STRATEGIES FOR WATER QUALITY MONITORING

STRATEGIES FOR WATER QUALITY MONITORING

Jabbar K. Shemani

Department of Environmental Sciences and Engineering and

David H. Moreau

Department of City and Regional Planning and

Department of Environmental Sciences and Engineering University of North Carolina at Chapel Hill

The work upon which this publication is based was supported in part by funds provided by the Office of Water Research and Technology, Depart- ment of the Interior, through the Water Resources Research Institute of The University of North Carolina as authorized under the Water Resources Research Act of 1964, as amended,

Project

No,

A-065-NC Agreement No, 14-31-0001-4033

June

1935

E.S.E, Pub, No, 398

ACKNOWLEDGMENTS

The a u t h o r s a r e i n d e b t e d t o s e v e r a l p e r s o n s f o r t h e a i d p r o v i d e d i n c a r r y i n g o u t t h i s i n v e s t i g a t i o n . Robert A, Berndt r e n d e r e d v a l u a b l e a s s i s t a n c e i n a l l a s p e c t s of t h e s t u d y , p a r t i c u l a r l y w i t h t h e p r e c e s s i n g and a n a l y s i s of d a t a . The c a l i b r a t i o n of d i s s o l v e d oxygen model f o r t h e Haw R i v e r i s based on t h e work of Tom ICnoche. P r o f e s s o r C h a r l e s M, Weiss was g r a c i o u s i n making a v a i l a b l e h i s d a t a d e c k s on t h e lower Haw and New Hope R i v e r s , The d i s c u s s i o n s a t t h e m e e t i n g s of t h e Ad

--

Hoc Working Group on Monitoring have been v e r y h e l p f u l ,

We a r e i n d e b t e d t o P r o f e s s o r David

H,

Howelhs f o r h i s c o n s t a n t g u i d a n c e , encouragement and s u p p o r t i n a l l p h a s e s of t h e s t u d y , and f o r h i s c r i t i c a l and p e r c e p t i v e review o f a n e a r l i e r d r a f t of t h i s r e p o r t , His p a t i e n c e w i t h t h e i n v e s t i g a t o r s i n t h e f a c e of r e p e a t e d d e l a y s h a s been monumental,

ABSTRACT

This study provides general guidelines for the preliminary design of a water quality monitoring system. The design is defined as the specification of the parameters to be determined, the number and Location of sampling stations, and the frequency of sampling, The role of several objecrives in the determination of monitoring strategy is considered, The objectives examined are the characteri- zation of stream water quality, enforcement of stream standards and the detection of long-term trends, Principal component analysis is used to identify important water quality parameters and to find the appropriate size of a monitoring network, Information content defined as the reciprocal of the variance of the estimate of the mean concentration is suggested as a valid criterion for the design of a monitoring network for the characterization of water quality, Impact index based

on the probability, severity and frequency of violation, number of direct users

of the stream water, predominant use and the size of stream is proposed for

determining the priority of location in an enforcement network, A protocol for

the sampling of non-point sources is presented, The Research Triangle area in

North Carolina is used as a case study, A possible framework for the strategy

of water quality monitoring is described, This consists of an initial one-time

baseline data collection program and eventually three types of networks:

_{( a )}

an

extensive network at relatively large number of key points, (b) an intensive

network in selected drainage sub-basins, and (c) a regulation network,

TABLE OF CONTENTS ( c o n t i n u e d )

P a g e

. . .

3 . 8 S a m p l e S i z e 44

. . .

3 . 9 S e a s o n a l V a r i a t i o n o f P a r a m e t e r s 45

. . .

3.10 V a r i a b i l i t y of P a r a m e t e r s 46

3 . 1 1 I n f o r m a t i o n C o n t e n t

. . .

⁴⁷

. . .

3 . 1 2 S i z e o f t h e M o n i t o r i n g Program 5 1

4

.

SPATIAL DENSITY OF STATIONS

. . .

⁵⁴

. . .

4 . 1 L o c a t i o n o f Sampling S t a t i o n s 54

. . .

4 . 2 L o c a t i o n D e s i g n 56

. . .

4 . 3 Number o f Sampling S t a t i o n s 56

. . .

4.4 G r a d i e n t L o c a t i o n T e c h n i q u e 56

. . .

4 . 5 I n t e r - s t a t i o n C o r r e l a t i o n s T e c h n i q u e 57

. . .

5

.

FREQUENCYOF SAMPLING 6 1

. . .

S y s t e m D y n a m i c s 6 1

. . .

Sampling F r e q u e n c y D i s t r i b u t i o n 63

. . .

Temporal V a r i a b i l i t y o f V a r i a n c e 67

. . .

F r e q u e n c y D e s i g n 68

. . .

Type o f P a r a m e t e r 69

. . .

S t a t i s t i c a l R e q u i r e m e n t s 69

. . .

A v e r a g i n g I n t e r v a l 70

. . .

S e r i a l C o r r e l a t i o n and P e r i o d i c i t y 7 1

. . .

E m p i r i c a l P r o c e d u r e f o r Sampling F r e q u e n c y 72

6

.

VIOLATION DETECTION NETWORK

. . .

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

. . .

Review o f P r e v i o u s S t u d i e s

. . . . . . .

Ward's Approach

. . .

R a y t h e s n Approach

C r i t i q u e o f t h e P r o p o s e d Approaches P r o b a b i l i t y of V i o l a t i o n

. . .

L o c a t i o n s of Sampling S t a t i o n s

.

M a t h e m a t i c a l Modeling

. . .

Segment P r i o r i t y Ranking

. . .

F r e q u e n c y of Sampling

. . .

7

.

SAMPLINGFORTREND

. . .

⁸⁶

. . .

7 . 1 Dynamic N a t u r e o f Water Q u a l i t y System 8 6

. . .

7 . 2 D e c o m p o s i t i o n o f a Time S e r i e s 87

. . .

7 . 3 D e s i g n o f a Trend Network 89

. . .

7.4 L e n g t h o f Record 92

. . .

8

.

NON-POINT SOURCES 94

. . .

8 . 1 I n t r o d u c t i o n 94

. . .

8 . 2 L a n d u s e a n d w a t e r Q u a l i t y 94

. . .

8 . 3 Comparison o f Man-made and N a t u r a l S o u r c e s 95

. . .

8 . 4 R e c u r r i n g Storm E v e n t s 97

. . .

8 . 5 S i g n i f i c a n c e of Non-point S o u r c e s 98

TABLE OF CONTENTS (continued)

Page

. . .

8.6 Estimates of Non-point Sources 100

. . .

8.7 Impact Analysis sf Stormwater Flows 101

. . .

8.8 Sample Surveys of Non-point Sources 102

. . .

9 . NON-POINT SOURCES: A CASE STUDY 105

Introduction . . . ¹⁰⁵ . . .

Point Sources and Loads 109

. . .

Non-point Sources 111

UrbanRunoff . . . ¹¹² . . . .

Variation of Water Quality Within Storm Events 112

. . .

RuralRunoff 113

. . .

First Estimates of Non-point Loads 114

. . .

Comparison of Point and Non-point Loads 118 Recommendations for

Improving

Estimates of Non-point Loads . ¹¹⁸

. . .

Stormwater Impact Analyses 120

. . .

Accounting for Benthic Deposits 122

. . .

10 . MONITORING STMTEGU 123

. . .

10.1 Varied Requirements of Monitoring Design

1 2 3

. . .

10.2 One-time Basic Data Program 123

. . .

10.3 Franework of Monitoring Design 124

. . .

ExtensiveNetwork 125

. . .

Regulation Network 125

. . .

Intensive Network 126

. . .

REFERENCES 127

. . .

APPENDIX 131

LIST OF TABLES

Table Title Page

. . .

