Monthly

Sequences Used i n Water Q u a l i t y A n a l y s i s

. . .

1 6 Average R i v e r Flow a t S t a t i o n Haw-5 f o r Monthly

S e q u e n c e s Used i n Water Q u a l i t y A n a l y s i s

. . .

1 7

Average Flow ( c f s ) f o r I n d i c a t e d P e r i o d s and P e r c e n t

Change, S t a t i o n s NH-10 and Haw

5 . . . , . . .

1 8 P e r c e n t Change i n Mean V a l u e s , L o a d i n g , NH-10 and Haw

5 . . .

2 1

. . .

Monthly Averaged Flow, S t a t i o n Haw-6 24

S e a s o n a l A v e r a g e s of Water Q u a l i t y P a r a m e t e r s f o r T h r e e C o n s e c u t i v e Y e a r s (Nov. 1970-Oct. 1 9 7 3 ) Lower Haw R i v e r

-

L a t e r a l S t r e a m s and R i v e r S t a t i o n Haw-5

. . .

2 5 Haw C o n t r o l S t a t i o n s , Mean S e a s o n a l V a l u e s of Water Q u a l i t y

. . .

P a r a m e t e r s , Haw R i v e r L a t e r a l ( C o n t r o l ) S t r e a m s 3 0 F r e q u e n c y With Which Any of Twenty S e a s o n a l l y Averaged

Water Q u a l i t y P a r a m e t e r s Showed Maximum D e v i a t i o n f r o m

Mean V a l u e o f A l l S t a t i o n s

. . .

3 1 P e r c e n t ( I n c r e a s e o r D e c r e a s e ) o f R i v e r Q u a l i t y f r o m

Mean o f C o n t r o l S t r e a m s i n Comparable Sampling P e r i o d s ,

1970-1973 . . .

C o m p a r a t i v e Q u a l i t y of New Hope Headwater S t r e a m s ,

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Summary, C o n c l u s i o n s and Recommendations

Water q u a l i t y c h a r a c t e r i s t i c s of t h e l o w e r Haw and New Hope R i v e r s , f o r t h e p e r i o d November 1966-October 1 9 7 3 , a r e d e s c r i b e d by a p r o f i l e o f 20 w a t e r q u a l i t y p a r a m e t e r s . D a t a c o l l e c t i o n was s y s t e m a t i c a l l y e x e c u t e d a t a

n e t w o r k o f s t a t i o n s o n t h e main s t e m r i v e r and t h e i r t r i b u t a r i e s . Both o f t h e s e r i v e r s r e c e i v e p o i n t s o u r c e d i s c h a r g e s of p o l l u t i o n m a t e r i a l s , g e n e r a l l y from w a s t e w a t e r t r e a t m e n t p l a n t s and i n d u s t r i a l d i s c h a r g e s . N o n - p o l l u t e d s t r e a m s f l o w i n g i n t o t h e main r i v e r s w e r e a l s o sampled t o c h a r a c t e r i z e t h e q u a l i t y of t h e n a t u r a l r u n o f f of t h e r e g i o n .

D a t a a n a l y s i s o f a l l p a r a m e t e r s began w i t h t h e p r e m i s e t h a t v a r i a t i o n s i n q u a l i t y h a v e a d i s t i n c t s e a s o n a l c h a r a c t e r . Thus, t h r o u g h e a c h a n n u a l c y c l e a l l s a m p l e s were s e p a r a t e d i n t o two s e a s o n a l s e t s : a w i n t e r s e r i e s , t h o s e

c o l l e c t e d f r o m November 1-March 3 1 , and a summer s e r i e s from A p r i l 1-October 3 1 . Throughout t h e p e r i o d o f t h i s r e p o r t , 1966-1973, a l l w a t e r q u a l i t y d a t a h a s b e e n summarized i n t h e s e s e a s o n a l s e g m e n t s . T h i s s e a s o n a l d i v i s i o n i n c l u d e s t h e i m p o r t a n t v a r i a b l e of r i v e r f l o w a s gauged a t t h r e e l o c a t i o n s w i t h i n t h e d r a i n a g e a r e a s t u d i e d .

A s h a r p c h a n g e i n t h e t r e n d i n w a t e r q u a l i t y was o b s e r v e d a t s e v e r a l

s t a t i o n s when pre-1970 d a t a was compared t o post-1970 d a t a . I n most i n s t a n c e s , t h e c h a n g e was a d e c r e a s e i n q u a n t i t y of s p e c i f i c p a r a m e t e r s . For

n o n c o n s e r v a t i v e s u b s t a n c e s , t h i s c o u l d i m p l y improvement i n w a t e r q u a l i t y . However, t h e same t r e n d was a l s o n o t e d f o r c o n s e r v a t i v e s u b s t a n c e s , and f u r t h e r a n a l y s i s r e l a t e d t h i s t o a marked c h a n g e i n r u n o f f . The l a t t e r r e s u l t e d i n a n

i n c r e a s e i n r i v e r f l o w of 80-100% b a s e d o n monthly a v e r a g e s i n t h e s e a s o n a l s e g m e n t s . I n some i n s t a n c e s t h e i m p l i e d d i l u t i o n e f f e c t , a r e d u c t i o n i n q u a n t i t y of p h o s p h o r u s a l o n g t h e lower Haw R i v e r , s u g g e s t s t h a t t h e o b s e r v e d c h a n g e may b e d u e i n p a r t t o d i l u t i o n and s e d i m e n t a t i o n p r o c e s s e s .

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Comparison of t h e w a t e r q u a l i t y of t h e main New Hope and Haw R i v e r c h a n n e l s was a c c o m p l i s h e d w i t h i n s e a s o n a l s e t s and f o r similar p e r i o d s of t i m e i n o r d e r t o r e f l e c t c o m p a r a b l e r u n o f f c o n d i t i o n s . The q u a l i t y of

n o n p o l l u t e d l a t e r a l s t r e a m s e n t e r i n g t h e Haw R i v e r i n t h i s r e g i o n was compared w i t h t h e q u a l i t y o f t h e main s t e m , A c o n s i s t e n t p a t t e r n o f d i f f e r e n c e

e s t a b l i s h e d t h e m a g n i t u d e of t h e c o m p a r a t i v e p o l l u t i o n l o a d and d e g r a d a t i o n of q u a l i t y . T h i s was p a r t i c u l a r l y a p p a r e n t f o r t h e p a r a m e t e r s of n i t r o g e n and p h o s p h o r u s . A l t h o u g h t h e main r i v e r s were found t o b e c a r r y i n g a s u b s t a n t i a l p o l l u t i o n l o a d i n t e r m s of n o n - b i o l o g i c a l p a r a m e t e r s , t h e downstream s t a t i o n s , p a r t i c u l a r l y i n t h e summer, were found t o h a v e f e w e r numbers of i n d e x o r g a n i s m s t h a n were found i n t h e c o n t r o l s t r e a m s . T h i s c o u l d b e a n i n d i c a t i o n of a c t i v e s e l f - p u r i f i c a t i o n by t h e complex o f c h e m i c a l and

b i o l o g i c a l i n t e r a c t i o n s

.

The marked e f f e c t of c h a n g e i n t h e l o n g - t e r m a v e r a g e r i v e r f l o w on w a t e r q u a l i t y i s i l l u s t r a t i v e of t h e d i f f i c u l t y i n e s t a b l i s h i n g m e a n i n g f u l w a t e r q u a l i t y v a l u e s ( i n c l u d i n g t h e i r r e l a t i o n s h i p t o p r i o r v a l u e s o r e x p e c t e d v a l u e s ) o n a n y s p e c i f i c d a t e . Sampling s e r i e s of c o n s i d e r a b l e l e n g t h a r e r e q u i r e d t o e s t a b l i s h d i r e c t i o n s of q u a l i t y c h a n g e s and t o a s c e r t a i n w h e t h e r s u c h t r e n d s r e f l e c t management e f f o r t s t o improve q u a l i t y .

