United States
Environmental Protection
Agency
Total Maximum Daily Loads
THSDLs
Phosphorus TMDL Implementation Prevents Toxic
Algae Blooms and Restores Recreational Uses
Visitors to the Fremont Lake State Recreation Area in east central Nebraska have a choice
of 20 sandpit lakes for fishing and passive recreational activities. However, only two of
the lakes provide opportunities for swimming, and one of those, Fremont Lake #20, was
not an option from June 2004 through June 2006. Known for its two swimming beaches
and boating, Fremont Lake #20 remained closed for approximately 25 weeks during this
two-year period because of toxic, blue-green algae. Microcystin, a toxin that some types
of blue-green algae create can produce rashes, lesions, and blisters on humans, pets,
and livestock. In extreme cases, microcystin can be fatal if ingested. After detecting
microcystin in Fremont Lake #20, management agencies closed the beaches and posted
information advising the
TMDL at a Glance
Fremont Lake #20
Phosphorus TMDL
(approved September 2007)
http://epa.gov/region7/water/pdf/
fremont_lake_20_tmdl_revised.pdf
Factors causing impairment
Primary recreation designated use was impaired from
toxic algal blooms caused by excessive phosphorus
loading
Sources contributing to impairment
Lake-bottom sediments rich in organic matter,
groundwater inflow, runoff from the surrounding
watershed
Restoration options
Treating the lake with aluminum sulfate
Stakeholder involvement
Nebraska Department of Environmental Quality,
Lower Platte North Natural Resource District,
Nebraska Game and Parks Commission, and the
University of Nebraska-Lincoln
Status of waterbody
Aluminum sulfate treatment occurred in October
2007; weekly monitoring at East Beach showed no
health alerts during 2008
Benefits to stakeholders
Safer recreational water quality, aesthetic
improvements
public to exercise caution when
boating or potentially coming
into contact with the water.
Figure 1 shows the signs used
to inform the public.
The Nebraska Department
of Environmental Quality
(NDEQ) included Fremont
Lake #20 on the 2006 Nebraska
Integrated Report because the
toxic algae impaired the lake's
primary contact recreation
designated use. In 2007 NDEQ
developed the Fremont Lake
phosphorus TMDL and
implemented a strategy that
included treating the lake
with aluminum sulfate (alum)
to reduce nutrient levels and
prevent excessive algal blooms.
As a result of the treatment,
the beaches of Fremont
Lake #20 remained open to
swimmers in 2008. Figure 2
shows Fremont Lake #20 after
NDEQ treated it to remove
phosphorus.
TOXIC ALGAE
WARNING
Beach Closed
Until Further Notice'
Figure 1. Beach closing sign used at Fremont Lake #20.
Figure 2. Fremont Lake #20 after alum treatment.
What is a total maximum daily load (TMDL)?
It is a study or analysis that calculates the maximum amount of a pollutant that a waterbody can receive and still meet
water quality standards. The TMDL establishes a pollutant budget and then allocates portions of the overall budget to
the pollutant's sources. For more information on TMDLs, visit EPA's website at www.epa.gov/owow/tmdl.
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How are TMDLs at work in Fremont Lake
#20?
NDEQ initiated the phosphorus TMDL for Fremont Lake
#20 because of the presence of algal toxins in the lake
and the subsequent beach closings in 2004. From June
2004 to June 2006, 28 percent of algae toxin samples
collected from Fremont Lake #20 by the Lower Platte
North Natural Resource District and NDEQ exceeded the
beach-closing criterion.
The TMDL process provided the planning framework
for identifying the problem, developing a restoration
goal, and determining the necessary level of controls
to restore the beneficial uses of Fremont Lake #20.
Implementing the TMDL began almost immediately
after the U.S. Environmental Protection Agency (EPA)
Region 7 approved it. NDEQ is partnering with the
Nebraska Game and Parks Commission and the University
of Nebraska-Lincoln to conduct weekly monitoring of the
swimming beaches. Weekly monitoring data are available
online to ensure that recreational users have access to
information on the lake's conditions (www.deq.state.ne.us/
Beaches.nsf/LakeSampling).
What is the current status of Fremont Lake
#20 as a result of the TMDL process?
Before treatment, the beaches on Fremont Lake #20 were
closed, and health alerts were issued for approximately one-
third of any summer, making it one of the most affected
lakes in the state. After the alum treatment, the lake has
experienced excellent water quality with little algae pres-
ent. Figure 3 shows the improvements in phosphorus and
microcystin concentrations after alum treatment in 2007.
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Average summer phosphorus concentrations decreased from
110 |ig/L to 21 |ig/L, chlorophyll decreased from 82 |ig/L
to 8 |ig/L, and microcystin concentrations decreased from
an average of 21 |ig/L to concentrations below the report-
ing limit of 0.15 |ig/L. There were no beach postings in 2008
as the maximum microcystin concentration reported that
year was 0.23 |ig/L. Fremont Lake #20 has remained off the
health alert list, and beaches have remained open, leading to
increased recreational opportunity. The lake appears on Cat-
egory 4A of the Nebraska 2008 303(d) list because a TMDL
has already been developed.
How did local stakeholders benefit from the
TMDL process?
Management practices applied in Fremont Lake #20 to
achieve the TMDL targets and restore the lake's beneficial
uses are expected to provide the following benefits to the
stakeholders:
O Improved recreation and aesthetics. Users of Fremont
Lake #20 have cleaner and safer water to engage in their
recreational activities such as swimming, fishing, and
boating. Posting water quality information online also
allows users to make more informed decisions as to their
recreational activities.
O Increased tourism dollars into the local economy.
As many as 800,000 people visit the Fremont Lake State
Recreation Area each year. Before treatment, Fremont
Lake #20 had the reputation of being the most affected
lake in the state for toxic algae. As a result, recreational
enthusiasts spread the word that the lake was not open
for business. As one of the popular lakes for power boat-
ing, it is possible that its closing resulted in a decline in
annual visitors. With improved water quality, the lake
will likely help to retain or increase the number of visitors
to the recreation area.
O Established effective partnerships. The treatment of
Fremont Lake #20 was made possible through funding
provided by the Nebraska Environmental Trust and the
Nebraska Game and Parks Commission. Funding for
water quality monitoring was provided by the University
of Nebraska-Lincoln and CWA sections 106 and 319 funds
administered by NDEQ and EPA. The cooperation among
NDEQ and other stakeholders in the watershed has estab-
lished strong partnerships necessary to address other
water quality problems in the Fremont Lake watershed.
Figure 3. Changes in phosphorus and microcystin concentrations in Fremont
Lake #20 after alum treatment.
For more information on the Fremont Lake #20 phosphorus TMDL, contact
Paul Brakhage, Water Quality Assessment Section, NDEQ, paul.brakhage@nebraska.gov, (402) 471-4224
For more information on the Nebraska TMDL Program, visit www.deq.state.ne.us/SurfaceW.nsf/Pages/TMDL
&ER&
December 2009
EPA841-F-09-002N
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