Water QualityDataUses 4

Time-Phased Goals of Water Quality Monitoring in

Regulation and Control . . . ⁶

Water Quality Sampling Locations . . . ²¹ . . .

Periods of Sampling 22

Water Quality Parameters Determined in the 1966-73

Series. Lower Haw and New Hope Rivers . . . ²³ . . .

Important Parameters for Different Uses 27 Physical and Chemical Characteristics for Biological

Monitoring . . . ²⁸

Inter-Parameter Correlation. HAW.5. Summer . . . ³¹

Inter-Parameter Correlation. NH.10. Summer . . . ³²

Highest Number of Significant Inter-Parameter

Correlations. HAW.5. Summer . . . ³³

Highest Correlation Than With Any Other Parameter.

HAW-5

a . . . . . . . . . . . . . . . . . . . . . . . .

34 Variance Explained by Principal Components . . . ³⁷

. . .

Principal Components 38

. . .

Varimax Rotated Factor Matrix 39

. . .

HAW-5 Parameter Concentrations. October-April 49

. . .

HAW-5 Parameter Concentrations. May-September 49 Ranking of Parameters for Variability. HAW.5. Summer . . ⁵⁰

Ranking W.R.T. of Parameters forvariability. NH-10. Summer 50

. . .

Characteristics of Dissolved Oxygen: Haw River 58 Inter-Station Correlation Coefficients for Dissolved

Oxygen . . . ⁵⁸

Factor Matrix Using Principal Components . . . ⁵⁸

Percent of Variance Explained by Principal Components . . ⁵⁸ . . .

Varimax Rotated Factor Matrix 59

. . .

Variance vs. Network Size 59

. . .

Chi-square Goodness of Fit 64

Flow of French Broad River. Analysis of Weekly Periods . ⁶⁷

Number of Samples Required. HAW.5. Summer . . . ⁷⁰

Average Dissolved Solids Determined by Different Sampling

Frequencies. Rocky River Near Norwood. North Carolina . . ⁷²

LIST OF TABLES (continued) Table

29 3

0 3

l 3 2 3

3 34 3 5

36

3 7 3 8 3

9

4

0 41 4 2 A- 1

Title Page

Probability of Violation

* a *

-

^{* * a 0 a a a 0}

^.

⁷⁹

. . .

Determination of K1.

"2

" and Ultimate BOD 8%

Specification of Classes for Segment Priority Ranking . . ⁸⁴ . . .

Llnear Decmposition of Dissolved Solids Series 98

. . .

Variance Reduction Factor for Spatial Sampling 93

. . .

Reduction in Variance of a Network 93

. . .

Urban

and

Natural Stream Quality 96

. . .

Seasonal Variability of Parameters 96

Comparative Rates of Soil Erosion for Various Land Uses 99

. . .

Inventory of Point Sources 110

. . .

Estimated Loads from Point Sources by Watersheds 111

. . .

Waste Load Factors for Farm Animals 115

. . .

Estimates of Land Use by Watersheds 116

. . .

Estimates of Pollutant

Loads

from Nsn-Point Sources 117 Inter-Parameter Correlation Coefficients for Station

. . .

HAW.5. Whole Year 132

Inter-Parameter Correlation Coefficients for Station

. . .

MM.5.

Sumer Months 134

Inter-Parameter Correlation Coefficients of Log

. . .

Transforms for Station -fiW-5

136

LIST OF FIGURES Figure

1 2 3

Title Page

Water Quality Sampling Stations 1966-1973 . . . ¹⁹

River and Stream Distances, Miles . .

^{* a}

.

^{* 20}

Histogram for Total Coliforms for Station

H - 1

on

the Haw River. . . . ⁶⁵

Histogram for Dissolved Oxygen for Station H-1 on

the Haw River . . . ⁶⁶

Histogram for Summer Values of Dissolved Oxygen

. . .

for Station H-1 on the Haw River 66

Monthly Streamflow Statistics at Selected Gaging

. . .

Stations . . I 0 7

Flow-Duration Curve for Daily Flows at Selected

. . .

Gaging Stations 108

viii

SUMMARY, CONCLUSIONS AND RECOMNENDATIONS

T h i s s t u d y d e a l s w i t h t h e m o n i t o r i n g of s t r e a m p o r t i o n s o f t h e d r a i n a g e b a s i n s . It p r o v i d e s g e n e r a l g u i d e l i n e s f c r t h e d e s i g n of water q u a l i t y mani- t o r i n g s y s t e m s . To make t h e t a s k of m o n i t o r i n g manageable u n d e r c o n s t r a i n t s of f i n a n c i n g and manpower, t h e a s s u m p t i o n i s made t h a t t h e r e i s a minimum flaw r e q u i r e m e n t f o r t h e stream t o b e i n c l u d e d i n t h e n e t w o r k , I n t e r m i t t e n t s t r e a m s a r e e x c l u d e d b e c a u s e t h e y r e q u i r e s p e c i a l t r e a t m e n t . The c o n s i d e r a t i o n s o f c o s t , r e l i a b i l i t y , a n d m a i n t e n a n c e are n o t i n c l u d e d b e c a u s e o f l a c k of d a t a . D a t a t r a n s m i s s i o n and h a n d l i n g was o u t s i d e t h e s c o p e o f t h i s s t u d y .

The d e s i g n of a m o n i t o r i n g n e t w o r k i s d e f i n e d a s t h e s p e c i f i c a t i o n of t h e number a n d l o c a t i o n of s a m p l i n g s i t e s , f r e q u e n c y o f s a m p l i n g , a n d t h e p a r a m e t e r s

t o b e measured.

The f i r s t r e q u i r e m e n t of d e s i g n i n g a m o n i t o r i n g n e t w o r k i s a n e x p l i c i t s t a t e m e n t o f o b j e c t i v e s , S e v e r a l o b j e c t i v e s were examined, a n d i t i s c o n c l u d e d t h a t t h e r e i s n o s i n g l e s p e c i f i c a t i o n of a n e t w o r k which i s o p t i m a l f o r a l l p u r p o s e s ,

I n a d d i t i o n t o c o n c e n t r a t i o n s , a knowledge of mass f l o w o f p o l l u t a n t s i s e s s e n t i a l t o u n d e r s t a n d t h e w a t e r q u a l i t y b e h a v i o r o f a s t r e a m s y s t e m , T h e r e - f o r e , m o n i t o r i n g s t a t i o n s s h o u l d o n l y b e a t s i t e s where f l o w s can b e e s t i m a t e d w i t h some d e g r e e o f a c c u r a c y .

The v i o l a t i o n o f stream s t a n d a r d s a r i s i n g from a c c i d e n t a l o r i n t e n t i o n a l s p i l l s c a n n o t b e d e a l t w i t h e c o n o m i c a l l y by a m o n i t o r i n g n e t w o r k a n d s h o u l d n o t i n f l u e n c e i t s d e s i g n .

I n t e r - p a r a m e t e r c o r r e l a t i o n s t u d i e s on t h e New Hope and Haw R i v e r s show t h a t i n g e n e r a l t h e s e c o r r e l a t i o n s a r e n o t s t r o n g o r w i d e s p r e a d . T h e r e f o r e , economy i n t h e number o f p a r a m e t e r s t o b e sampled a t a s i t e i s g e n e r a l l y n o t p o s s i b l e .

The m o n i t o r i n g o f t o x i c a n d h a z a r d o u s s u b s t a n c e s h a s i t s own s p e c i a l r e q u i r e m e n t s . I t s h a l l h a v e t o c o n s i d e r mass f l o w s i n a l l components of t h e s t r e a m i n o r d e r t o a r r i v e a t a n a d e q u a t e m a t e r i a l s b a l a n c e f o r e a c h s o u r c e , The g e n e r a l m o n i t o r i n g n e t w o r k can p r o v i d e o n l y l i m i t e d s u p p o r t i n t h a t e n d e a v o r .

