POLICY--The use of Fluorescent dyes in hydrologic studies

                                                     May 16, 1966


To:       District Chiefs and Staff Officials, Water Resources Division

From:     Acting Chief Hydrologist

Subject:  POLICY--The use of Fluorescent dyes in hydrologic studies

As you know, many Federal agencies such as the Geological Survey and
the Public Health Service, as well as many state and local agencies,
universities, and private groups, have used fluorescent dyes extensively
as tracers in various surface water, ground water, and oceanographic
studies.  All of these agencies naturally have been concerned by the
possibility of harmful effects of the dyes on people or on aquatic plant
and animal life.

Although there have been a number of studies of the toxic effects of
Rhodamine B and fluorescein, past attempts on the part of WRD officials
to obtain an authoritative, definitive statement regarding the use of
the dyes for water tracing purposes have not been fruitful.  In early
1964 we did get an unofficial opinion by the U.S. Food and Drug
Administration that there was little likelihood of toxic results from
the low concentrations which we use.

Recently, however, the Federal Water Pollution Control Administration
raised the question of discontinuing the use of Rhodamine B, specifi-
cally, because of its potential as a carcinogen (cancer-producing
agent).  A re-evaluaiton of existing literature on the subject by
Public Health Service resulted in a policy statement which is attached.
We concur in the policy stated by Public Health Service and have so
indicated in the statement developed by us and attached hereto.
Existing information indicates that use of dyes at low levels of
concentration should not be harmful, thus our statement emphasizes
the importance of careful determinations of expected dye concentrations
and requires that the actual concentrations be carefully monitored and

Dyes have been used in both surface water and ground water
investigations but the principal use has been in connections with
studies of stream flow.  Policies and criteria as discussed herein
were developed specifically for surface water studies.  Any planned
use of dyes for ground-water studies should be discussed with and
approved by this office prior to the time that firm plans are
developed.  Sufficient information should be presented to permit
an evaluation of the degree of hazard involved to users of the
ground-water supplies.


Little, if any, change in current operational procedure for surface
water studies will be necessary, because current procedure conforms
with that outlined in the attached policy statement with the primary
exception of documenting the need for exercising care when computing
dosages and selecting injection sites.

For protective as well as informational purposes public relations
is an important aspect of tracer studies.  For most time-of-travel
measurements and for discharge measurements to the extent appropriate,
the following three-point procedure is recommended.

   1.  If an agency, inter-agency commission, or other group is
       responsible for activities in a given stream, obtain that
       groups' endorsement of the study well in advance.

   2.  In advance, notify other Federal, state, county, and local
       health, fish and game, pollution control, and water-supply
       agencies having jurisdiction along or immediately below the
       study reach.  Industrial water users also should be notified,
       if appropriate.

   3.  Provide news media with ample material for local release in
       advance of the study, to inform and warn the general public.

                                     E. L. Hendricks

[Contact the Branch of Operational Support, Reston, for a copy of
the attachment(s)].

WRD Distribution:  A,B,S,FO,SL

Key Words:  Dye Tracer, Time of Travel, Fluorescent Dyes