G ra b S a m p le

G ra b S a m p le

M aterials that cause turbidity tend to be evenly

E q uip m ent

distributed in the w ater colum n and across the T he follow ing equipm ent w ill be needed to sam ple

stream cross-section. T herefore a “ grab sam ple” turbidity:

sufficiently represents the sam ple location. T he • sam ple can be collected at any point in the stream

A portable turbidimeter (available from D E Q ’s (either near the bank or the deepest part of the

V olunteer M onitoring Program or scientific channel) by low ering the lip of the sam ple bottle

supply houses). T hese instrum ents are below the surface of the w ater. calibrated on the nephlom etric turbidity m ethod

(see above) and m eets the criteria established

S a m p le T im ing

by E PA . T he H A C H 2100P (portable) T urbidim eter is available to local w atershed

T im ing of the grab sam ple is just as critical as site groups through D E Q ’s V olunteer M onitoring

selection. Stream flow greatly influences turbidity. Program and is referenced in this protocol. T he

T herefore, it is im portant to sam ple for turbidity

H A C H T urbidim eter kit includes the G elex during sim ilar flow conditions unless the objective Secondary Standards (for checking the

is to m onitor the differences betw een low flow and accuracy of the turbidim eter in the field), and

peak flow turbidity. For exam ple, it w ould be sm all sam ple bottles for testing turbidity w ith

inappropriate to com pare a pre-project sam ple the turbidim eter.

collected during a storm event w ith a post-project sam ple that w as collected during low er flow

• Stabilized Formazin Primary Standard K it conditions. G iven the above discussion regarding

(available from the D E Q V olunteer M onitoring site selection and sam ple tim ing, consider the Program ) for a m ore thorough, periodic,

follow ing guidelines w hen designing a sam ple: turbidim eter calibration. (see the “ C alibration”

C learly define the project objectives and •

section below )

A ny clean container for taking grab samples. m onitoring questions. T his w ill help identify sam pling location and tim ing.

C learly identify the source, project, or activity being m onitored and locate sam ple points to the Site selection procedures described in C hapter 3

S ite S electio n

closest proxim ity of these activities. (Selecting Sites) apply to turbidity m onitoring. A ll w ater quality sam ples collected to m easure

D escription of sampling point conditions of concern and consistently m onitor during those tim es and conditions.

C learly identify the time period or flow

• Identification (or L at/L ong.) of sampling site •

• D ate and time of collection If the objective is to monitor a specific activity,

then obtain turbidity sam ples upstream of the

• N ame of collector

project site during the activity as a control to m onitor background turbidity conditions.

C alibration

T hese sam ples should be collected in addition T he M odel 2100P T urbidim eter is calibrated w ith to the sam ples obtained im m ediately Form azin Prim ary Standard at the factory and does dow nstream of the project site. n o t req u ire re c a lib ra tio n b e fo re u se . W ith steady

• If the objective is to collect baseline data on field use, how ever, the H A C H C om pany turbidity, the sam ple frequency and num ber of

recom m ends recalibration every three m onths, or as locations m ust be large enough to capture the

often as experience dictates. R efer to the range of flow conditions and turbidity-

Instrum ent M anual for com plete instructions. generating activities that are occurring in the reach or basin.

F ield T urb id ity M ea surem ent P ro ced ure.

A ccuracy C heck Field check the turbidim eter against the G elex

D ata collection can begin after follow ing the Secondary Standards at the start of each set of

procedures described above for instrum ent m easurem ents. If num erous sam ples are to be

preparation and site selection. processed, periodically check the instrum ent against

the calibration standards and adjust accordingly.

1. C ollect a representative sam ple in a clean container. Fill one of the sam ple bottles

• Place the first G elex Standard (0 to 10 (included w ith the turbidim eter kit) to the line

range) in the cell com partm ent of the m eter (approx. 15-m l), taking care to handle the w ith the w hite diam ond on the vial

sam ple bottle by the top to avoid fingerprints aligning w ith the orientation m ark on the

and dirt on the bottle. C ap the bottle. m eter. C lose the lid.

• 2. W ipe the bottle w ith a soft, lint-free cloth to Press “ P O W E R ” , and w hen 0.00 show s

rem ove w ater spots and fingerprints. in the display w indow , press “ R E A D .” If

the reading is not w ithin 5% of the

3. Press the “ I/O ” button to turn the instrum ent Standard, recalibrate the instrum ent w ith

on. Place the instrum ent on a flat, steady the prim ary Form azin Standard (see

surface.