The c o l i f o r m g r o u p p r e s e n t s s p e c i a l p r o b l e m s i n t h e d e s i g n o f a m o n i t o r i n g n e t w o r k . I t g i v e s r e s u l t s

that

are s o d i s c o r d a n t a s compared t o o t h e r p a r a m e t e r s

t h a t i t s c o n s i d e r a t i o n s h o u l d b e dropped i n d e s i g n i n g a m o n i t o r i n g n e t w o r k ,

A u n i q u e method f o r a r r i v i n g a t t h e s p a t i a l d e n s i t y o f a n e t w o r k u s i n g p r i n c i p a l components and i n t e r - s t a t i o n c o r r e l a t i o n i s p r e s e n t e d .

The a s s u m p t i o n i s u s u a l l y made t h a t t h e q u a l i t y p a r a m e t e r s f o l l o w a n o r m a l d i s t r i b u t i o n . F o r a m a j o r i t y of c o n s t i t u e n t s t h i s i s n o t a v a l i d a s s u m p t i o n . Log-normal and gamma d i s t r i b u t i o n s p r o v i d e a b e t t e r f i t and s h o u l d b e u s e d f o r c a l c u l a t i n g t h e p r o b a b i l i t y o f v i o l a t i o n .

F o r most o f t h e p a r a m e t e r s t h e r e i s s i g n i f i c a n t s e a s o n a l d i f f e r e n c e i n t h e i r b e h a v i o r , Assumption o f s t a t i o n a r i t y i s o n l y v a l i d i f t h e y e a r i s d i v i d e d i n t o two p e r i o d s : May t o September a n d O c t o b e r t o A p r i l .

T h e r e i s n o s i n g l e p e r i o d o f t h e y e a r which g i v e s c r i t i c a l c o n d i t i o n s w i t h r e s p e c t t o a l l t h e p a r a m e t e r s and can b e t a k e n a s t h e b a s e p e r i o d of d e s i g n ,

The v a r i a n c e o f d i f f e r e n t p a r a m e t e r s h a s d i f f e r e n t v a l u e s a t d i f f e r e n t t i m e s o f t h e y e a r . F o r t h e same i n f o r m a t i o n c o n t e n t , t h e f r e q u e n c y o f s a m p l i n g c o u l d b e v a r i e d a t d i f f e r e n t t i m e s o f t h e y e a r . T h e r e i s n o s i n g l e f r e q u e n c y which i s o p t i m a l f o r a l l t h e p a r a m e t e r s .

I n f o r m a t i o n c o n t e n t d e f i n e d by t h e r e c i p r o c a l of t h e v a r i a n c e of t h e e s t i - mate of t h e mean p r o v i d e s a v a l i d c r i t e r i o n f o r t h e d e s i g n . T h i s h a s n o t b e e n

s u g g e s t e d as a d e s i g n c r i t e r i o n f o r w a t e r q u a l i t y m o n i t o r i n g b e f o r e .

The d e t e c t i o n of a c e r t a i n p e r c e n t a g e of t e c h n i c a l v i o l a t i o n s of w a t e r q u a l i t y s t a n d a r d s h a s been a d v o c a t e d as t h e d e s i g n c r i t e r i o n , T h i s i s an i n a d e q u a t e c r i t e r i o n . I t i s s u g g e s t e d t h a t t h e p o t e n t i a l i m p a c t o f a v i o l a - t i o n should also b e c o n s i d e r e d , An i m p a c t i n d e x i s p r o p o s e d f o r d e c i d i n g t h e p r i o r i t y of a l o c a t i o n . The i n d e x s h o u l d b e b a s e d on t h e p r o b a b i l i t y o f v i o l a - t i o n o f t h e s t a n d a r d , number of d i r e c t u s e r s of t h e s t r e a m w a t e r , s i z e o f t h e s t r e a m and t h e p r e d o m i n a n t e x i s t i n g o r p l a n n e d u s e of t h e stream.

To d e t e r m i n e c a n d i d a t e l o c a t i o n i n a c r i t i c a l s t r e a m s e g m e n t , d i s t i n c t i o n h a s t o b e made between c o n s e r v a t i v e , n o n - 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 c o u p l e d c o n s t i t u e n t s .

An a n a l y s i s of S t r e e t e r - P h e l p s e q u a t i o n on a segment o f t h e Haw R i v e r i n d i c a t e d t h a t t h e e s t i m a t i o n o f d e o x y g e n a t i o n c o n s t a n t v a l u e s o b t a i n e d from BOD d a t a w e r e p o o r , The s i m u l t a n e o u s l e a s t s q u a r e e s t i m a t i o n of kl a n d k2

from DO d a t a a l o n e g a v e a v e r y good f i t . The u s e f u l n e s s o f BOD d a t a as a d e t e r m i n a n t o f stream w a t e r q u a l i t y i s q u e s t i o n a b l e , An i m p o r t a n t v a r i a b l e i s t h e t i m e of t r a v e l which s h o u l d b e o b s e r v e d whenever p o s s i b l e .

The design of a monitoring network based on point sources alone can provide only partial answers. The consideration of storm water runoff is essential to determine critical conditions. It is suggested that mobile sampling may be advantageous in this case,

In order to extend the useful range of models developed during intensive surveys, the effect of the variation of flows and temperatures on the time of travel, reaction kinetics, and sedimentation rates should be determined,

Field estimates of non-point source loads and related runoff coefficients should be developed for storm events of different frequencies and magnitudes on selected rural and urban watersheds representing various types of land uses,

It is concluded that with the lack of actual data it is not possible to give a p m h i a reasonably good estimate of the required density and sanpling frequency of a monitoring network on the basis of analytical considerations alone. An intensive effort one-year program to collect monthly samples at apprsximately 1000 locations, providing adequate coverage of representative conditions throughout North Carolina, should be instituted,

The final network should have three components: (1) an extensive network at a relatively large number of keypoints sampled at longer intervals for a relatively large number of parameters, (2) a regulation network compatible with the self-monitoring of sources with locations

at

extreme values of constituents, and (3) an intensive network, oversampled initially, for a complete and detailed picture of water quality in selected drainage sub-basins,

The sampling for non-point sources should be arrived at on the basis of

stratified random sampling.

C h a p t e r 1 INTRODUCTION 1,l O b j e c t i v e s o f t h e Study

The p u r p o s e s o f t h i s r e p o r t a r e t o p r o v i d e g e n e r a l g u i d e l i n e s f o r t h e d e s i g n of m o n i t o r i n g systems f o r s t a t e w a t e r q u a l i t y management and t o p r e s e n t t h e f i n d i n g of i n v e s t i g a t i o n s i n t o s e l e c t e d s p e c i f i c a s p e c t s of t h a t d e s i g n problem i n North C a r o l i n a , P a r t i c u l a r a t t e n t i o n i s g i v e n t o t h e p u r p o s e s and t y p e s o f d a t a n e e d s , t h e f r e q u e n c y , d u r a t i o n , s p a t i a l d i s t r i b u t i o n , and p a r a - m e t r i c c o v e r a g e of ambient w a t e r q u a l i t y , A n a l y t i c a l methods and r e s u l t s o f

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

l o a d s , i n c l u d i n g p r e l i m i n a r y r e s u l t s f o r t h e Research T r i a n g l e a r e a , i s d i s - c u s s e d , R e l a t e d a s p e c t s of m o n i t o r i n g , i n c l u d i n g measurement t e c h n i q u e s , d a t a s t o r a g e , r e t r i e v a l , and a n a l y s i s a r e beyond t h e scope o f t h e r e p o r t ,

