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Water: Total Maximum Daily Loads (303d)

Total Maximum Daily Loads (TMDLs) at Work: Nebraska

TMDLs at Work

Keeping Fremont Lake #20 beaches open and toxin-free: Phosphorus TMDL implementation prevents toxic algae blooms and restores recreational uses.

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 Impaired Waters and Total Maximum Daily Loads Web site.

            
TMDL at a Glance:
Factors causing impairmentPrimary recreation designated use was impaired from toxic algal blooms caused by excessive phosphorus loading; a TMDL was developed for phosphorus
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
Approved TMDL document Fremont Lake #20 Phosphorus TMDL (approved September 2007) (PDF) (14pp, 826K, about PDF)

 
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Figure 1. Beach closing sign used at Fremont Lake #20.

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 public to exercise caution when boating or potentially coming into contact with the water. Figure 1 shows the signs used to notify the public of closed beaches at Fremont Lake #20.

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.

 

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 (2007 Toxic Blue-green Algae and Bacteria Sampling Results Exit EPA Disclaimer ).

 

What is the current status of Fremont Lake #20 as a result of the TMDL process?

Nebraska Chart
Figure 2. Changes in phosphorus and microcystin concentrations in Fremont Lake #20 after alum treatment

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 present. Figure 2 shows the improvements in phosphorus and microcystin concentrations after alum treatment in 2007. Average summer phosphorus concentrations decreased from 110 micrograms per liter (μg/L) to 21 μg/L, chlorophyll decreased from 82 μg/L to 8 μg/L, and microcystin concentrations decreased from an average of 21 μg/L to concentrations below the reporting limit of 0.15 μg/L. There were no beach postings in 2008 as the maximum microcystin concentration reported that year was 0.23 μg/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 Category 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:

  • 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.
  • 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 boating, 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.
  • 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 established strong partnerships necessary to address other water quality problems in the Fremont Lake watershed.

For more information on the Fremont Lake #20 phosphorus TMDL, contact Paul Brakhage (paul.brakhage@nebraska.gov), Water Quality Assessment Section, NDEQ, (402) 471-4224.

For more information on the Nebraska TMDL Program, visit Impaired Waters and Total Maximum Daily Loads (TMDLs) Exit EPA Disclaimer


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