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EPA Region 7 TMDL Review
TMDLID: KS-KR-17-LM019001 State: KS
Document Name: MILFORD LAKE
Basin(s): KANSAS-LOWER REPUBLICAN
HUC(s): 10250017
Water body(ies): MILFORD LAKE
Tributary(ies): BUFFALO CREEK, ELM CREEK, FIVE CREEK, MULBERRY CREEK (36), PEATS
CREEK, REPUBLICAN RIVER, SALT CREEK, WOLF CREEK
Pollutant(s): EUTROPHICATION (NUTRIENTS/CHLOROPHYLL-A/TROPHIC STATE). LOW
DISSOLVED OXYGEN
Submittal Date: 1/14/2014 Approved: Yes
Submittal Letter and Total Maximum Daily Load Revisions
The state submittal letter indicates final TMDL(s) for specific pollutant(s) and water(s) were adopted by the state,
and submitted to the EPA for approval under Section 303(d) of the Clean Water Act [40 CFR § 130.7(c)(1)]
Include date submitted letter was received by the EPA, date of receipt of any revisions and the date of original
approval if submittal is a revised TMDL document.
The Kansas Department of Health and Environment officially submitted the TMDL document for Milford
Lake to the U.S. Environmental Protection Agency on January 14, 2014. Revisions were submitted by the KDHE
in an email dated April 11 and May 26,2014, in response to EPA comments dated March 26, 2014,
Water Quality Standards Attainment
The targeted pollutant is validated and identified through assessment and data. The water body's loading
capacity for the applicable pollutant is identified and the rationale for the method used to establish the cause-and-
effect relationship between the numeric target and the identified pollutant sources is described. The
TMDL(s) and associated allocations are set at levels adequate to result in attainment of applicable water quality
standards [40 CFR § 130.7(c)(1)], A statement that the WQS will be attained is made.
Milford Lake is listed in Category 5 - the Section 303(d) list - of the Surface Water Quality Integrated Report
because its designated uses are impaired by eutrophication(2004 and 2012 Integrated Reports), and low dissolved
oxygen (2002,2004,2008,2010 and 2012 Integrated Reports) based on assessment data collected from
monitoring sites within the lake by the KDHE and the United States Army Corp of Engineers. Excessive nutrient
loads are contributing to objectionable algal blooms and low dissolved oxygen, thus impairing aquatic life,
domestic water supply and primary contact recreation within Milford Lake.
Lake Monitoring Sites: The KDHE Station LM019001 in Milford Lake. Fifteen surveys conducted by the
KDHE in calendar years 1976, 1980, 1982, 1988, 1991, 1994. 1996. 1997, 1998, 2000,2003,2006, 2009 and
2012. The USACE selected in-lake monitoring sites for their sampling in years ranging from 1996-2012.
Stream Data: There are eleven KDHE stream monitoring stations within the Milford Lake watershed, of which
all but SC711 are listed as impaired on the 303(d) list for total phosphorus. Summary stream data are detailed in
Table 8 of the TMDL document.
Stream Chemistry Monitoring Sites (period of record).
Station SC231 Republican River Near Hardy, Nebraska (1990-2012)
Station SC503 Republican River near Clay Center (1990-2012)
Station SC504 Republican River near Clay Center (rotational) (1990-2012)
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Station SC509 Buffalo Creek near Concordia (1990-2012)
Station SC510 Republican River near Rice (1990-2012)
Station SC649 Peats Creek near Clifton (rotational) (1993-2011)
Station SC650 Salt Creek near Mollis (rotational) (1993-2009)
Station SC707 Wolf Creek near Concordia (rotational) (1994-2010)
Station SC709 Elm Creek near Ames (rotational) (1995-2011)
Station SC710 Mulberry Creek near Clifton (rotational) (1995-2011)
Station SC711 Five Creek near Clay Center (rotational) (1996-2012)
Flow Record:
The United States Geological Survey Gages:
Gage 06853500 Republican River near Hardy, Nebraska (1980-2012)
Gage 06858000 Republican River at Concordia, Kansas (1980-2012)
Gage 06856600 Republican River at Clay Center, Kansas (1980-2012)
Current Condition: The KDHE sampled the main basin of Milford Lake 15 times over the period of record,
with the majority of the sampling events taking place during the summer months of June and July, The
chlorophyll a concentration average over the entire period of record of the KDHE data for Milford Lake is 17.57
micrograms per liter. The more recent chlorophyll a concentration average for the KDHE samples obtained from
1996-2012 is 21.4 pg/L, and 67.9 pg/L in the 2012 survey. The USACE has sampled the main basin of Milford
Lake 22 times since 2004. The USACE collected one to six samples between April and September during the
years that they sampled the main basin. The annual average chlorophyll a concentration based on the USACE
data in Milford Lake is 16.29 ng'L. Utilizing both the KDHE and the USACE main basin data, the annual
average chlorophyll a concentration since 1996 in Milford Lake is 19,45 ng/L, The TMDL document includes
the Carlson trophic state index of 57.01 as calculated from the average chlorophyll a concentration of 21.4 jig L,
and a TS1 of 71,98 calculated from the current (2012) chlorophyll a reading of 67.9 ng/L. Based on this data and
corresponding trophic indices, Milford lake is considered fully eutrophic to hypereutrophic.