Remaining p o r t i o n s of C h a p t e r 1 c o v e r t h e f a c t o r s i n f l u e n c i n g w a t e r q u a l i t y i n North C a r o l i n a , t h e need f o r w a t e r q u a l i t y i n f o r m a t i o n , t h e t y p e s o f d a t a r e q u i r e d , and g e n e r a l p r i n c i p l e s and c r i t e r i a t o be c o n s i d e r e d i n t h e d e s i g n of m o n i t o r i n g n e t w o r k s , C h a p t e r 2 c o n t a i n s a n e x a m i n a t i o n of t h e r a n g e of p a r a m e t e r s n e c e s s a r y t o d e f i n e w a t e r q u a l i t y and a n a l y s e s of i n t e r - p a r a m e t r i c r e l a t i o n s h i p s t h a t c o u l d l e a d t o economies i n t h e number o f p a r a - m e t e r s t o be sampled, Chapter 3 c o n s i d e r s t h e t e m p o r a l v a r i a b i l i t y of w a t e r q u a l i t y p a r a m e t e r s a t f i x e d l o c a t i o n s , t h e i m p l i c a t i o n s of t h a t v a r i a b i l i t y on t h e number of samples r e q u i r e d , and i t s i n f l u e n c e on t h e i n f o r m a t i o n that c a n be g a i n e d from samples a t n e i g h b o r i n g l o c a t i o n s , A n a l y s e s of r e q u i r e d s p a t i a l d e n s i t i e s f o r sampling s t a t i o n s a r e r e p o r t e d i n C h a p t e r 4 , and

C h a p t e r 5 c o n r a i n s a d i s c u s s i o n and e m p i r i c a l r e s u l t s r e l a t e d t o t h e f r e q u e n c y a n d a v e r a g i n g i n t e r v a l s f o r sampling, S p e c i a l c o n s i d e r a t i o n s f o r t h e d e s i g n of s u r v e i l l a n c e networks t o d e t e c t v i o l a t i o n s s f w a t e r q u a l i t y s t a n d a r d s a r e g i v e n i n C h a p t e r 6 ; sampling f o r t r e n d s and e s t i m a t i o n o f components i n t r e n d models a r e d i s c u s s e d i n C h a p t e r 7, E s t i m a t i o n of n o n - p o i n t s o u r c e s i s t r e a t e d i n Chapter 8 , and a c a s e s t u d y of t h e amounts, s o u r c e s , and

r e l a t i v e importance o f n o n - p o i n t l o a d s i s p r e s e n t e d i n C h a p t e r 9 , Concluding remarks on a g e n e r a l s t r a t e g y f o r m o n i t o r i n g a r e c o n t a i n e d i n Chapter P O ,

% , 2 F a c t o r s A f f e c t i n g Water Q u a l i t y i n North C a r o l i n a

M o n i t o r i n g systems f o r w a t e r q u a l i t y and i t s c o n t r o l i n v o l v e h i g h l y s p e c i f i c d a t a on s o u r c e s of p o l l u t i o n and l e v e l s o f q u a l i t y i n p a r t i c u l a r segments of s t r e a m s , General i n f o r m a t i o n a b o u t s o u r c e s , c h a r a c t e r i s t i c s of s t r e a m s , and q u a l i t y l e v e l s i s o f l i t t l e v a l u e i n t h e d e s i g n and o p e r a t i o n of w a t e r q u a l i t y c o n t r o l s , However, a g e n e r a l u n d e r s t a n d i n g of t h e s p a t i a l d i s t r i b u t i o n s and amount o f human a c t i v i t y and n a t u r a l f o r c e s t h a t a f f e c t p o l l u t i o n l o a d s and t h e i r p o t e n t i a l i m p a c t s on w a t e r q u a l i t y i s e s s e n t i a l t o t h e s e a r c h f o r

p o s s i b l e and p r o b a b l e w a t e r q u a l i t y problems, General i n f o r m a t i o n i s r e q u i r e d a b o u t t h e p h y s i o g r a p h y , m e t e o r o l o g y , hydrology, geology, and t h e u s e s t o which t h e l a n d r e s o u r c e i s p u t , Data on t h e s e f a c t o r s would b e i n c l u d e d w i t h i n a broad d e f i n i t i o n o f w a t e r q u a l i t y m o n i t o r i n g , a n d , a l t h o u g h a more r e s t r i c t i v e d e f i n i t i o n of t h e t e r m i s u s e d i n t h i s r e p o r t , u p - t o - d a t e i n f o r m a t i o n on t h e s e r e l a t e d f a c t o r s i s assumed t o b e a p a r t of t h e s t o r e h o u s e of i n f o r m a t i o n on w a t e r q u a l i t y ,

Sone of t h e most s i g n i f i c a n t i n f l u e n c e s on d i f f e r e n c e s i n w a t e r q u a l i t y a c r o s s North C a r o l i n a a r e n a t u r a l d i f f e r e n c e s among t h e t h r e e p h y s i o g r a p h i c r e g i o n s o f t h e s t a t e , s p a t i a l v a r i a t i o n s i n t h e l e v e l s of u r b a n i z a t i o n and a g r i c u l t u r a l p r o d u c t i o n , and v a r i a t i o n s i n t h e k i n d s and i n t e n s i t i e s of i n - d u s t r i a l development, The Blue Ridge and Piedmont Regions a r e u n d e r l a i n by h a r d c r y s t a l l i n e r o c k s , w h i l e t h e C o a s t a l P l a i l l h a s more s o l u b l e c l a y s , s a n d s , m a r l s , and l i m e s t o n e s , Thus, s t r e a m s i n t h e Blue Ridge and Piedmont P r o v i n c e s a r e lower i n m i n e r a l c o n t e n t t h a n t h o s e o f t h e C o a s t a l P l a i n s . F u r t h e r m o r e , b e c a u s e s t r e a m s i n C o a s t a l P l a i n s c o n t a i n d r a i n a g e from a l l t h r e e p r o v i n c e s , a n d , t h e r e f o r e , t h e y t e n d t o a c c u m u l a t e , up t o t h e l e v e l of s a t u r a t i o n , a l l c o n t r i b u t i o n s from u p s t r e a m s o u r c e s . Seawater i n t r u s i o n i n t h e lower r e a c h e s of e s t u a r i e s a d v e r s e l y a f f e c t s t h e chemical q u a l i t y o f t h o s e w a t e r s and r e n d e r s them u n f i t f o r many p u r p o s e s , The e x t e n t of s a l t - w a t e r encroachment and r e l a t e d w a t e r q u a l i t y v a r y w i t h t h e a c t i o n of winds and t i d e s and w i t h t h e magnitude of f r e s h w a t e r r u n o f f , I n p e r i o d s of low f r e s h w a t e r f l o w , h i g h c h l o r i d e c o n c e n t r a t i o n s move i n l a n d ; i n p e r i o d s of h i g h f l o w , t h e y move downstream.

A g r i c u l t u r a l i n f l u e n c e s on w a t e r q u a l i t y a r e a l s o s i g n i f i c a n t , More t h a n h a l f of North C a r o l i n a p o p u l a t i o n r e s i d e s i n r u r a l a r e a s , and much o f t h e economy o f t h e s t a t e r e t a i n s a n a g r i c u l t u r a l b a s e , Watersheds o f t h e s t a t e c o n s i s t m o s t l y of f o r e s t l a n d s , p a s t u r e l a n d s , and l a n d s i n row c r o p s .