Two of t h e t h r e e h e a d w a t e r s t r e a m s of t h e New Hope d r a i n a g e t h a t r e c e i v e p o i n t s o u r c e d i s c h a r g e s of t r e a t e d sewage were found t o b e of e x t r e m e l y poor q u a l i t y , a t t h e a p p r o x i m a t e p o i n t where t h e y would b e e n t e r i n g t h e p r o j e c t e d c o n s e r v a t i o n p o o l o f t h e B . E v e r e t t J o r d a n Lake. S i n c e t h e s e s t r e a m s a r e f r e q u e n t l y a t f l o w l e v e l s l e s s t h a n t h e volume of p l a n t e f f l u e n t e n t e r i n g them, a n d t h u s h a v e a n e g l i g i b l e d i l u t i o n e f f e c t , t h e c o s t of t r e a t m e n t t o a t t a i n a sewage t r e a t m e n t p l a n t e f f l u e n t q u a l i t y c o m p a t i b l e w i t h t h e d e s i r e d u s e s of t h e s e s t r e a m s may b e uneconomic. Scheduled p l a n t improvements a t

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Chapel H i l l and a new p l a n t by t h e c i t y of Durham, r e l o c a t e d t o a v o i d s t r e a m s w i t h no s i g n i f i c a n t d i l u t i o n volume,may b e o n l y a p a r t i a l s o l u t i o n i n a t t a i n i n g t h e d e s i r e d s t r e a m q u a l i t y t h a t would f l o w i n t o t h e p r o j e c t e d l a k e .

I t i s recommended t h a t t h i s w a t e r s a m p l i n g s e r i e s b e c o n t i n u e d ,

p a r t i c u l a r l y i n t o t h e p r o s p e c t i v e p e r i o d o f improvements i n w a s t e w a t e r t r e a t - ment f a c i l i t i e s i n t h i s r e g i o n . T h i s w i l l expand t h e d a t a b a s e f o r

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LONG TERM TRENDS I N WATER QUALITY LOWER HAW AND NEW HOPE RIVERS, 1966-1973

INTRODUCTION

To e s t a b l i s h t h e c h e m i c a l , p h y s i c a l and b i o l o g i c a l c h a r a c t e r i s t i c s of s u r f a c e w a t e r s s o a s t o d e r i v e a n o v e r a l l a s s e s s m e n t of w a t e r q u a l i t y r e q u i r e s a s y s t e m a t i c s a m p l i n g program. Such a program s h o u l d b e c o n t i n u e d o v e r a p e r i o d of t i m e s u f f i c i e n t t o i n s u r e a d e q u a t e r e p r e s e n t a t i o n o f s e a s o n a l

v a r i a t i o n s a s w e l l a s f l u c t u a t i o n s i n q u a l i t y which a r e a r e s p o n s e t o r a i n f a l l and c h a n g e s i n r u n o f f , and p o i n t and non-point s o u r c e s of p o l l u t i o n .

F l u c t u a t i o n s i n q u a l i t y a r e of p a r t i c u l a r s i g n i f i c a n c e i f t h e f l o w i n g s t r e a m e n t e r s a l a k e o r impoundment whose w a t e r u s e s r e q u i r e s p e c i f i c q u a l i t y

c h a r a c t e r i s t i c s . I n o t h e r i n s t a n c e s where s u b s t a n t i a l p u b l i c and p r i v a t e i n v e s t m e n t s i n w a s t e t r e a t m e n t p l a n t s a r e t o b e made, w a t e r q u a l i t y

c h a r a c t e r i z a t i o n , d e f i n e d by a s p e c t r u m o f p a r a m e t e r s , i s e s s e n t i a l t o

d e t e r m i n i n g what c h a n g e s i n q u a l i t y m i g h t b e e x p e c t e d . Q u a l i t y b a s e l i n e s a r e needed i f a d d i t i o n a l p o i n t s o u r c e s o f w a s t e w a t e r d i s c h a r g e a r e p r o j e c t e d and t h e economic v i a b i l i t y o f a r e g i o n r e q u i r e s t h a t t h e n a t u r a l p u r i f i c a t i o n c a p a c i t y of a r i v e r b e i n t r o d u c e d a s a b e n e f i t f u n c t i o n i n t h e economic model.

F o l l o w i n g c o n g r e s s i o n a l a u t h o r i z a t i o n f o r t h e c o m p r e h e n s i v e s u r v e y of t h e Cape F e a r B a s i n (1955) and t h e s u b s e q u e n t p l a n n i n g f o r t h e New Hope r e s e r v o i r , t o b e impounded by a dam on t h e Haw R i v e r u p s t r e a m of Moncure, N o r t h C a r o l i n a , c o n t r o v e r s y a r o s e o v e r s e v e r a l a s p e c t s . T h e s e i n c l u d e d t h e b a s i c p r e m i s e f o r t h e dam, f l o o d c o n t r o l , t h e i n t e r p r e t a t i o n of f l o w d a t a and p r o j e c t i o n s o f f l o o d f r e q u e n c i e s , and q u e s t i o n s a b o u t t h e q u a l i t y of t h e w a t e r t h a t would b e impounded. T h i s l a t t e r c o n c e r n was d u e t o t h e s u b s t a n t i a l number o f

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d i s c h a r g e s e n t e r t h e New Hope and Haw R i v e r s . It was s u g g e s t e d t h a t t h e s e s o u r c e s would c o n t r i b u t e s u f f i c i e n t r e s i d u a l o r g a n i c and n u t r i e n t components s o t h a t New Hope Lake would b e of low q u a l i t y . S t a r t i n g i n 1 9 6 6 s e v e r a l w a t e r q u a l i t y s a m p l i n g s t a t i o n s w e r e e s t a b l i s h e d on t h e New Hope and l o w e r Haw R i v e r s . T h e s e were sampled on a r e g u l a r s c h e d u l e and w i t h s u f f i c i e n t f r e q u e n c y t o

d e s c r i b e e x i s t i n g q u a l i t y l e v e l s and t h u s d e r i v e some b a s i s f o r p r o j e c t i n g t h e p o t e n t i a l q u a l i t y i n t h e p l a n n e d impoundment ( 1 , 2)

.

A s r e q u i r e d by f e d e r a l l e g i s l a t i o n , o t h e r f e d e r a l a g e n c i e s c o n c e r n e d w i t h w a t e r p o l l u t i o n h a v e c a r r i e d o u t s t u d i e s t o p r o v i d e i n f o r m a t i o n t o t h e C o r p s of E n g i n e e r s on t h e d e s i g n and o p e r a t i n g s t a n d a r d s of t h i s impoundment ( 3 ) . O t h e r i n v e s t i g a t i o n s have e x t e n d e d t h e n e t w o r k of s a m p l i n g s t a t i o n s o n t h e lower Haw a n d New Hope d r a i n a g e s , i n c l u d i n g n o n - p o l l u t e d l a t e r a l s t r e a m s . T h e s e s t u d i e s i n c l u d e d t h e n a t u r e of t h e b e n t h i c m a c r o i n v e r t e b r a t e s and t h e i r community s t r u c t u r e a s w e l l a s t r a c e m e t a l a n a l y s e s b o t h i n w a t e r and i n t i s s u e s o f s e l e c t e d b e n t h i c i n v e r t e b r a t e s ( 4 ) . S i n c e 1966 and a l m o s t w i t h o u t i n t e r r u p t i o n , t h e New Hope and lower Haw R i v e r s and t h e i r t r i b u t a r i e s h a v e been sampled w i t h a t l e a s t m o n t h l y f r e q u e n c y and i n some s e q u e n c e s t w i c e m o n t h l y . The l o c a t i o n s of t h e s a m p l i n g s t a t i o n s a r e shown o n F i g u r e

I.

The p r o p o s e d N e w Hope Lake ( s u b s e q u e n t l y renamed i n 1974 B . E v e r e t t J o r d a n Lake) w i l l b a c k up from t h e dam s i t e , j u s t below t h e j u n c t i o n of t h e New Hope and Haw R i v e r s . A t t h e c o n s e r v a t i o n p o o l e l e v a t i o n of 216 f e e t , t h e l a k e w i l l h a v e two arms,

o n e e x t e n d i n g o n t h e Haw t o a p o i n t j u s t u p s t r e a m o f S t a t i o n Haw

5 ,

and t h e o t h e r up t h e New Hope V a l l e y t o s l i g h t l y a b o v e S t a t i o n

7 .