Another indication of eutrophication and algal biomass were the Seechi depth transparency readings obtained by
the KDHE in Milford Lake. Secchi depths had an annual average of 1.59 meters, with the lowest depth of 1.00 m
observed in 1996 and the greatest depth of 2.42 m observed in 2006. The Secchi depth readings obtained by the
USACE had an annual average of 1.32 m from 2005-2012. Figure 3 of the TMDL document details the annual
average Secchi depth measurements within Milford Lake. The average turbidity value obtained by the KDHE in
Milford Lake was 5.38 nephelometric turbidity units and ranged from 1.8 NTU to 10.45 NTU. The average total
suspended solids concentration in Milford Lake was 6,52 milligrams per liter for the KDHE data and 6,98 ing/L
for the USACE data over the entire period of record. The Carlson TSI value for Secchi depth of Milford Lake
consistently indicates slightly to fully eutrophic conditions.
The average total nitrogen and total phosphorus concentrations over the entire period of record are 1.17 mg/L and
0.14 mg/L respectively for the KDHE sampling data. The USACE data yielded annual averages of 1.01 mg/L of
TN and 0.20 mg/L of TP. The recent average TN and TP concentrations for the combined data sets since 1996
are 1.05 mg/L and 0.18 mg/L, respectively. The maximum TP concentration of 0.30 mg/L was observed in 1996.
Data for calculating TN is not available prior to the 1994 sampling event and a maximum TN detection of
1.60 mg/L occurred in 2011. The annual average TP and TN concentrations within Milford Lake are detailed in
Figures 4 and 5 of the TMDL document. The TSI value for total phosphorus in Milford Lake consistently
indicates very eutrophic conditions.
The average dissolved oxygen concentrations, depths and average temperature of Milford Lake sampling
sites are summarized in Table 10 of the TMDL document for the period of record. In the sampling years 1976,
1982, 1994, 1996, 1997, 1998, 2000, 2003 and 2006 Milford Lake had average dissolved oxygen excursions
lower than the 5 mg/L Kansas water quality criterion at sampling depths averaging greater than 3 meters. The
year 2000 was the only sampling year that had DO concentrations of less than 5 mg/L at the shallow, 0-3 meter
depth range.
These data on nutrient concentrations, and the trophic response and DO concentrations in Milford
Lake demonstrate that the lake is not meeting Kansas' water quality standards and criteria for nutrients and
dissolved oxygen.
The KDHE used the USACE and the KDHE data (2008 - 2012) in water quality model simulations and
assessment of eutrophication of Milford Lake. The KDHE used stream chemistry and flow data on the
Republican River (2008-2012) and FLUX to calculate nutrient concentration inputs to the BATHTUB reservoir
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model from stream inflows. The BATHTUB results for the current average lake condition and necessary TMDLs
to achieve the endpaint/goal of 10 fig/L chlorophyll a and 5 mg/L or higher DO are detailed in Table 11 of the
TMDL document.
Table 1. Milford Lake current average conditions and TMDL based on BATHTUB
Lake Inflow
Current
Average
Condition
TMDL Condition
Percent Reduction
Required
TP - Annual Load (tons year)
1,216,912
148,341
88
T i Concentration (pg L)
287
83.3
71
TN - Annual Load (tons-year)
4,875,835
674.882
86
TN - Lake Concentration (pg L)
1722
427.8
75
TMDL Calculation: The impairments caused by eutrophication and low dissolved oxygen are addressed
collectively by the development of a TMDL document that limits the TP and TN loads to Milford Lake. Based on
the relationships between eutrophication and results of BATHTUB modeling, the TP loading capacity for Milford
Lake is established at 148,341 pounds per year (772 pounds per day), and the TN loading capacity is established
at 674,882 lb yr (2866 lb/day), To meet the target loads, overall reductions of 88 percent and 86 percent of the
currently modeled TP and TN loads are required, respectively. The TP and TN loads from the watershed were
calculated using FLUX, in-lake water quality responses were simulated using the BATHTUB model.