These l a n d s y i e l d s u b s t a n t i a l amounts o f sediment, p e s t i c i d e s and f e r t i l i z e r s , and o r g a n i c m a t t e r from a n i m a l - p r o d u c t i o n o p e r a t i o n s (mainly p o u l t r y , hogs, and d a i r y c a . t t l e ) . Drainage s f swamp l a n d s i n E a s t e r n North C a r o l i n a r a i s e s t h e p o t e n t i a l o f s i g n i f i c a n t changes i n b o t h t h e q u a n t i t y and q u a l i t y of s t r e s m f l o w s , Although r e t u r n f l o w s from s u p p l e m e n t a l i r r i g a t i o n have been r e l a t i v e l y minor, t h e u s e of i r r i g a t i o n i s growing and t h e i n t r o d u c t i o n o f l a r g e a g r i - b u s i n e s s o p e r a t i o n s c o u l d have f a r r e a c h i n g consequences on w a t e r q u a l i t y ,

P r o b a b l y t h e g r e a t e s t i n f l u e n c e i n w a t e r q u a l i t y h a s been u r b a n i z a t i o n and r e l a t e d i n d u s t r i a l a c t i v i t i e s , Although a r e l a t i v e l y s m a l l p e r c e n t a g e o f t h e l a n d i n North C a r o l i n a i s u r b a n , t h e c s n e e n t r a t i s n o f a c t i v i t i e s a n d t h e i r w a s t e p r o d u c t s i n t h e s e c e n t e r s l e a d t o profound changes i n w a t e r q u a l i t y i n s t r e a m s t h a t d r a i n w a t e r s h e d s on which t h e c i t i e s a r e l o c a t e d , The s p a t i a l d i s t r i b u t i o n o f u r b a n a c t i v i t i e s i n t h e s t a t e f u r t h e r a g g r a v a t e s t h e problem, f o r much o f t h e p o p u l a t i o n i s l o c a t e d i n t h e Piedmont P r o v i n c e where s t r e a m a r e much s m a l l e r t h a n i n t h e C o a s t a l P l a i n , I n a d d i t i o n t o t h e r e a d i l y i d e n t i - f i e d p o i n t s o u r c e s o f p o l l u t i o n from m u n i c i p a l sewerage systems and I n d u s t r i a l w a s t e , d i f f u s e l o a d s from u r b a n l a n d s t h a t a r e t r a n s p o r t e d by s t o m w a t e r r u n o f f c o n t r i b u t e s u b s t a n t i a l amounts of p o l l u t a n t s t o s t r e a m s of t h e s t a t e , Impacts from u r b a n s t o r m r u n o f f a r e p a r t i c u l a r l y significant d u r i n g p e r i o d s i n which b a s e f l o w s i n s t r e a m s a r e s m a l l ,

l , 3 The Need f o r Water Q u a l i t y Data

A l l p h a s e s o f p l a n n i n g , development, and o p e r a t i o n o f a w a t e r r e s o u r c e management system, i n c l u d i n g w a t e r q u a l i t y c o n t r o l , r e q u i r e t h e a c q u i s i r i o n and p r o c e s s i n g of d a t a t o q u a n t i f y e x i s t i n g s t a t e s o f t h e system, t o f o r e c a s t f u t u r e changes and t r e n d s , and t o p r e d i c t r e s p o n s e s o f the s y s t e m t o inter- v e n t i o n s f o r development and c o n t r o l , The k i n d o f d a t a r e q u i r e d and t h e i r s p a t i a l and t e m p o r a l r e s o l u t i o n depend upon n a t u r e o f t h e problems and k i n d s o f i n t e r v e n t i o n s under c o n s i d e r a t i o n , The word m o n i t o r i n g h a s been d e f i n e d a s t h i s a c t i v i t y o f making " s y s t e m a t i c o b s e r v a t i o n s o f p a r a m e t e r s r e l a t e d t o a s p e c i f i c problem, d e s i g n e d t o p r o v i d e i n f o r m a t i o n o n t h e c h a r a c t e r i s t i c s of t h e problem and t h e i r changes w i t h t i m e " ( l ) ,

A p a r t i a l l i s t of n e e d s and u s e s f o r w a t e r q u a l i t y d a t a 5s shown i n T a b l e

1,

C o n s t r u c t i o n o f e x h a u s t i v e l i s t of uses would b e i m p o s s i b l e , and i t f o l l o w s t h a t a l l p o s s i b l e u s e s of t h e d a t a and t h e i r most c o n v e n i e n t format c a n n o t b e a n t i c i p a t e d p r i o r t o t h e d e s i g n of a m o n i t o r i n g network, Even i f a l l p o s s i b l e u s e s c o u l d be f o r e s e e n , t h e number of u s e z would be s o

T a b l e 1

IdATER QUALITY

DATA USES

R e c e p t o r User R e q u i r e m e n t s

-

P u b l i c I n t e r e s t :

-

P l a n n i n g :

Pub l i e H e a l t h A e s t h e t i c s N u i s a n c e

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

N a t u r a l s t a t e p r e s e r v a t i o n R e c r e a t i o n

W a t e r and r e l a t e d l a n d u s e p l a n n i n g Economic p l a n n i n g

Urban p l a n n i n g

-

R e g u l a t i o n a n d C o n t r o l : I d e n t i f i c a t i o n of S o u r c e s F a t e o f P o l l u t a n t s

D e s c r i p t i o n of p r e s e n t s t a t e o f q u a l i t y

P r e d i c t i o n of w a t e r q u a l i t y E v a l u a t i o n o f t r e n d s

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

Measurement of p r o g r e s s i n p o l l u t i o n ab a t e n e n t E p i s o d i c e f f e c t s

N o n - d e g r a d a t i o n p o l i c y R e search

L e g i s l a t i o n P u b l i c h e a r i n g s

U s e r - o r i e n t e d r e p o r t s

-

^Data I n t e r c h a n g e :

l a r g e and v a r i e d i n format t h a t i t would n o t be p o s s i b l e t o d e s i g n a s i n g l e network t h a t would e c o n o m i c a l l y s a t i s f y a l l p u r p o s e s , A r e a s o n a b l e s t r a t e g y i n t h i s s i t u - a t i o n i s t o i d e n t i f y t h e p r i m a r y d a t a n e e d s , develop t h e d e s i g n around t h o s e n e e d s , t e s t t h e system f o r s e c o n d a r y u s e s , and modify t h e d e s i g n i f p o s s i b l e t o accommodate t h e l a t t e r u s e s .

There would a p p e a r t o be t h r e e m a j o r c a t e g o r i e s of a c t i v i t i e s i n s t a t e w a t e r r e s o u r c e management f o r which w a t e r q u a l i t y d a t a i s e s s e n t i a l , They a r e : ( 1 ) p l a n n i n g , e v a l u a t i o n , and enforcement of w a t e r q u a l i t y c o n t r o l p o l i c i e s and f a c i l i t i e s ; (2) g e n e r a l w a t e r r e s o u r c e p l a n n i n g ; and ( 3 ) r e s e a r c h t o g a i n a n improved u n d e r s t a n d i n g of t h e n a t u r e of w a t e r r e s o u r c e s y s t e m s , e s p e c i a l l y t h e q u a l i t y a s p e c t s o f t h o s e systems,

E.3,I Water Q u a l i t y Management, A t p r e s e n t , t h e most s i g n i f i c a n t w a t e r r e s o u r c e problem t o which t h e S t a t e of North C a r o l i n a i s a d d r e s s i n g i t s e l f i s t h e p r o t e c t i o n and enhancement of w a t e r q u a l i t y l e v e l s i n t h e r i v e r s , r e s e r v o i r s , l a k e s , and e s t u a r i e s , I n s e a r c h of a w a t e r q u a l i t y management program t h a t imposes t h e l e a s t demand on m a t e r i a l r e s o u r c e s and t h e h e a l t h and s a f e t y of s o c i e t y , t h e s t a t e must p e r f o r m s e v e r a l f u n c t i o n s , Ward (2) l i s t s seven b a s i c d u t i e s : ( 1 ) p l a n n i n g , ( 2 ) r e s e a r c h , ( 3 ) a i d programs, (4) t e c h n i c a l a s s i s t a n c e , ( 5 ) r e g u - l a t i o n , ( 6 ) l e g a l e n f o r c e m e n t , and ( 7 ) d a t a c o l l e c t i o n , p r o c e s s i n g , and d i s - s e m i n a t i o n , These can be grouped i n t o two broad c a t e g o r i e s : p r e v e n t i o n and abatement. The p r e v e n t i o n o b j e c t i v e i s r e l a t e d t o m a i n t a i n i n g t h e e x i s t i n g good w a t e r q u a l i t y , w h i l e abatement r e f e r s t o r e d u c i n g o r m o d e r a t i n g e x i s t i n g p o l l u t i o n c o n d i t i o n s , The d a t a c o l l e c t i o n , and p r o c e s s i n g p r o v i d e s u p p o r t i n a l l t h e s e f u n c t i o n s ,