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(14)

and a s of t h i s w r i t i n g a r e i n a f i n a l p h a s e of a d j u d i c a t i o n w i t h a judgment i s s u e d i n 1974 by t h e

U.

S . M i d d l e D i s t r i c t C o u r t o f N o r t h C a r o l i n a

( 5 ,

6 ) .

T h i s d e c i s i o n r e q u i r e d t h a t c e r t a i n w a t e r q u a l i t y and t e r r e s t r i a l s t u d i e s b e made t o s u p p l y d e t a i l s c l a i m e d l a c k i n g i n t h e e n v i r o n m e n t a l i m p a c t s t a t e m e n t p r e p a r e d f o r t h i s p r o j e c t by t h e C o r p s of E n g i n e e r s i n 1972 ( 7 ) .

With t h e e n a c t m e n t o f w a t e r p o l l u t i o n c o n t r o l l e g i s l a t i o n i n t h e e a r l y 7 0 ' s by t h e C o n g r e s s , s u b s t a n t i a l e f f o r t s a t r e d u c t i o n o f p o i n t s o u r c e

p o l l u t i o n d i s c h a r g e s e n s u e d . A t t h i s same t i m e e f f o r t s w e r e made t o improve t h e q u a l i t y of w a s t e w a t e r t h r o u g h t h e h i g h l y p u b l i c i z e d r e d u c t i o n o f t h e

p h o s p h a t e c o n t e n t o f h o u s e h o l d d e t e r g e n t s . I n c o n s i d e r a t i o n o f t h e s u b s t a n t i a l m o n e t a r y i n v e s t m e n t s i n w a s t e t r e a t m e n t works and t h e q u a l i t y o f s u b s t a n c e s

t h a t q u i c k l y e n t e r t h e w a s t e w a t e r f l o w and s u b s t a n t i a l l y a f f e c t r e c e i v i n g streams,

t h e q u e s t i o n a r i s e s a s t o w h e t h e r t h e s e a c t i o n s h a v e had a n y p a r t i c u l a r e f f e c t o n t h e w a t e r q u a l i t y of t h e lower Haw a n d New Hope R i v e r s . Through t h e

s y s t e m a t i c s a m p l i n g program, d e s c r i b e d i n t h i s r e p o r t i t s h o u l d b e p o s s i b l e t o d e t e r m i n e w h e t h e r t h e r i v e r q u a l i t y i s i m p r o v i n g , w o r s e n i n g o r n o t c h a n g i n g a t a l l . O t h e r s t u d i e s i n t h i s p e r i o d r e l e v a n t t o t h e p o t e n t i a l q u a l i t y i n t h e B . E v e r e t t J o r d a n Lake i n c l u d e d i n v e s t i g a t i o n s of t h e f e a s i b i l i t y of w a t e r q u a l i t y management o f impoundments and p r e d i c t i v e q u a l i t y m o d e l s f o r t h e Haw R i v e r (8, 9 ) .

SAMPLING

AND ANALYTICAL METHODS

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l a t e r a l s t r e a m s . The s e r i e s o f s t a t i o n s on t h e Haw R i v e r , s t a r t i n g a t t h e community of Saxapahaw and downstream t o a p o i n t a few m i l e s below t h e l o c a t i o n of t h e dam s t r u c t u r e , was s e l e c t e d t o d e t e r m i n e t h e d e g r e e o f r e c o v e r y f r o m t h e s u b s t a n t i a l p o l l u t i o n l o a d i n t r o d u c e d t o t h e h e a d w a t e r

s t r e a m s of t h e Haw from t h e communities o f G r e e n s b o r o , B u r l i n g t o n and Graham a n d many i n d u s t r i a l p o i n t s o u r c e s . The u p p e r d r a i n a g e o f t h e New Hope r e c e i v e s

t h e p o i n t d i s c h a r g e f r o m t h e C h a p e l H i l l sewage t r e a t m e n t p l a n t and several

t r e a t m e n t p l a n t s of t h e c i t y and c o u n t y of Durham. Sampling l o c a t i o n s

e x t e n d e d f r o m t h e v i c i n i t y of t h e p o i n t s o u r c e s n e a r l y t o t h e p o i n t a t which t h e New Hope j o i n s t h e Haw. Gauging s t a t i o n s c l o s e t o S t a t i o n s Haw 5 and Haw 6 on t h e Haw R i v e r and New Hope 1 0 o n t h e New Hope R i v e r h a v e been o p e r a t e d by t h e

U.S.

G e o l o g i c a l Survey f o r many y e a r s . Flow r e c o r d s from t h e s e p o i n t s have been used t o compute t h e w e i g h t o f m a t e r i a l s t r a n s p o r t e d o n d a t e of s a m p l i n g a s w e l l a s a v e r a g e l o a d i n g v a l u e s f o r more e x t e n d e d p e r i o d s of t i m e .

The a n a l y t i c a l methods u s e d d u r i n g t h e p e r i o d of 1966-1973 h a v e u n d e r g o n e l i t t l e c h a n g e which m i g h t h a v e i n t r o d u c e d a r t i f i c i a l movements of a n y t r e n d l i n e . N i t r o g e n and phosphorus s p e c i e s have been d e t e r m i n e d by T e c h n i c o n A u t o - a n a l y z e r s which h a v e performed w i t h a h i g h o r d e r o f c o n s i s t e n c y . I n o t h e r p r o c e d u r e s S t a n d a r d Methods g e n e r a l l y h a s b e e n f o l l o w e d w i t h

c o n s i d e r a t i o n f o r more r e c e n t r e f i n e m e n t s recommended by t h e E n v i r o n m e n t a l P r o t e c t i o n Agency ( 1 0 , 1 1 ) . D e t a i l s of t h e p r o c e d u r e s have been p r e v i o u s l y d e s c r i b e d ( 4 ) . A l l w a t e r q u a l i t y p a r a m e t e r s w e r e d e t e r m i n e d a t e a c h s a m p l i n g

s t a t i o n o n c e s a m p l i n g was i n i t i a t e d . O c c a s i o n a l g a p s o c c u r r e d d u e t o

m i s h a n d l i n g of s a m p l e s , b u t t h e r e c o r d i s r e l a t i v e l y c o m p l e t e . T a b l e 1 l i s t s

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S t a t i o n 1 2

4

5 6 7 8 8 A 1 0 11 12**

S t a t i o n 1 2 3 4 5 6 7 8 9 1 0 11 1 2 13** 14** 15** Water Stream

Morgan Creek Morgan Creek T h i r d F o r k New Hope Creek Morgan Creek New Hope R i v e r Whit eoak Creek Beaver Creek New Hope R i v e r N o r t h e a s t Creek Bush Creek

Stream Haw R i v e r Haw R i v e r Haw R i v e r Haw R i v e r Haw R i v e r Haw R i v e r Cane Creek Cane Creek C o l l i n s Creek T e r r e l l Creek F e r r e l l Creek Dry Creek Robeson Creek Pokeberry Creek S t i n k i n g Creek

T a b l e 1

Q u a l i t y Sampling L o c a t i o n s New Hope R i v e r

County Orange Orange Durham Durham Chatham Cha tham Chatham Chatham Cha tham Chatham Chat ham

Rout e Number

Off 1900

-

Chapel H i l l Treatment P l a n t F i n l e y Golf Course Road

SR 7 5 1 1107 1109 1008 1008 1008 17 00 SR 751

17 1 5

Haw R i v e r

County Alamanc e

Alamance-Orange C ha tham

Chatham Chatham Chat ham Orange Alamance Chatham Cha tham Chat ham Chat ham Chatham Chat ham Chatham

Route Number

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S t a t i o n

NH-1 NH- 2

NH-4

NH- 5

NH- 6 NH-7

T a b l e 2

P e r i o d s of Sampling Used i n Data A n a l y s i s

D a t e s

November 1966-March 1970

I t 11 11 I I

November 1966-October 1973

I I II I 1 I I

November 1967-March 1970

11 11 11 11

November 1967-October 1 9 7 3

A p r i l 1970-October 1973

J a n u a r y 1971-0ctober 1973

11 11 I 1 II

November 1970-October 1 9 7 3

11 11 I! 11

11 II 11 1 1

1 1 I 1 1 I I I

11 11 11 I 1

November 1970-0c t o b e r 1973

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T a b l e 3

Water Q u a l i t y P a r a m e t e r s

Determined i n t h e 1966-1973 Sampling S e r i e s Lower Haw and New Hope R i v e r s