4. Put the sam ple bottle in the instrum ent cell • com partm ent so the diam ond m ark on the bottle R epeat this procedure w ith the remaining

below ).

tw o G elex Standards (0 to 100 and 01 to aligns w ith the orientation m ark on the 1000 ranges).

instrum ent.

5. Select the m anual or autom atic range by pressing the “ R A N G E ” key. “ A U T O R N G ”

D uplicate Sam ples is recom m ended and w ill be displayed. Press O btaining duplicate sam ples is im portant for

“ R E A D .” T he display w ill show “ -------

docum enting the variability from sam ple to sam ple. N T U ” then the turbidity reading in N T U .

D uplicate sam ples should be collected at a rate of R ecord the turbidity after the lam p sym bol one duplicate sam ple for every ten regular sam ples

turns off.

collected. A ll sam ples m ust be identified on a field N otes: on taking M easurem ents data sheet by:

• the G overnor’s W atershed E nhancem ent B oard A lw ays cap the sample bottle to prevent

spillage of sam ple w ater into the instrum ent. •

A lw ays place the instrument on a level,

T urb id ity D a ta A na ly sis

stationary surface. O nce the data has been stored on a com puter and on

A lw ays close the cell compartment lid during backup disks, data analyses can begin. A nalysis of m easurem ent and storage.

turbidity data depends on the specific objectives. •

D o not leave the sample bottle in the cell com partm ent for long periods of tim e.

Project M onitoring If the collected data w ill be used to determ ine

A lw ays use clean sample bottles. w hether m anagem ent activities are increasing •

A void operating instrument in direct sunlight. turbidities above a given level, then the follow ing • inform ation should be included:

M ake sure that a cold w ater sample does not fog the sam ple bottle.

• Information on the activity or project. •

A void allow ing the w ater sample’s contents to • T urbidity data upstream and dow nstream of the settle prior to taking a turbidity m easurem ent.

activity, and, depending on the objectives, •

A lw ays take turbidity measurements w ithin possibly w ithin the reach affected by the

24 hours of collecting the sam ples.

activity.

C ollecting data at these same locations before

A perm anent record of each sam pling event should the activity starts is also advisable.

be m aintained and should include: • Significant observations related to the sample

W ith this inform ation, an investigation of trends • betw een turbidity and the m anagem ent activity can

O ther ancillary environmental measurements

begin.

(see below ) • W eather and other physical conditions

R ela tio nship s b etw een turb id ity a nd o ther

• strea m cha ra cteristics. Sample date

• Sample ID

Suspended Sedim ent

A ncilla ry D a ta

If the turbidity data w ill be used to determ ine suspended sedim ent characteristics, the relationship

O nce a site is selected, other im portant descriptive betw een suspended sedim ent and turbidity for the inform ation should be recorded such as general

particular sites m ust be established. C ontact the flow conditions and depths, and references to

m entor for specific sam pling procedures that m ust landm arks such as tributary nam es, river m ile,

be follow ed for suspended sedim ent. roads, and bridges. T he latitude and longitude of

the site is an im portant piece of inform ation that can

be obtained from a topographic m ap or from a

Stream flow Stream flow inform ation can be collected at the

global position device (G PS). sam e sites as the turbidity data. M onitors should

investigate the relationships betw een increases and Inform ation about the landow ner and contacts decreases in stream flow and turbidity. T he O regon (telephone, address, E -m ail) should be recorded.

W ater R esources D epartm ent is developing a

D o c u m en t a la n d o w n e r’ s g ra n te d p e rm issio n fo r protocol for m easuring stream flow . C ontact a

a c c e ss to p riva te la n d s.

A photograph of the m onitoring site can be useful turbidity m entor for m ore inform ation on this. for locating equipm ent. G uidance for photo

docum entation of m onitoring sites is provided by

N o rth w e st a n d A la sk a . E PA region 10, 910/9-91-

R eferences

001. 166 pp. Stednick, J.D . 1991. W ildland water quality

B eschta, R .L ., Jackson, W .L . 1980. T urbidity and

A cadem ic Press, Inc., San suspended sedim ent relationship. P 271-282 in

sa m p lin g a n d a n a ly sis.

D iego, C A .

P ro c e e d in g s, sym p o siu m o n W a tersh e d T he project coordinator is directed also to the E PA m a n a g e m en t . A m er. Soc. O f C iv. E ngineers.

V olunteer M onitor’s G uide to Q uality A ssurance

B row n, G . 1983. Forestry and water quality.

Project Plans (E PA 1996).

O SU B ookstores Inc., C orvallis, O R . 142 pp. M acdonald, L H ., Sm art, A .W ., and W issm ar, R .C .

1991. M onitoring guidelines to evaluate effects of fo restry a ctivities o n strea m s in th e P a cific