S e v e r a l t a s k s , i n c l u d i n g t h o s e t h a t c o n t r i b u t e t o s h o r t - t e r m , i n t e r - m e d i a t e , and l o n g - r a n g e g o a l s , a r e n e c e s s a r y i n t h e performance of t h o s e d u t i e s ; a p a r t i a l l i s t i n g o f t h e t a s k s i s g i v e n i n Table 2 ,

C o n t i n u i n g p l a n n i n g p r o c e s s e s g e n e r a l l y i n v o l v e p e r i o d i c r e - e x a m i n a t i o n o f b a s i c g o a l s and programs t o a c h i e v e t h o s e g o a l s a s changes i n t h e w a t e r r e s o u r c e system and s o c i e t a l v a l u e s o c c u r o v e r t i m e , L o g i c a l p r o c e d u r e s f o r t h e s e p e r i o d i c i n t e n s i v e p l a n n i n g e f f o r t s g e n e r a l l y i n c l u d e :

I , g a t h e r i n g d a t a t o d e t e r m i n e c u r r e n t s t r e a m q u a l i t y and i t s c a u s e s ;

2. s p e c i f y i n g g o a l s and p l a n n i n g o b j e c t i v e s ( u s u a l l y t o a c h i e v e w a t e r q u a l i t y s t a n d a r d s a t l e a s t c o s t ) ;

Table 2

TIME-PHASED GOALS OF WATER QUALITY MONITORING IN REGULATION AND C O N T R O L

A, Short-term Goals

1, Monitor and investigate complaints

2, Identification of gross pollution and nuisance conditions

3. Prevention of water pollution emergencies or episodes; e,g., fish kills

4 ,

Set, amend, or repeal water quality standards

5, Development of effluent standards

6,

Issuance of discharge permits for significant waste sources

7, Enforcement of existing standards; investigation of the degree of compliance and frequency of violation

8,

Establishment of priorities for the control of sources of pollution

9 ,

Authorize and approve water pollution control and abatement plans

for drainage basins

B,

Intermediate Goals

1, Determine the nature and extent of pollution in areas of interest 2, Preparation of control strategies and time-staging of program 3, Develop integrated data system to meet receptor-user requirements

4 ,

Development of water quality criteria and standards

5, Evaluation of the effectiveness of activities aimed at controlling water pollution as evidenced by general changes in water quality

C.

Long-term Goals

1. Long-range program planning, policy, and land-use planning 2. Determination of origin and distribution of pollutants 3, Tracing of pathways and fate of pollutants

4. Understanding of the physical, chemical, and biological response of streams

5. Evaluation of various control strategies

6. Response of water quality to standards, permits, regulation, and en£ orcement

7, Prediction of water quality

8, Evaluation of trends; determination of the background levels of

pollution

3, formulating water quality control strategies; and 4. evaluating the costs and effectiveness of strategies,

The absence of an adequate data base in the past to relate strategies to goals in the planning process and to evaluate strategies as they have been implemented has led to an inversion of the above logic, Primary emphasis has been placed on the strategies or means of water quality control with insufficient attention to causes of adverse water quality and cost-effective programs for alleviating it,

Once cost-effective strategies have been developed and implemented through legislation, construction of facilities, ordinances, pricing policies, etc., they must be enforced, Enforcement is a regulatory function that deals with the compliance, or non-compliance with water quality standards, effluent limitations and other rules for managing the system, Its effectiveness depends upon the ability of the regulatory agency to detect violations of the rules,

However, continuing monitoring should not be limited to just those seg- ments of streams and related sources of pollution in which violations of

rules may be anticipated, Continuing evaluation of the adequacy of existing standards and trends in the quality of water in all segments of streams sub- ject to changing influences on water quality is necessary, This continuing evaluation has several aspects: (1) to determine whether or not standards established for particular waters are providing the desired level of protec- tion for uses they were established to maintain; (2) to decide whether the existing or proposed uses are consistent with the established standards, (3) to ascertain the feasibility of achieving or maintaining the existing standards at reasonable cost, and (4) to assess the need for revising the standards up- wards or downwards, Evidently different monitoring strategies will be required

for (a) the river segments which are never in violation of standards, (b) the segments that are almost always in violation, and (c) segments which violate the standards part of the time,

Of particular concern within the present national strategy of setting

effluent limitations is the determination and continual re-examination of

assimilative capacities of streams, either through simple correlations between

waste loads and water quality or through the use of mass-energy balance models,

Unfortunately assimilative capacities are not fixed quantities that remain

unchanged over time even under similar external loading and environmental

conditions. Internal accumulations of materials, transformations of biotic communities, and other factors may cause these capacities to change over time;

continual reassessments of these capacities are necessary to evaluate the ade-.

quacy of existing effluent controls and to estimate unused capacities available for growth,

1,3,2 General Water Resource Planning, Considerations of both the quantity and quality of water within a river segment can be separated only in a highly artificial sense, There are very few uses for water in which the quality dimensions can be ignored. Even in those instances where the quality of water as an input can vary over a large range, its effluent quality and potential

environmental impact may be of considerable importance. Quality is most signifi- cant in relationship to public drinking waters, recreation, and maintenance of high valued sports and commercial fisheries, but even coarser uses such as for industrial processes and cooling and irrigation involve quality considerations, Water resource developments and improvements, such as multiple purpose reservoirs and wetland drainage, may bring about profound changes in water quality and

present opportunities for water quality management, Furthermore, uses of land resources that are linked to the water resource system may exert important influences on water quality, and thus watershed management becomes a technique of water pollution control, particularly with respect to non-point sources,

Despite the existence of both inherent material linkages among water and related land resources and water quality and opportunities to achieve economies through integrated management, the predominant practice is to maintain separate management agencies for water quantity, water quality, and

land, There are some valid arguments about the advisability of incorporating all of these functions in a single agency, but there appear to be no valid claims as to why they should not share common data collection activities.

1,3,3 Research and Water Quality Models, In addition to the above mission-oriented purposes there are needs for data that will contribute to a better scientific understanding of water quality systems, Although there are other water quality investigations that should be included within the scope of monitoring systems, a particularly useful set of investigations relate to mass or energy balance equations or models for water quality parameters, In their most general form these models include linkages among sources of pollutants,

their transport and transformation processes in streams, their exchange

processes with bottom deposits and the atmosphere, and ecological communities that both transform foodstuffs in the water to living organisms and are ad- versely affected by toxic materials in the water, Data are required to

elucidate the kinetics of dominant transport mechanisms and reaction processes.

Development and caltbration of these mathematical representations of the real uire measurements of sources and ambient quality with a greater temporal and spatial resolution than similar needs for planning and enforce- ment,

Mathematical models are central elements in the chain of analyses that permit prediction of the consequences of variations in storage-discharge events, alternative control measures, and hydrologic variability, Also, in those places where the predictive ability of models can be demonstrated, they provide

supplementary infomacion that may lead to reductions in the size of monitoring networks.