T e m p e r a t u r e O C

R e s i d u e m g / l

T u r b i d i t y JTU ( J a c k s o n T u r b i d i t y U n i t s ) C o n d u c t i v i t y pmhos (micro mhos/cm2) D i s s o l v e d oxygen m g / l

D i s s o l v e d oxygen % s a t u r a t i o n

BOD m g / l (5-day B i o c h e m i c a l Oxygen Demand) Carbon m g / l ( T o t a l O r g a n i c )

S o l u b l e Carbon m g / l ( S o l u b l e O r g a n i c , p a s s 0 . 4 5 ~ membrane f i l t e r ) I n o r g a n i c Carbon m g / l

T o t a l N i t r o g e n mg/l K j e l d a h l N i t r o g e n m g / l

NO +NO3-Nitrogen m g / l 2

T o t a l P h o s p h o r u s m g / l O r t h o p h o s p h a t e m g / l (PO4-P)

C h l o r o p h y l l - K l e t t U n i t s ( 0 . 4 5 ~ membrane f i l t e r e d sample e x t r a c t e d w i t h a c e t o n e and r e a d a t 640 on K l e t t p h o t o m e t e r ) C o l i f o r m s ~ o . / m l T o t a l c o l i f o r m , d i r e c t c o u n t of c o l o n i e s

on MF and s p e c i f i c media

Ent e r o c o c c i N O . / m l D i r e c t c o u n t o f c o l o n i e s on MF and s p e c i f i c media

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DATA PRESENTATION AND DATA ANALYSIS

A l t h o u g h t h e t i t l e of t h i s r e p o r t i m p l i e s a d a t a r e c o r d o f some l e n g t h , t h e s e v e n y e a r p e r i o d d e s c r i b e d i s r e l a t i v e l y s h o r t and h a r d l y c o m p a r a b l e t o r e c o r d s of s e v e r a l d e c a d e s . R e l a t i v e l y few s t u d i e s of r i v e r w a t e r q u a l i t y h a v e b e e n c o n d u c t e d f o r a s u f f i c i e n t p e r i o d o f t i m e t o l e n d t h e m s e l v e s t o t h e

I t y p e o f s t a t i s t i c a l a n a l y s i s t h a t c o m p e t e n t l y d e f i n e s and i n t e r p r e t s

m e a s u r e a b l e t r e n d s i n t h e o b s e r v e d d a t a . The l a c k of s e r i e s 0 5 a d e q u a t e l e n g t h h a s b e e n d i s c u s s e d r e c e n t l y i n a r e v i e w of a v a i l a b l e i n f o r m a t i o n o n t h e m a j o r r i v e r s o f t h e U n i t e d S t a t e s ( 1 2 ) .

I f d a t a i s c o l l e c t e d a t s u f f i c i e n t l y f r e q u e n t i n t e r v a l s from a p e r i o d i c a l l y v a r i a b l e s y s t e m , t h e d a t a l e n d s i t s e l f t o some form o f t i m e - s e r i e s a n a l y s i s . T h i s method of a n a l y s i s of w a t e r q u a l i t y d a t a i s p a r t i c u l a r l y good when t h e d a t a i s r e c o r d e d on a c o n t i n u o u s b a s i s . Through F o u r i e r a n a l y t i c a l t e c h n i q u e s background n o i s e of t h e s y s t e m c a n b e e x t r a c t e d and t r u e v a r i a t i o n d e t e r m i n e d

( 1 3 , 4 Where t h e d a t a h a s b e e n c o l l e c t e d o v e r a l o n g e r p e r i o d of t i m e b u t samples were t a k e n l e s s f r e q u e n t l y , r e g r e s s i o n a n a l y s i s between t h e c a u s a l l y r e l a t e d v a r i a b l e s might g i v e some i n d i c a t i o n a s t o t h e n a t u r e and d i r e c t i o n of l o n g term t r e n d s ( 1 5 ) . Such a n a l y s i s i s p a r t i c u l a r l y u s e f u l where t h e h y d r o g r a p h i c r e c o r d of r i v e r f l o w i s e s s e n t i a l l y c o m p l e t e f o r t h e p e r i o d o f a n a l y s i s . Using t h e s e t e c h n i q u e s , r e c e n t s t u d i e s of t r e n d s i n r i v e r w a t e r q u a l i t y h a v e worked w i t h a sample s e r i e s of o v e r 20 y e a r s ( 1 6 ) . U n t i l t h e d a t a s e r i e s on t h e Haw and t h e New Hope i s p o s s i b l y t w i c e t h e c u r r e n t l e n g t h and u n t i l t h e r e i s a c l e a r e r u n d e r s t a n d i n g of t h e impact o f c h a n g e s i n f l o w on q u a l i t y d e t e r m i n a t i o n s i n t h i s p a r t i c u l a r b a s i n , i t would b e p r e s u m p t i o u s t o a p p l y more s o p h i s t i c a t e d forms of a n a l y s i s t o t h e d a t a . A t t h i s p o i n t a n a n a l y s i s h a s been a t t e m p t e d b a s e d o n a mean v a l u e f o r e a c h w a t e r q u a l i t y

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i n d i s c h a r g e .

I n t h e f i r s t e x a m i n a t i o n o f a " l o n g r u n " of d a t a , t h e g r a p h i c p r e s e n t a t i o n s d e s c r i b e d a d i s t i n c t s e a s o n a l c o m p o n e n t , p a r t i c u 1 a r l y i n a n o n c o n s e r v a t i v e

p a r a m e t e r s u c h a s t e m p e r a t u r e ( 2 ) . E s p e c i a l l y s t r i k i n g was t h e p e r i o d d e s c r i b e d by t h e s e a s o n a l s h i f t o f t h e t e m p e r a t u r e c u r v e . The c u r v e

c o n s i s t e n t l y dropped below 10°C a b o u t November 1 o f e a c h y e a r and r o s e a b o v e 10°C a b o u t A p r i l 1, t h u s d i v i d i n g t h e y e a r i n t o two s e g m e n t s which a r e a l m o s t e q u a l i n l e n g t h b u t c l e a r l y d i f f e r e n t i n t e m p e r a t u r e . From November t o March, c o n s e r v a t i v e and n o n c o n s e r v a t i v e m a t e r i a l s and s u b s t a n c e s i n t e r a c t a t low w a t e r

t e m p e r a t u r e s ; 'from A p r i l t o O c t o b e r , t h e i n t e r a c t i o n o c c u r s a t c o n s i d e r a b l y h i g h e r w a t e r t e m p e r a t u r e s . A s a c o n s e q u e n c e o f t h i s o b s e r v a t i o n , A p r i l 1 was a d o p t e d a s t h e b e g i n n i n g o f t h e e n v i r o n m e n t a l y e a r f o r p u r p o s e s of a q u a t i c o b s e r v a t i o n s i n t h i s r e g i o n . The p r e s e n t a n a l y s i s of w a t e r q u a l i t y s a m p l e s c o l l e c t e d o v e r t h e p e r i o d o f 1966-1973 c o n c l u d e s w i t h t h o s e t a k e n t h r o u g h O c t o b e r , 1 9 7 3 . The v a r i o u s s t a t i s t i c a l t r e a t m e n t s of t h e d a t a a r e b a s e d o n t h e c a l e n d a r s e q u e n c e s of November 1

-

March 3 1 and A p r i l 1

-

O c t o b e r 3 1 .

I n t h e e x a m i n a t i o n o f d a t a c o l l e c t e d o n e i t h e r a m o n t h l y o r t w i c e m o n t h l y b a s i s , t h e v a l u e s r e p r e s e n t e d i n Appendices

I.-

I11 a r e t h e mean of e a c h s e r i e s and a n e s t i m a t e o f t h e c e n t r a l 75 p e r c e n t i l e o f e a c h s e r i e s .

