Section 319
NONPOINT SOORGE PROGRAM SOGGESS STORY
Community-Based Efforts Decrease Algae Toxins in Carter Lake
\A/ t h H I H Runoff and lakebed sediment resuspension led to elevated nutri-
vva jy i nprovea ent and turbidity |eve|S in Carter Lake (wnicn Nes in both |0wa and
Nebraska). As a result, Iowa placed Carter Lake on its Clean Water Act (CWA) section 303(d) list
because of excess algae and turbidity (in 2004) and low dissolved oxygen (in 2008). The Nebraska
Department of Environmental Quality (NDEQ) added Carter Lake to the state's 2006 CWA section
303(d) list because of phosphorus, nitrogen, chlorophyll a, algal toxins and pH impairments. A commu-
nity-based implementation effort to restore the lake has successfully reduced nutrient concentrations
and blue-green algae (and their microcystin toxins). As a result, NDEQ will propose to remove Carter
Lake's algae toxin impairment from the state's 2012 CWA section 303(d) list.
Problem
Carter Lake (Figure 1) is a 315-acre oxbow lake
along the Missouri River. The lake, which is in both
Nebraska and Iowa, drains approximately 2,722 acres
of primarily urban-residential and commercial land.
Elevated nutrients in the lake have caused a
number of water quality problems. Total phospho-
rus levels in the lake have exceeded 300 parts per
billion (ppb) while nitrogen levels were as high as
5,100 ppb. The occurrence of blue-green algae
blooms (associated with high nutrient levels) led
officials to begin monitoring for microcystin toxin
in 2004. The first samples collected from the lake
exceeded the beach posting criterion of 15 ppb. In
2005 the beach posting criterion was changed to
20 ppb. From 2005 through 2008, 10 of the 83 toxin
samples collected exceeded 20 ppb, causing offi-
cials to post warnings at the beach for 21 weeks.
As a result of the water quality problems, Iowa
placed Carter Lake on its 2004 CWA section 303(d)
list because of excess algae and turbidity. NDEQ
added Carter Lake to the Nebraska's 2006 CWA
section 303(d) list because of phosphorus, nitro-
gen, chlorophyll a, pH and algal toxin impairments.
NDEQ also added PCBs (in fish tissue) to the list of
Carter Lake impairments in 2004.
Iowa Department of Natural Resources (IDNR)
and NDEQ prepared a total maximum daily load
for algae/algal toxins, chlorophyll a, total phospho-
rus, total nitrogen and pH at Carter Lake in 2007.
Nutrient sources were linked to nonpoint source
runoff from the watershed and from the organic-
rich sediment in the bottom of the lake. Lakebed
sediments were frequently resuspended by boat
wakes and the bottom-feeding activity of rough fish
(such as carp, quillback and bullheads).
Figure 1. Officials apply alum and sodium aluminate
to Carter Lake.
Project Highlights
In 2006 the cities of Carter Lake (Iowa) and Omaha
(Nebraska) joined forces with local and state agen-
cies to begin a Community-Based Planning Process.
As part of the planning process, a group of interest-
ed citizens formed the Carter Lake Environmental
Assessment and Rehabilitation (CLEAR) Council.
In 2008 the CLEAR Council, with assistance from
its local and state agency partners, completed the
Carter Lake Water Quality Management Plan. The
plan outlines more than $6 million worth of possible
restoration work. With a plan in place, partners initi-
ated the Carter Lake Water Quality Project in 2008.
First, the partners hired a project coordinator using
CWA section 319 funds from Nebraska (years 1-2)
and Iowa (years 3-4).
Partners have completed many watershed treat-
ments, including installing grass swales and rain
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gardens. The city of Carter Lake installed five rain
gardens with a combined total area of 17,503 square
feet (Figure 2). Partners are conducting an extensive
nutrient educational effort targeted at fertilizer use
and pet waste management; they recently expanded
the education effort to include aquatic vegeta-
tion management. In-lake treatments consisted of
applying algaecide, alum and sodium aluminate (see
Figure 1), establishing a 100-acre no-wake zone with
a 5-mile-per-hour watercraft speed limit to minimize
displacement of sediments, and renovating the fish-
ery (replacing rough fish with largemouth bass, blue-
gill and channel catfish).
Other work that will be
implemented includes
adding stormwater
detention cells, installing
grass swales, creating
wetlands, stabilizing the
shoreline, performing
targeted lake dredg-
ing and conducting a
second alum treatment.
Partners expect to
completely implement
the restoration efforts
described by the plan
in 2013.
Figure 2. The city of Carter Lake
installed five rain gardens to treat
stormwater runoff.
Results
Monitoring conducted since 1990 shows that the
restoration efforts have made a difference. Nutrient
levels have dropped, resulting in lower algal densi-
ties and decreased levels of the microcystin toxin
(Table 1). The beach has not been closed by high
microcystin levels since before the in-lake alum and
algaecide treatment in 2010 (Figure 3). On the basis
of those data, NDEQ will propose to remove Carter
Lake's algal toxin impairment from Nebraska's 2012
CWA section 303(d) list. The lake will remain on
Nebraska's impaired waters list for phosphorus,
nitrogen, chlorophyll a, pH and PCBs (in fish tissue).
Table 1. Carter Lake nutrients and microcystin
data (1990-2011)
Total nitrogen
Total phosphorus
Algae microcystin toxin
1990-2009
Average levels (ppb)
2,782
185
8.63a
2010-2011
Average levels (ppb)
1,340
70
0.31
I
S 30
P-
^a.
rj
e
•K 20- -
&
-^ 11- T-
s 15
Q
Carter Lake-Mkrocystin Toxin Concentrations
I
1 1
ill
r-i r-i r-i
Pre-Lake Treatment
Beach Posting
Criterion (20ppb)
/
1 ||| |||
PM PM
Post-Lake Treatment
...,l,i, , ,
® T—
O o
PM S
Figure 3. Implementing in-lake treatment and watershed
restoration practices helped to eliminate beach closings.
Carter Lake's water clarity has improved, creating
a secondary problem of aquatic vegetation over-
growth. Although the vegetation hampers water-
based recreation, it has helped the newly stocked
game fish flourish. In July 2011 the project team
initiated vegetation harvesting in critical areas of the
lake. A vegetation management plan will be devel-
oped and implemented to address future concerns.
Partners and Funding
' Microcystin data includes the average for 2004-2009 only.
Numerous agencies and stakeholders are
involved in planning, implementing and monitor-
ing this approximately $4.7-million water quality/
lake restoration project. Partners include IDNR,
Nebraska Game and Parks Commission, Omaha,
Papio-Missouri River Natural Resources District,
city of Carter Lake, University of Nebraska-Lincoln,
Iowa State University, Metropolitan Area Planning
Agency, Iowa Division of Soil Conservation, NDEQ,
West Pottawattamie County Soil and Conservation
Service District, and Carter Lake Preservation
Society. Eight different funding sources are sup-
porting water quality management plan imple-
mentation. To date, $2,357,198 has been provided
through Nebraska Game and Parks Commission
Aquatic Habitat Program, NDEQ CWA section
319 funds, IDNR Special Appropriations, Omaha
and the city of Carter Lake. In addition to those,
future funding will be supplied through IDNR CWA
section 319, Nebraska Environmental Trust and
Papio-Missouri River Natural Resources District.
Ill
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-11-001KK
September 2011
For additional information contact:
Mary Schroer
Nebraska Department of Environmental Quality
402-471-6988 • mary.schroer@nebraska.gov
Rachel Glaza
Iowa Department of Natural Resources
515-281-8158 • Rachel.Glaza@dnr.iowa.gov
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