Intensive surveys have been conducted on several streams in North Carolina from which water quality models can be calibrated and used to estimate assimilative capacities and

to

make waste-Load allocations. Gem- erally the surveys have been made under low-flow conditions, The li~ited range of flows and temperatures present in these data sets are likely to restrict severely the range over which the assuined relationships can be extrapolated with confidence. In order to extend the useful range of models developed during intensive surveys, the effect of the variations in flow and temperature on time of travel, reaction kinetics and sedimentation rates should be determined, There is very little information available from which the

dynamics

of

the stream during and after rainstorms - when most non-point loads are transmitted and have their direct impact - can be inferred. Flows,

velocities and other stream characteristics are subject

to

large and rapid variation during these times; the effect of increased loads may, or may not, be of such a magnitude as to cause violation of water quality standards,

1,4 - ta

A useful distinction among the types of water quality data relevant to network design is given by the Office of Water Data Coordination, U s S.

Geological Survey (3). The categories defined are:

1. base level information,

2. w a t e r r e s o u r c e p l a n n i n g and development, and 3 . w a t e r r e s o u r c e management.

W i t h i n t h e l i m i t e d c o n t e x t of w a t e r q u a l i t y management t h e s e c a t e g o r i e s c a n be i n t e r p r e t e d a s f o l l o w s : ( 1 ) b a s e l i n e d a t a i s g e n e r a l d a t a f o r con- s t r u c t i n g r e s o u r c e i n v e n t o r i e s , hedging a g a i n s t u n a n t i c i p a t e d n e e d s , and p r o v i d i n g a b a s i s f o r t h e d e s i g n o f more i n t e n s i v e and s p e c i f i c n e t w o r k s ;

( 2 ) p l a n n i n g d a t a p r o v i d e s i n f o r m a t i o n f o r t h e a s s e s s m e n t of w a t e r q u a l i t y problems and f o r t h e d e s i g n of p o l l u t i o n abatement measures; and ( 3 ) o p e r a t i o n l e v e l d a t a a r e c o l l e c t e d i n s u p p o r t o f d a y - t o - d a y o p e r a t i o n s , t o m o n i t o r w a t e r q u a l i t y t r e n d s t o measure e f f e c t i v e n e s s of management p r o c e d u r e s , t o d e t e c t v i o l a t i o n s o f e f f l u e n t and w a t e r q u a l i t y s t a n d a r d s , o r t o a s s e s s e f f l u e n t changes. There a r e c l e a r l y d i f f e r e n t k i n d s of networks r e q u i r e d t o s u p p l y t h e s e d i f f e r e n t t y p e s of i n f o r m a t i o n . C a t e g o r i e s 1 and 2 c a n b e s u p p l i e d by a more c o a r s e network w i t h l o n g e r a v e r a g i n g i n t e r v a l s t h a n networks t o s u p p l y i n f o r m a t i o n on o p e r a t i n g s p e c i f i c programs i n s p e c i f i c l o c a t i o n s on a d a y - t o - day b a s i s . However i n each c a s e , i n f o r m a t i o n on b o t h s o u r c e s of p o l l u t i o n and ambient w a t e r q u a l i t y must b e r e p o r t e d .

1.4.1 I n f o r m a t i o n on S o u r c e s . The amounts and s p a t i a l and t e m p o r a l

d i s t r i b u t i o n of s u b s t a n c e s t h a t p r e s e n t l y e n t e r t h e s t r e a m s from b o t h p o i n t and non-point s o u r c e s i s needed i n o r d e r t o ( a ) judge compliance o r non-compliance w i t h e f f l u e n t l i m i t a t i o n s t a n d a r d s , ( b ) d e v i s e r e g u l a t i o n and c o n t r o l s t r a t e g y

s o t h a t t h e p r e s c r i b e d ambient w a t e r q u a l i t y s t a n d a r d s a r e met, ( c ) d e s i g n sampling and a n a l y s i s programs, ( d ) p r o v i d e i n p u t d a t a f o r a p p r o p r i a t e mathe- m a t i c a l models t o p r e d i c t r e s p o n s e s o f s t r e a m s , ( d ) p r o v i d e i n f c r m a t i o n on p o s s i b l e d i s c h a r g e of t o x i c m a t e r i a l s , and ( e ) o p e r a t e a p o s s i b l e system of c o n t r o l s employing t h e t e c h n i q u e of e f f l u e n t c h a r g e s . The g e n e r a l t y p e s of s o u r c e s i n c l u d e ( a ) p o i n t - s o u r c e d i s c h a r g e s of r e s i d e n t i a l and i n d u s t r i a l w a s t e s , (b) u r b a n s t o r m r u n o f f from r e s i d e n t i a l , commercial and i n d u s t r i a l

l a n d s , and ( c ) o v e r l a n d flow from f o r e s t e d and a g r i c u l t u r a l l a n d s .

O p e r a t i o n s and enforcement c a n be e f f e c t i v e o n l y i f s o u r c e m o n i t o r i n g i s u t i l i z e d , a p r a c t i c e t h a t h a s been w r i t t e n i n t o t h e 1972 Amendments. A l l

s i g n i f i c a n t p o i n t s o u r c e s , m u n i c i p a l and i n d u s t r i a l , a r e now r e q u i r e d t o s e l f - m o n i t o r t h e i r w a s t e s . The S t a t e h a s i s s u e d g u i d e l i n e s f o r sampling and a n a l y s i s . The Environmental P r o t e c t i o n Agency h a s i s s u e d e f f l u e n t

l i m i t a t i o n s e a n d a r d s f o r s e v e r a l t y p e s o f s o u r c e s . The e f f l u e n t l i m i t a t i o n s r e q u i r e t h a t a l l d i s c h a r g e s be g i v e n a s p e c i f i e d l e v e l of t r e a t m e n t r e g a r d l e s s

o f t h e q u a l i t y o f r e c e i v i n g w a t e r s and r e g a r d l e s s of t h e q u a l i t y s t a n d a r d o f t h e r e c e i v i n g s t r e a m segment. The m o n i t o r i n g r e s p o n s i b i l i t y of t h e S t a t e w i t h r e s p e c t t o t h e s i g n i f i c a n t p o i n t s o u r c e s w i l l be minimal because s e l f - m o n i t o r i n g i s r e q u i r e d b o t h a t t h e p o i n t of d i s c h a r g e and a t s p e c i f i e d l o c a t i o n s

i n t h e r e c e i v i n g s t r e a m , The major r e s p o n s i b i l i t y of t h e S t a t e w i l l be i n c h e c k i n g t h e a c c u r a c y o f r e p o r t e d d a t a and t o e x e r c i s e s t r i c t c o n t r o l on t h e q u a l i t y of d a t a r e p o r t e d . T h i s m o n i t o r i n g e f f o r t on t h e p a r t o f m u n i c i p a l i t i e s and i n d u s t r i e s should be c o o r d i n a t e d w i t h t h e o v e r a l l m o n i t o r i n g s t r a t e g y of t h e S t a t e .