Thus, t h e m a g n i t u d e of t h e v a r i a t i o n a r o u n d t h e mean i s d e s c r i b e d by t h e r a n g e of v a l u e s c e n t r a l t o t h e mean v a l u e encompassing 75% o f t h e s a m p l e

s e r i e s . T h i s r a n g e o f v a l u e s a v o i d s r e p o r t i n g t h e maximum and minimum v a l u e s which i n many i n s t a n c e s a r e v a l u e s r e p r e s e n t a t i v e o f o c c a s i o n a l e x t r e m e

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r a i n s , o f t e n i n t r o d u c i n g a d d i t i o n a l s u b s t a n c e s which l o w e r w a t e r q u a l i t y . When s t r e a m f l o w d a t a was a v a i l a b l e a t o r n e a r a s a m p l i n g p o i n t , t h e l o a d i n g o r t r a n s p o r t o f oxygen, BOD, c a r b o n , s e v e r a l n i t r o g e n and p h o s p h o r u s s p e c i e s , and r e s i d u e h a s b e e n computed and a v e r a g e d f o r v a r i o u s sample s e r i e s i n t h e two s e a s o n a l s e q u e n c e s .

The g r a p h i c p r e s e n t a t i o n s of w a t e r q u a l i t y d a t a , d e s c r i b e d f o r t h e two s e a s o n a l s e q u e n c e s of e a c h y e a r , a r e p r e s e n t e d i n a set o f f i g u r e s f o r e a c h s t a t i o n i n Appendix 1. I n a d d i t i o n , f o r t h e s t a t i o n s where t h e d a t a s e r i e s was of s u f f i c i e n t l e n g t h , t a b l e s h a v e b e e n p r e p a r e d f o r t h e p e r i o d 1966-1973 which d e s c r i b e t h e mean v a l u e s o f 20 w a t e r q u a l i t y p a r a m e t e r s i n t h r e e - y e a r

segments of t h e two a n n u a l s e a s o n a l components. T h u s , d a t a from t h e t h r e e November-March p e r i o d s of t h e y e a r s 1966-1969 and t h e same p e r i o d f o r 1970- 1972 h a v e b e e n a v e r a g e d and t h e c e n t r a l 75 p e r c e n t i l e s c a l c u l a t e d . The d a t a c o l l e c t e d i n t h e A p r i l - O c t o b e r p e r i o d f o r t h e y e a r s 1967-1969 and 1971-1973 have been s i m i l a r l y t r e a t e d . S i n c e a l l s t a t i o n s were n o t s y s t e m a t i c a l l y c o l l e c t e d t h r o u g h t h e p e r i o d of A p r i l - O c t o b e r 1 9 7 0 , t h i s p e r i o d was n o t i n c l u d e d i n t h e s e c o m p u t a t i o n s b u t w i l l b e found p r e s e n t e d f o r s e v e r a l s t a t i o n s i n t h e g r a p h i c d e p i c t i o n s of w a t e r q u a l i t y c h a n g e s . T h e s e t a b l e s of t h r e e y e a r s a v e r a g e d d a t a a r e assembled i n Appendix 11.

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w i l l be i n s t r u m e n t a l i n m o n i t o r i n g c h a n g e s i n r i v e r q u a l i t y upon c l o s u r e o f New Hope Dam.

RESULTS

The p u r p o s e o f t h i s r e p o r t i s t o p r e s e n t t h e w a t e r q u a l i t y d a t a c o l l e c t e d f o r t h e l o w e r Haw and New Hope R i v e r s i n a f o r m u s e f u l t o w a t e r q u a l i t y

managers and o t h e r s c o n c e r n e d w i t h w a t e r q u a l i t y c h a n g e s i n r i v e r s s u b j e c t e d t o heavy p o l l u t i o n l o a d s from w a s t e w a t e r t r e a t m e n t p l a n t s and o t h e r p o i n t s o u r c e d i s c h a r g e s . A l t h o u g h t h e s e v e n y e a r p e r i o d of r e c o r d would a p p e a r t o b e of s u f f i c i e n t l e n g t h t o e s t a b l i s h c l e a r t r e n d s , s h o u l d t h e y e x i s t , t h e t e n d e n c y o f t h e s e two r i v e r s t o f l a s h f l o o d when s u b j e c t t o t h e i n t e r m i t t e n t a n d i n t e n s e r a i n f a l l p a t t e r n c h a r a c t e r i s t i c o f t h e C a r o l i n a s m i g h t t e n d t o o b s c u r e q u a l i t y t r e n d s . E x a m i n a t i o n o f t h e g r a p h i c p r e s e n t a t i o n s i n

Appendix I c o n f i r m s t h e e x t r e m e v a r i a b i l i t y of s e v e r a l o f t h e w a t e r q u a l i t y p a r a m e t e r s . I n o t h e r i n s t a n c e s t h e p a r a m e t e r showed l i t t l e v a r i a b i l i t y a s i n d i c a t e d by t h e r a n g e o f t h e 75 p e r c e n t i l e , and was a p p a r e n t l y l i t t l e a f f e c t e d by v a r i a t i o n s i n f l o w . E f f e c t s of f l o w v a r i a t i o n were p a r t i c u l a r l y pronounced a t t h e s t a t i o n s ' head w a t e r s t r e a m s and were e v i d e n t l y damped a t t h e s a m p l i n g l o c a t i o n s a l o n g t h e s t r e t c h e s of t h e l a r g e r w a t e r c o u r s e s .

The s h a r p c h a n g e s i n s e v e r a l p a r a m e t e r s t h r o u g h t h e summer of 1 9 7 0 (which shows a s a gap on s e v e r a l f i g u r e s ) might r a i s e q u e s t i o n s a s t o p o s s i b l e

a n o m a l i e s i n t h e s a m p l i n g o r a n a l y t i c a l s y s t e m . However, a t S t a t i o n s Haw 5

and Haw 6 , a s w e l l a s New Hope 7 , 8 , 8 4 and 1 0 , c o n t i n u i t y of s a m p l i n g d u r i n g t h i s p e r i o d was m a i n t a i n e d . Average v a l u e s f o r a l l p a r a m e t e r s a t t h e s e

(23)

p a r a m e t e r s . T h i s was p a r t i c u l a r l y e v i d e n t a t s t a t i o n s c l o s e t o p o i n t s o u r c e d i s c h a r g e s of sewage t r e a t m e n t p l a n t s , s h a r p c h a n g e s b e i n g less e v i d e n t f u r t h e r downstream. T h i s was b e s t s e e n a t t h e New Hope s t a t i o n s and a l o n g t h e s t a t i o n s on t h e main s t r e a m o f t h e Haw d r a i n a g e .

I n o r d e r t o show t h i s 1970 c h a n g e , T a b l e 4 , d e r i v e d from Appendix I , l i s t s t h e a f f e c t e d p a r a m e t e r s , and t h e d i r e c t i o n of t h e i r c h a n g e . Almost w i t h o u t e x c e p t i o n t h e d i r e c t i o n o f c h a n g e o f t h e n o n c o n s e r v a t i v e s u b s t a n c e s i s t h a t o f a n improvement i n w a t e r q u a l i t y , e . g . l o w e r v a l u e s of NH3-N and K j e l - N a n d h i g h e r v a l u e s of N02+N03-N, i n d i c a t i v e o f e a r l i e r n i t r i f i c a t i o n i n t h e n a t u r a l

p u r i f i c a t i o n s y s t e m of t h e f l o w i n g s t r e a m . Lower c o n d u c t i v i t y (by d i l u t i o n ) and h i g h e r r e s i d u e (from i n c r e a s e d e r o s i o n ) r e f l e c t i n c r e a s e d f l o w , a r e s u l t of h i g h e r r u n o f f . The downward s h i f t i n q u a n t i t y of PO4--P and T o t a l - P a t t h e upper Haw R i v e r s a m p l i n g s i t e s , Haw 1, Haw 2, and Haw 3 , became l e s s e v i d e n t f u r t h e r downstream a t Haw 4 and Haw 5 .

