What Is a Secchi Disk?
Father Pietro Angelo Secchi, scientific
advisor to the Pope, was asked by
Commander Cialdi, head of the
Papal Navy, to develop and test a
new water transparency instrument
in the Mediterranean Sea. This
instrument, now named the "Secchi"
disk, was first lowered from the papal
steam yacht I'Immacolata Concezione
(The Immaculate Conception) in the
Mediterranean Sea on April 20, 1865.
The typical Secchi disk used in lakes
is an 8-inch disk with alternating
black and white quadrants (like a
checkerboard). It's lowered into the
water until  the observer can no longer
see it. The depth of disappearance,
called the Secchi depth, is a measure
of the transparency of the water.
Transparency decreases as the amount of
particulate materials—such as algae and
suspended sediment—increases. The
amount of algae  that grows is affected
by the amount of nutrients coming from
sewage treatment plants, septic tanks,
and lawn and agricultural fertilizer, as
well as suspended sediments washed
from construction sites, agricultural
fields, urban storm  runoff, or churned
upward from bottom deposits.
                                                            INTO
                                               with the Great North American Secchi Dip-In
       he Great North American Secchi Dip-In is celebrated each
     I year in the first 2 weeks of July. Volunteer monitors across
  v—'  North America take to their local lakes and reservoirs (and also
estuaries, rivers, and streams) to measure water transparency. Sponsored
by the North American Lake Management Society (NALMS) and the
U.S. Environmental Protection Agency (EPA) and directed by Kent
State University, the Dip-In accepts data from Secchi disks and other
instruments, as well as temperature and pH data. The data collected are
used to assess the transparency of volunteer-monitored waterbodies in the
United States and Canada. The Dip-In collects valuable data on lake usage
and user perceptions of water quality.
One of the goals of the Dip-In is to increase the number of volunteer
monitors and to spark public interest in environmental monitoring. The
volunteer monitoring programs' efforts are a much appreciated and highly
valuable part of many states' monitoring efforts. Quality assurance is
enhanced  if the volunteer participates in both the national effort and local
activities.
The Dip-In also provides a national perspective on water quality. Since
1994, more than 6,000 trained volunteers have generated 27,000 data
entries. The data give a comprehensive glimpse of lake water transparency
at volunteer-monitored sites across North America and the rest of the
world. Scientists and volunteers observe how transparency varies according
to water type, regional geology, and land use.
Kent State University provides public access to the Dip-In monitoring data
through a  Web site. The site also includes information on a number of
common monitoring variables.

   Transparency is a good indicator of the impacts from human
   activity on the land surrounding the water body. If transparency
         is measured through the  season and from year to year,
                 trends in transparency can be observed.
                       Transparency can serve as an early
                          warning that activities on the land
                           are affecting water quality.
                                Dip-In Web site
                             http://dipin.kent.edu
                                                                                        S-EPA
                                                United States
                                                Environmental Protection
                                                Agency

                                                EPA 841-F-03-008

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The History of the Dip-In
The first Great American Dip-In in 1994 drew an impressive 40 percent
response rate from those contacted. Dip-In '94 involved more than 800
volunteers from six Midwest states— Indiana, Illinois, Michigan, Minnesota,
Ohio, and Wisconsin. In 1995 the Dip-In was expanded to include volunteers
from across the United States. Some 2,000 volunteers from 37 states and
2 provinces of Canada signed up, and organizers added estuary and river
programs to the sites sampled. By 1998 the Dip-In had spread even further, as
Canada became an official Dip-In member.

Get Involved!
If you or your volunteer monitoring group has not yet joined in the fun, here
are some reasons to Dip-In this summer:
1. Educate the public about water quality issues by alerting the media to your
   Dip-In activities.
2. Local Dip-In activities can boost your membership.
3. Get a sense of involvement in an international monitoring effort.
4. Provide a sense of accomplishment by distributing Dip-In results to your
   participants.
To enroll, visit http://dipin.kent.edu.
Each year, along with the Dip-In, EPA and
NALMS (www.nalms.org) celebrate the
entire month of July as "Lakes Awareness
Month." The surface area and number
of lakes in North America far exceed
those of any other continent, yet lakes
are our most underappreciated natural
resource. We use lakes for many purposes
such as water supply for municipal,
industrial, and agricultural use; recreation,
including boating, swimming, and fishing;
flood control; and aesthetic enjoyment.
Celebrate your lake and get involved with
local efforts to keep it clean!
Here are five things you can do to protect your lake's water quality:
• Organize a lakeshore dean up to collect trash and litter washed up on
  shore.
• Recycle used motor oil.
• Clean off recreational equipment after use to stop aquatic hitchhikers.
• Use pump-out stations for boat waste.
• Let natural vegetation grow by the lake—mow and fertilize less!

For more information, visit www.epa.gov/owow/lakes,
www.epa.gov/owow/monitoring/volunteer or www.nalms.org.
RESOURCES
Volunteer Monitor
www.epa.gov/owow/monitoring/
volunteer/vm_index.html
The Volunteer Monitor newsletter
facilitates the exchange of ideas,
monitoring methods, and practical
advice among volunteer environmental
monitoring groups across the nation.

National Directory of Volunteer
Monitoring Programs
http://yosemite.epa.gov/water/volmon.nsf
This directory lists volunteer
organizations around the country
engaged in monitoring rivers, lakes,
estuaries, beaches, wetlands, and ground
water, as well as surrounding lands. It's
intended to serve as a living document
that will grow and change with the
continued flourishing of the volunteer
monitoring movement nationwide.

Managing Lakes and Reservoirs
www.nalms.org/bkstore
This manual, published by NALMS
and the  Terrene Institute in 2001, deals
with the very broad subject  of protecting
and managing lakes and reservoirs.
It's written not only for scientists and
engineers but also for informed citizens
who are interested in protecting and
managing lakes.

Catalog of Federal Funding Sources
for Watershed Protection
www.epa.gov/watershedfunding
EPA has developed a searchable,
interactive Web site to support watershed
stakeholders' efforts to secure funding to
implement watershed protection projects
such as volunteer monitoring projects.
The Web site offers users access to a
database of approximately 100 programs
offering  financial assistance (grants,
loans, cost-sharing) specially geared
towards  watershed-related projects.

      CMore Information on Dip-In:
            Dr. Bob Carlson
      eat North American Secchi Dip-In
      department of Biological Sciences
          Kent State University
            Kent, Ohio 44242
           Phone: 330-672-3992
         E-mail: Dipln@kent.edu
               June 2003

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