S t u d i e s on s o u r c e s s h a l l i n c l u d e :

( 1 ) i d e n t i f i c a t i o n of u n l i s t e d p o i n t s o u r c e s ;

( 2 ) e s t i m a t i o n of l o a d s from s i g n i f i c a n t p o i n t s o u r c e s a c c o r d i n g t o t y p e and d a i l y , weekly and s e a s o n a l c y c l e s of w a s t e d i s c h a r g e ;

(3) i d e n t i f i c a t i o n of raw m a t e r i a l s , s o l v e n t s and m a n u f a c t u r i n g p r o c e s s e s u s e d ; and

(4) s p e c i f i c a t i o n o f e x a c t l o c a t i o n , p l a n t s i z e and o p e r a t i n g s c h e d u l e ,

The e s t i m a t i o n of non-point s o u r c e s w i l l l a r g e l y be a S t a t e o b l i g a t i o n i n c o o p e r a t i o n w i t h a r e a w i d e p l a n n i n g a g e n c i e s , Improved n o n - p o i n t s o u r c e l o a d s should be p r e p a r e d from l a n d u s e , r u n o f f c o e f f i c i e n t s and ambient w a t e r q u a l i t y measuremen.ts. Primary f i e l d e s t i m a t e s s h o u l d be o b t a i n e d from s e l e c t e d , r e p r e -

s e n t a t i v e u r b a n and r u r a l w a t e r s h e d s ,

1.4.2 I n s t r e a m Water Q u a l i t y . A knowledge of ambient w a t e r q u a l i t y i n a s t r e a m i s r e q u i r e d t o ( a ) a s c e r t a i n r e l i a b l e and a c c u r a t e i n f o r m a t i o n on t h e

" c u r r e n t s t a t u s s ' of w a t e r q u a l i t y r e q u i r e d f o r t o t a l p l a n n i n g of w a t e r

r e s o u r c e s , ( b ) d e t e r m i n e t h e e x t e n t of compliance and non-compliance w i t h t h e w a t e r q u a l i t y s t a n d a r d s , ( c ) p r o v i d e r e l i a b l e d a t a which w i l l make i t p o s s i b l e t o a s s e s s l o n g - t e r m t r e n d s and o v e r a l l changes i n w a t e r q u a l i t y , ( d ) d e t e r m i n e t h e d e g r e e t o which w a t e r q u a l i t y i s improved a s a r e s u l t o f p o l l u t i o n a b a t e - ment measures and due t o e f f l u e n t l i m i t a t i o n s , a n d ( e ) i n d i c a t e problem a r e a s r e q u i r i n g c o r r e c t i v e a c t i o n s b e f o r e a c r i s i s s i t u a t i o n i s developed.

The g o a l of e n v i r o n m e n t a l p o l i c y i s , above a l l , t o a c h i e v e a d e s i r a b l e l e v e l of s t r e a m w a t e r q u a l i t y , The number of t r e a t m e n t f a c i l i t i e s c o n s t r u c t e d and t h e compliance w i t h e f f l u e n t l i m i t a t i o n s imposed i n t h e m s e l v e s c a n n o t e n s u r e improvement of w a t e r q u a l i t y , C o n t r o l l i n g p o i n t s o u r c e s of i n p u t does n o t a u t o m a t i c a l l y c o n t r o l t h e s t a t e o f t h e w a t e r q u a l i t y system,

Except in isolated areas where one source of waste is clearly dominant over all other sources, one-to-one correspondence cannot be established between waste inputs and ambient water quality, The water quality data obtained from a given location at a given point in time result from many-to-one transfor- mations of waste flows, environmental factors and antecedent stream conditions,

These transformations do not just involve mapping of one or more sources and other factors over a short period of time; they involve time sequences of these variables over considerable periods of time up to several months, The loading patterns, transport phenomena, and stream responses may be drastically altered under rapidly-varying conditions such as those prevailing in storm runoff,

Some effort must be undertaken to link sources and ambient water quality if the effectiveness of the control measures is to be judged, A logical technique for predicting ambient quality levels from alternative loading patterns and determining loading allocations that will satisfy water quality standards is the mass-energy balance model discussed earlier, However, this requires detailed data on flows, background levels, and reliable, sophisti- cated models for the behavior of various pollutants, With the present state of knowledge of water quality systems, there is no substitute for instream water quality monitoring, A shift in policy from the regulation of

instream water quality to effluent controls requires substantial changes in themethods and content of data collection programs, in the general .

characteristics of the monitoring system and in the criteria of its perfor-

mance.

1,5 Specifying a Monitoring Network

The design of a water quality monitoring network requires the specification of:

1, type of monitoring network: fixed or mobile, continuous or periodic,

2,

selection of an averaging period,

3 ,

determination of the design period,

4 ,

~arameters to be measured,

5, number and location of sampling sites, 6, sampling frequencies,

7,

methods of collecting samples,

8, instruments and methods of analysis, and 9, data transmission and ha.ndling techniques.

This study is confined only to the first six items,

12

1.5.1 Type of Network. As we are not generally interested in instantaneous values, continuous monitoring for short periods may be involved only for temperature and dissolved oxygen in the development of adequate mathematical models for

organic and thermal pollution. The vast majority of observations will be

periodic, The actual experience suggests that continuous monitoring techniques and instruments for water quality surveillance have a history of questionable performance,

Continuous monitoring is competitive or superior to periodic sampling only in the case of detecting violation of stream standards arising from accidental or intentional spills (2). To meet requirements of spills will make the monitor- ing methods unnecessarily complex and costly. It is recommended that the detection of spills not be made an objective of a general monitoring network and should not influence its design. This is a function which properly belongs to policing.

The monitoring network will consist predominantly of fixed sites. However, monitoring of sto-m-water quality is a situation in which mobile and continuous

sampling offer some advantages.

1.5.2 Averaging Period. The appropriate length of the averaging interval is determined by the type of parameter. For some parameters daily averages are essential for a realistic representation, For others, monthly or even annual averages may suffice, The Fntended use of data also influences the choice of a suitable averaging interval. To detect the presence of Long term trends, longer averaging periods will be adequate. For the characterization of storm- water quality, rapidly fluctuating levels of water-quality parameters will have to be monitored, In the same monitoring system, the averaging times of interest may vary widely, It should be noted that it is always possible to compute

averages over a longer period from the data sampled at smaller intervals, but the converse is not always true, The averaging periods are specified for some of the constituents

i n

water quality standards, Daily averages are stipulated for dissolved oxygen in North Carolina while for total coliforms monthly averages are prescribed.

Averaging time is one of

t h e

most significant factors that control the density sf a monitoring network both in space and time. Shorter averaging periods require a more intensive network. The spatial resolution is related to temporal resolution. The longer the desired averaging interval, the

fewer the number of stations required to depict the behavior of a constituent,

i . e . , the

shorter wavelength feacures are less important as the time period

increases. Relatively fewer sites are needed to estimate accurately the seasonal or annual concentration levels of a constituent over a given area.

At a specific location, the variance of a quality parameter decreases as

the averaging interval increases. A very small number of samples can approxi- mate the distribution of an annual average very closely.

1,5.3 Sampling Design Period. The time of the year which should be used as the baseline period to arrive at the specification of a network depends on

the temporal distribution of a parameter. The distribution of both the mean and the standard deviation have to be considered. All the parameters do not assume their maximum or minimum values simultaneously. Even for the same parameter, the mean and standard deviation may vary significantly with the time of the year. The year should be divided into discrete periods of time stationarity over which the mean and standard deviation can be assumed to be reasanably constant. The selection of the baseline period would then depend on the objective of monitoring, The values used in the design will be the averages over the baseline period. The baseline period will vary significantly with different paramef ers.

1.5.4 Parameters Sampled. Each parameter to be sampled has a preferred network design associated with it which may not coincide with the optimal requirements of any other parameter. In a multi-parameter network one is interested in the performance of several parameters simultaneously. With the limitation of resources available for monitoring, either the priorities shall have to be assigned to the parameters, or the compromises shall have to

be

made which will result in sampling some

of

the parameters at locations and frequencies other than these preferred. The latter course is usually possible because considerable flexibility in location and frequency can be achieved with a small sacrifice in effectiveness. The most stringent requirements are imposed by those parameters that are the most short-lived.

1,5.5 Spatial Density. The number and location of sampling stations is governed by the objective of monitoring and spatial distribution of a parameter.

The spatial distribution differs from pollutant to pollutant due to the differ- ences in the location of their sources and the differing transformations they undergo in the stream environment. The inter-station correlation of a parameter

gives a measure of variability of concentrations over the length sf a stream.

In a multiple-objective and multi-parameter network several compromises shall

have to be made to arrive at a final configuration. With the limited resources

available for monitoring, sampling stations cannot be established at all