Changes i n R i v e r Flow

To e s t a b l i s h c h a n g e s i n f l o w r a t e s a s a p r i n c i p a l s o u r c e of t h e s h i f t i n q u a l i t y i n 1 9 7 0 , f l o w d a t a f o r Haw

5

and NH 1 0 were grouped i n t o t h e m o n t h l y s e q u e n c e s f o r t h e two e n v i r o n m e n t a l p e r i o d s ( T a b l e s 5 a n d 6 ) . The p r e and p o s t 1 9 7 0 p e r i o d s of f l o w a l s o were a v e r a g e d ( T a b l e 7 ) . The c h a n g e , a s u b s t a n t i a l i n c r e a s e i n f l o w f o r b o t h "summer" and " w i n t e r , " f u l l y j u s t i f i e s t h e c o n c l u s i o n t h a t t h e a p p a r e n t g e n e r a l improvement i n w a t e r q u a l i t y was p r i m a r i l y d u e t o i n c r e a s e d r i v e r f l o w and d i l u t i o n .

I n a r i v e r s y s t e m where w a t e r q u a l i t y may b e s e n s i t i v e t o c h a n g e s i n r u n o f f , c h a n g e s t h a t d e s c r i b e a n improvement i n q u a l i t y a r e m e a n i n g f u l and a r e n o t a s h o r t t e r m e f f e c t d u e t o d i l u t i o n by r a i n f a l l i f c e r t a i n c o n d i t i o n s a r e m e t .

For example i f a c o n s e r v a t i v e q u a l i t y p a r a m e t e r s u c h a s c o n d u c t i v i t y s h o u l d

i n c r e a s e i n c o n c e n t r a t i o n w i t h d e c r e a s e i n r u n o f f , t h i s would i n d i c a t e l e s s f r e s h w a t e r f o r d i l u t i o n , I f a t t h e same t i m e , t h e q u a l i t y of a n o n c o n s e r v a t i v e

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T a b l e 4

Apparent Marked S h i f t s i n Q u a n t i t y of

S p e c i f i c P a r a m e t e r s P r e and P o s t April-October 1970 A s Noted on F i g u r e s of Appendix I

N o t a t i o n of "Winter" o r "Summer" I n d i c a t e s Change Only Apparent i n t h e November-March o r April-October P e r i o d s , Otherwise Change i n Both Seasons

S t a t i o n s Parameter

C o n d u c t i v i t y PO4-P

Total-P

T o t a l N

-

Winter C o n d u c t i v i t y DO

-

Winter

N02+N03-N

-

Summer T o t a l N

DO % S a t .

-

Summer NH3 -N

Kj

el-N

C o n d u c t i v i t y DO % S a t .

-

Summer D 0

NH3

-N K j el-N DO % S a t .

N02+N03-N

-

Winter

Nd3-N

-

Winter T o t a l N

-

Winter

D i r e c t i o n of Change D e c r e a s e

D e c r e a s e D e c r e a s e D e c r e a s e D e c r e a s e I n c r e a s e I n c r e a s e D e c r e a s e I n c r e a s e D e c r e a s e D e c r e a s e D e c r e a s e I n c r e a s e I n c r e a s e D e c r e a s e D e c r e a s e I n c r e a s e D e c r e a s e Decrease D e c r e a s e

N02+N03-N

-

Winter D e c r e a s e

T u r b i d i t y Residue

C o n d u c t i v i t y

-

Winter DO % S a t .

-

Summer P04-P

-

Winter T o t a l P

NH3 -N

K j el-N

Total-N

-

Winter

I n c r e a s e I n c r e a s e Decrease

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T a b l e

4

( c o n t i n u e d )

S t a t i o n s

Haw-2

Parameter

-

Winter Residue

DO % S a t .

-

Winter

PO4-P

-

Winter

T o t a l P

-

Winter

NH3-N

-

Winter

K j el-N

To tal-N Winter

Residue

-

Winter

PO4-P

-

Winter

NH3-N

-

Winter

K j el-N T o t a l N E n t e r o c o c c i

Residue

DO

-

Winter

N02SN03-N

-

Summer

NH3-N

-

Winter

K j el-N

C o n d u c t i v i t y NH3 -N

K j el-N

Total-N

-

Winter

D i r e c t i o n of Change

D e c r e a s e I n c r e a s e I n c r e a s e Decrease Decrease D e c r e a s e Decrease D e c r e a s e

I n c r e a s e D e c r e a s e Decrease Decrease Decrease Decrease I n c r e a s e

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T a b l e 5

Average R i v e r Flow a t S t a t i o n NH-10 f o r Monthly Sequences Used i n Water Q u a l i t y A n a l y s i s

Month Year cfs Year cfs Year c f s Year cfs Year c f s Year cfs Year c f s

- - -

Nov

.

1966 29.9 1967 38.4 1968 8 9 . 4 1 9 6 9 26.5 1 9 7 0 1 1 5 1 9 7 1 1 9 2 1972 748

Dec

.

60.7 432 1 2 1 1 9 1 1 2 1 213 8 27

J a n . 1967 1 2 6 1968 664 1969 245 1 9 7 0 1 4 0 1 9 7 1 533 1 9 7 2 3 1 1 1 9 7 3 670

Feb. 553 1 0 3 58 5 716 827 785 1216

March 1 2 0 38 5 802 4 6 1 562 1 0 8 943

1

Mean

e-L

-

178 - 3 24

-

3 68

-

3 07

-

432

-

322

CI\

I

A p r i l 1 3 5 1 3 1 1 6 4 530 315

J u n e 6 1 . 0 77.6 206 23.0 8 1 . 3 243 374

J u l y 68.2 127 28.5 2 7 . 1 39.4 7 3 . 3 224

Aug

.

249 1 6 . 5 292 76.4 1 4 3 1 9 2 1 1 2

S e p t

.

46.7 1 0 . 6 11 2 1 5 . 9 243 9 1 . 5 31.2

Oct. 37.8 23.2 1 5 2 2 2 . 1 1 0 9 3 248

*

M e a n

_-

1 2 0

_-

7 0 1 4 2

_-

11 1

_-

3 1 4

-

252

_-

302

(27)

Month

--

N O ~ .

Dec

.

J a n . Feb

.

March

I

P Mean

I

A p r i l

May

J u n e J u l y Aug

.

Sepr

.

O c t .

Mean

Y e a r

1 9 6 6

1967

c f s 291 505 6 6 1 167 3 63 1 752

-

433 720 255 244 8 1 3 1 9 2 1 4 3

4 0 0 *Gauge d i s c o n t i n u e d d u e

T a b l e 6

Average R i v e r Flow a t S t a t i o n Haw-5 f o r Monthly Sequences Used i n Water Q u a l i t y A n a l y s i s

Year c f s

-

1967 1 5 1 1656 1968 2398

643 2062

Year c f s

-

1968 564

550

1969 924

177 6 2070

Year c f s

-

1969 225

905 1 9 7 0 659 1 9 9 1 1 3 6 3

t o b a c k f l o o d i n g f r o m B. E v e r e t t J o r d a n D a m

Year c f s

-

1970 946

58 1 1 9 7 1 1 2 5 1

2895 2041

Year c f s

-

1 9 7 1 1 3 2 3 1129 1972 1274

2465

8 62

Year c f s

-

(28)

(29)

s u b s t a n c e s u c h a s PO4-P s h o u l d d e c r e a s e a s f l o w d r o p p e d t h i s would b e a n i n d i c a t i o n o f improvement i n q u a l i t y . C e r t a i n s t a t i o n s , when examined f o r l o n g t e r m t r e n d s , show s u c h c h a n g e s of q u a l i t y .

Water Q u a l i t y Changes a s a Consequence o f Change i n R i v e r Flow

Water q u a l i t y c h a n g e s a t S t a t i o n New Hope 7 (Appendix 11) i n d i c a t e t h a t w i t h i n c r e a s e d r u n o f f , t h e p r e and p o s t 1970 c o m p a r i s o n , r e s i d u e and t u r b i d i t y i n c r e a s e d s i g n i f i c a n t l y when t h e f i r s t and second w i n t e r p e r i o d s a r e compared. R e s i d u e i n c r e a s e d i n t h e c o m p a r i s o n o f t h e summer p e r i o d s . C o n d u c t i v i t y

d e c r e a s e d p o s t 1970 from t h e p r i o r t h r e e - y e a r s e q u e n c e . A t t h e same t i m e , d i s s o l v e d oxygen c o n c e n t r a t i o n s on t h e a v e r a g e r o s e . T h i s was i n r e s p o n s e t o a n i n c r e a s e i n r u n o f f volume, s i n c e t h e added f l o w a l s o d e c r e a s e d BOD by d i l u t i o n . The r e s u l t was a n i n c r e a s e i n p e r c e n t s a t u r a t i o n o f D O . While t h e w i n t e r and summer p e r i o d s f o r t h e second o f e a c h of t h e t h r e e - y e a r s e q u e n c e s

showed a r e d u c t i o n i n k j e l d a h l and ammonia n i t r o g e n , t h e mean v a l u e o f n i t r i t e - n i t r a t e n i t r o g e n showed a d e c r e a s e i n t h e w i n t e r b u t a s u b s t a n t i a l

i n c r e a s e d u r i n g t h e summer. P h o s p h o r u s , however, d e c r e a s e d i n b o t h t i m e p e r i o d s a s r i v e r f l o w i n c r e a s e d . A t S t a t i o n New Hope 1 0 t h e same d i l u t i o n e f f e c t of i n c r e a s e d r u n o f f was e v i d e n t i n t h e c o m p a r a b l e " w i n t e r " and "summer" p e r i o d s .

S t a t i o n Haw 1 i s t h e p o i n t a t which t h e Haw R i v e r , p o l l u t e d from u p s t r e a m s o u r c e s , e n t e r s i t s f r e e - f l o w i n g s t r e t c h f o r a d i s t a n c e of some 23 m i l e s t o S t a t i o n Haw 5 . The a v e r a g e c h a n g e i n r e s i d u e and t u r b i d i t y a t Haw 1 c o n f i r m e d i n c r e a s e d r u n o f f , a s d i d t h e d e c r e a s e i n c o n d u c t i v i t y . S i m i l a r l y , i n t h e comparison of t h e summer p e r i o d s f o r t h e d r y and wet y e a r s , t h e c h a n g e i n q u a n t i t y of d i s s o l v e d oxygen and p e r c e n t s a t u r a t i o n a l s o c o n f i r m e d a n i n c r e a s e i n d i l u t i o n w a t e r . Changes i n BOD were n o t of s u f f i c i e n t m a g n i t u d e t o b e of c o n c e r n . T o t a l n i t r o g e n and

NH3-N

t e n d e d t o show a d e c r e a s e i n q u a n t i t y from

-

1 9

-

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d r y t o wet y e a r s , e x c e p t f o r t h e s i m i l a r h i g h e r n i t r i f i c a t i o n d u r i n g t h e summers w i t h a marked i n c r e a s e i n c o n c e n t r a t i o n o f N02+N0 n i t r o g e n . P h o s p h o r u s showed

3

a d e c r e a s e from d r y t o wet y e a r s , a p r o b a b l e d i l u t i o n e f f e c t . A t S t a t i o n Haw 5 ,

f o l l o w i n g p a s s a g e t h r o u g h t h e f r e e - f l o w i n g s t r e t c h of r i v e r , t h e e f f e c t s d u e t o a n i n c r e a s e d r u n o f f were s t ill a p p a r e n t i n t h e p a r a m e t e r s of r e s i d u e , t u r b i d i t y and c o n d u c t i v i t y . A t t h i s l o c a t i o n t h e d i f f e r e n c e s b e t w e e n d r y and wet y e a r s were no l o n g e r d i s c e r n i b l e i n d i s s o l v e d oxygen, p e r c e n t s a t u r a t i o n D O , o r BOD. N i t r o g e n compounds a t Haw 5 t e n d e d t o show a d e c r e a s e f r o m t h e d r y t o wet y e a r s , e x c e p t t h e N02+N03-N which showed l i t t l e o r no c h a n g e between t h e p e r i o d s o f low and h i g h f l o w . P h o s p h o r u s , o n t h e o t h e r h a n d , c o n t i n u e d t o e x h i b i t a s u b s t a n t i a l d e c r e a s e i n b o t h w i n t e r and summer s e q u e n c e s comparing t h e d r y and wet p e r i o d s . The p e r s i s t e n c e of t h i s p a t t e r n m i g h t b e i n d i c a t i v e o f some r e d u c t i o n i n q u a n t i t y

e n t e r i n g a t p o i n t d i s c h a r g e s u p s t r e a m . However, s i n c e n e t change i n t o t a l t r a n s p o r t ( l b s / d a y ) o f p h o s p h o r u s i n c r e a s e d by

24

p e r c e n t , t h e r e d u c t i o n i n c o n c e n t r a t i o n may b e a p a r t i a l a d s o r p t i o n and s e d i m e n t a t i o n e f f e c t .

Loading

I n t h e c o m p u t a t i o n o f l o a d i n g ( l b s i d a y ) a t S t a t i o n New Hope 1 0 , t h e h i g h e r r u n o f f was e v i d e n t i n t h e d r m a t i c c h a n g e s i n mean v a l u e s between t h e p e r i o d s o f 1966-1969 and 1970-1972 f o r t h e w i n t e r a s w e l l a s t h e summer (Appendix 11). The u n u s u a l i n c r e a s e o f o v e r 1000%

i n

r e s i d u e r e f l e c t s t h e r o a d r e l o c a t i o n work t h a t was s t a r t e d i n 1 9 7 0 u p s t r e a m o f NH-10 ( T a b l e 8 ) . DO and BOD a l s o i n c r e a s e d

s h a r p l y . Whereas i n t h e w i n t e r p e r i o d t o t a l n i t r o g e n changed l i t t l e , d u r i n g t h e summer t h e q u a n t i t y o f n i t r o g e n i n t h e r i v e r was n e a r l y t w i c e a s g r e a t . T h i s r e f l e c t e d p r i m a r i l y a m a j o r i n c r e a s e i n n i t r i t e - n i t r a t e n i t r o g e n i n b o t h summer and w i n t e r c o m p a r i s o n s of t h e d r y and wet y e a r s . T o t a l p h o s p h o r u s p a r a l l e l e d t h e i n c r e a s e i n r u n o f f w i t h a s u b s t a n t i a l i n c r e a s e i n d a i l y l o a d . The p r o b a b l e s o u r c e of t h i s c h a n g e was added c o n t r i b u t i o n s f r o m b o t h p o i n t and n o n - p o i n t s o u r c e s o f

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R e s i d u e DO

BOD

T o t a l Carbon S o l u b l e Carbon I n o r g a n i c Carbon T o t a l N i t r o g e n K j e l d a h l N i t r o g e n N02+N03 -N

NH3 -N

T o t a l P h o s p h o r u s O r t h o p h o s p h a t e R i v e r f low

T a b l e 8

P e r c e n t Change i n Mean V a l u e s Loading

l966-69/l970-7 2 November-March

l967-7O/l97 1-73 April-Oc t o b e r

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t h e e x p a n d i n g u r b a n a r e a s of C h a p e l H i l l and Durham.

I n t h e c o m p a r i s o n o f w i n t e r p e r i o d s , S t a t i o n Haw 5 showed a r e d u c t i o n o f 30% i n r e s i d u e l o a d i n g . However, t h i s p a r a m e t e r i n c r e a s e d by 37% i n t h e c o m p a r i s o n o f t h e d r y and wet p e r i o d s f o r t h e summer s e q u e n c e s . S i n c e a l l

c o n s t r u c t i o n a c t i v i t y on t h e dam and r e s e r v o i r i s downstream o f t h i s s t a t i o n , a g g r a v a t e d l a n d e r o s i o n was n o t e v i d e n t . The dry-wet y e a r s c o m p a r i s o n o f DO showed t h e i n c r e a s e e x p e c t e d f r o m a n i n c r e a s e i n f l o w . BOD had o n l y a minor l o a d i n g i n c r e a s e i n t h e w i n t e r p e r i o d w i t h a more s u b s t a n t i a l i n c r e a s e o f 28% i n t h e summer p e r i o d c o m p a r i s o n s . T o t a l N showed l i t t l e c h a n g e i n t h e w i n t e r p e r i o d c o m p a r i s o n s and o n l y a s l i g h t summer i n c r e a s e of 1 5 % . Major l o n g - t e r m e f f e c t s were s e e n i n t h e c h a n g e s i n l o a d of k j e l d a h l n i t r o g e n , w h i c h

d e c r e a s e d s h a r p l y by 32% and 3 0 % , w i n t e r and summer c o m p a r i s o n s , and ammonia n i t r o g e n , down 38% and 4 5 % , w i n t e r and summer c o m p a r i s o n s r e s p e c t i v e l y . O f f s e t t i n g t h e s e n i t r o g e n o u s component d e c r e a s e s were t h e i n c r e a s e s i n

N02+N03-N, 95% and 85% i n t h e w i n t e r and summer,dry and wet y e a r c o m p a r i s o n s . I n c o n t r a s t , t o t a l p h o s p h o r u s i n c r e a s e d c o u n t e r t o a n y i n d i c a t e d d i l u t i o n ef f e e t by 33% a n d 24% ( w i n t e r and summer, d r y and w e t ) . O r t h o p h o s p h a t e l o a d i n g , however, d e c r e a s e d i n t h e w i n t e r d r y and wet c o m p a r i s o n by 22% b u t i n c r e a s e d i n t h e summer p e r i o d c o m p a r i s o n b y 1 9 % . The c o n c l u s i o n t h a t may b e drawn f r o m t h i s s e r i e s of c h a n g e s i s t h a t t h e h i g h e r f l o w s p r o v i d e d a c a p a c i t y

f o r i n c r e a s e d r a t e of n i t r i f i c a t i o n e v e n though t h e t o t a l amount o f n i t r o g e n remained a p p r o x i m a t e l y t h e same. T o t a l P , however, showed a n e t i n c r e a s e i n l o a d , n e g a t i n g a n y d i l u t i o n e f f e c t .

Water Q u a l i t y - L a t e r a l S t r e a m s Lower Haw R i v e r

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p e r i o d S t a t i o n Haw 6 downstream of t h e New Hope Dam s i t e was a l s o e s t a b l i s h e d and sampled o n a monthly b a s i s . T h e s e s e v e n s t a t i o n s and t h e i r a v e r a g e w a t e r q u a l i t y c h a r a c t e r i s t i c s , a s d e f i n e d by t h e t w e n t y p a r a m e t e r s r o u t i n e l y m e a s u r e d , have b e e n a s s e m b l e d i n Appendix 111 i n t h e s e a s o n a l s e t s of November 1

-

March 3 1 and A p r i l 1

-

O c t o b e r 31. The f i r s t of t h e w i n t e r sets r e p r e s e n t s o n l y a

t h r e e month p e r i o d of J a n u a r y , F e b r u a r y , and March s i n c e t h e s a m p l i n g program a t t h e s e p a r t i c u l a r s t a t i o n s was i n i t i a t e d J a n u a r y 1, 1 9 7 1 .

I f , a s a c c o r d i n g t o t h e p r e v i o u s a n a l y s i s t h a t showed a g e n e r a l i n c r e a s e i n r i v e r f l o w s u b s e q u e n t t o 1 9 7 0 ( T a b l e 7 ) , i t c o u l d b e assumed t h a t t h e r a i n f a l l p a t t e r n s t h a t a f f e c t e d t h e main rivers a l s o changed t h e f l o w i n t h e l a t e r a l s t r e a m s , t h e n t h e s a m p l e s from t h e l a t e r a l streams i n t h e s e t h r e e y e a r s , 1970-1973, were t a k e n u n d e r t h e same g e n e r a l r u n o f f c o n d i t i o n s . The means of t h e monthly a v e r a g e d f l o w a t S t a t i o n Haw 6 ( T a b l e 9) f o r t h e t h r e e

summer s e t s e x h i b i t a v a r i a t i o n a r o u n d t h e i r mean v a l u e of l e s s t h a n

4%.

Whereas t h e two i n i t i a l w i n t e r p e r i o d s w e r e q u i t e c o m p a r a b l e , t h e l a s t was somewhat w e t t e r t h a n e x p e c t e d . To p r o v i d e a b a s i s of c o m p a r i s o n , a l l w i n t e r w a t e r q u a l i t y v a l u e s a t e a c h s t a t i o n and a l l summer v a l u e s a t e a c h s t a t i o n h a v e been a v e r a g e d and p r e s e n t e d i n T a b l e 1 0 . T h i s i n c l u d e s t h e s i x l a t e r a l streams

and t h e r i v e r s t a t i o n Haw 6 . T h i s t a b l e of t h r e e - y e a r a v e r a g e s p e r m i t s a n e v a l u a t i o n o f t h e e x p e c t e d normal q u a l i t y of w a t e r d r a i n i n g f r o m n o n - p o i n t s o u r c e s a s compared t o t h e q u a l i t y of t h e main r i v e r below t h e j u n c t u r e w i t h t h e New Hope R i v e r .

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T a b l e 9

Monthly Average Flow S t a t i o n Haw 6

Month Nov

.

Dec

.

J a n . Feb. March

Mean

A p r i l May

J u n e J u l y Aug

.

S e p t

.

O c t .

Mean

-

Year

-

197 0

Year

-

c f s

197 1 1 5 6 1

1 3 9 8

197 2 1 6 6 3

3447

1 0 2 4

Year

-

c f s

1 9 7 2 3128

4 3 5 9

1 9 7 3 2969

4 3 3 6

(35)

T a b l e 1 0

Seasonal Averages of Water Q u a l i t y P a r a m e t e r s f o r T h r e e C o n s e c u t i v e Years (Nov. 1970-Oct. 1973)

Lower Haw R i v e r - L a t e r a l (Control). Streams* and R i v e r S t a t i o n Haw-6

Winter (Nov

.

-March)

Haw S t a t i o n s 7 9 11

P

Parameter

Temperature OC 6.9 6.3 5.9

Residue mg/l 1 0 . 1 9.5 9.9

T u r b i d i t y J T U n i t s 32.5 27.0 28.3

C o n d u c t i v i t y umhos 81.9 68.4 72.4

DO mg/l 1 1 . 5 1 0 . 9 11.2

DO % S a t u r a t i o n 94.0 8 7 . 3 88.7

BOD5 mg/l 1 . 6 1 . 6 1 . 3

T o t a l Carbon m g / l 9.9 1 0 . 3 1 0 . 2

T o t a l S o l u b l e Carbon mg/l 8 . 2 10.2 9 . 8

T o t a l I n o r g a n i c Carbon mg/l 2.6 2 . 1 3.4

T o t a l N i t r o g e n mg/l 0.70 0.56 0.35

K j e l d a h l N i t r o g e n mg/l 0.23 0.25 0.17

NH3-N mg/l 0.06 0.06 0.07

N02+N03-N mg/l 0.47 0.30 0.18

T o t a l Phosphorus mg/l 0.08 0.06 0.06

PO4-P mg/l 0.020 0.023 0.021

Summer (Apr il-Oc t

.

)

7 9 11

---

Winter (Nov

.

-March)

8 1 0 1 2

--

-

Summer (Apr il-Oc t

.

) Winter

8 1 0 12

--- 6

C h l o r o p h y l l - K l e t t U n i t s 3 . 1 2 . 1 2.4 3 . 5 3.4 3 . 1 3 . 0 2.6 3 . 2 3.3 4.3 3 . 5 3.7 9 . 9

T o t a l C o l i f o r m s No./ml 1 9 . 3 13.9 10.9 4 2 . 3 1 3 . 5 1 0 . 9 36.6 23.3 1 6 . 2 68.3 52.0 25.0 174.0 25.0

E n t e r o c o c c i No. / m l 9 . 9 2.7 2.9 1 5 . 2 6.7 7.4 1 1 . 6 13.3 3.6 17.4 1 8 . 3 1 2 . 0 9.5 5.5

*7 - Cane Creek - N.E.

9 - C o l l i n s C r e e k 11

-

F e r r e l l C r e e k

8

-

Cane C r e e k

-

West