TMDL Loading Capacity = E WLA + E LA + MOS
The LC, expressed as the allowable annual average, which is more useful than the daily load for water quality
assessment and watershed planning and management, is as follows:
LC for TP S WLA (15,220 Ib-TP/year) + S LA (118,287 Ib-TP/year) + MOS (14,834 ib-TP/year)
148,341 lb-TP year
LC for TN E WLA (81,432 Ib-TN/year) +1 LA (525,962 Ib-TN/year) + MOS (67,488 Ib-TN/year)
674,882 Ib-TN year
To translate the long-term allowable average growing season loads to maximum daily loads, the KDHE used an
EPA-supported approach described in the Technical Support Document for Water Quality Based Toxics Control:
Maximum Daily Load = (Long-Term Average Load) * eI2'a~0-5oA2 1
where:
o2 ln(CI/2+I)
CV - Coefficient of variation = Standard Deviation / Mean
Z 2.326 for 99th percentile probability basis
TMDL for TP - LC £ WLA (42 lb-TP/day) + £ LA (653 Ib-TP/day) + MOS (77 Ib-TP/day) = 772 lb-TP day
TMDL for TN - LC E WLA (223 Ib-TN/day) +1 LA (2356 Ib-TN/day) + MOS (287 Ib-TN/day)
- 2866 lb-TN'day
The EPA concurs that meeting the TMDL targets will result in the attainment of water quality standards for
Milford Lake.
Designated Use(s), Applicable Water Quality Standard(s) and Numeric Target(s)
The submittal describes applicable water quality standards, including beneficial uses, applicable numeric and/or
narrative criteria, and a numeric target. If the TMDL (s) is based on a target other than a mimetic water quality
critei ion, then a numeric expression, site specific if possible, was developedfrom a narrative criterion and a
description of the process used to derive the target is included in the submittal
Milford Lake Designated Uses; Expected Aquatic Life; Primary Contact Recreation Class A; Domestic Water
Supply: Food Procurement; Ground Water Recharge; Industrial Water Supply; Irrigation and Livestock Watering.
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Water Quality Criteria:
The introduction of plant nutrients into streams, lakes, or wetlands from artificial sources shall be controlled to
prevent the accelerated succession or replacement of aquatic biota or the production of undesirable quantities or
kinds of aquatic life (K.A.R. 28-I6-28e(c)(2)(A)).
The introduction of plant nutrients into surface waters designated for domestic water supply use shall be
controlled to prevent interference with the production of drinking water (K.A.R, 28-16-28e(c)(3)(D)).
The introduction of plant nutrients into surface waters designated for primary or secondary contact recreational
use shall be controlled to prevent the development of objectionable concentrations of algae or algal by-products
or nuisance growths of submersed, floating, or emergent aquatic vegetation (K.A.R. 28-26-28e(c)(7)(A)).
The concentration of dissolved oxygen in surface waters shall not be lowered by the influence of artificial sources
of pollution. The Dissolved Oxygen criterion is 5 milligrams per liter (K.A.R. 28-16-28e(d), Table ig).
A chlorophyll a endpoint of 10 pg/L is the statewide goal for federal lakes and lakes serving as public water
supplies. The target to support primary contact recreation arid all other uses of Milford Lake will be to maintain
average summer chlorophyll a concentrations below 10 micrograms per liter.
Attaining the chlorophyll a endpoint will also result in dissolved oxygen concentrations meeting or exceeding 5
mg/L throughout the water column of the lake. Expected aquatic life support and all other uses have been
considered and are protected at the 5.0 milligrams per liter numeric dissolved oxygen target.
PoUutant(s) of Concern
A statement thai the relationship is either directly related to a numeric water qualify standard, or established using
surrogates and translations to a narrative WQS is included. An explanation and analytical basis far expressing the
TMDL(s) through surrogate measures, or by translating a narrative water quality standard to a numeric target is
provided (e.g.. parameters such as percent fines and turbidity for sediment impairments, or chlorophyll-a and
phosphorus loadings for excess algae). For each identified pollutant, the submittal describes analytical basis for
conclusions, allocations and a margin of safety that do not exceed the loading capacity. If the submittal is a
revised TMDL document, there are refined relationships linking the load to water quality standard attainment. If
there is an increase in the TMDl.(s). there is a refined relationship specified to validate that increase {either had
allocation or wasteload allocation). This section will compare and validate the change in targeted load between
the versions.
There is an established link between the narrative water quality standards for nutrients and numeric total nitrogen
and total phosphorus targets. In eutrophication impairments, chlorophyll a concentrations are used as a translator
in measuring algal growth and the extent of nutrient enrichment and excursions of narrative WQS. Excess
phosphorus and nitrogen enters surface waters and results in eutrophication stimulating blooms of algae and
undesirable weeds. As the biomass respires, dissolved oxygen in the water column fluctuates and may result in
excursions of the WQS for dissolved oxygen. Decomposition of dead algae and other plant material also lowers
the dissolved oxygen concentrations in the lake.
The ratio of total nitrogen to total phosphorus is commonly used to determine which nutrient is limiting plant
growth in Kansas aquatic ecosystems. Typically, lakes that are nitrogen limited have a water column TN;TP ratio
less than 8; lakes that are co-limited by nitrogen and phosphorus have a TN:TP ratio between 9 and 21; and lakes
that are phosphorus limited have a water column TN:TP ratio greater than 21. Milford Lake has varied between
being co-limited by phosphorus and nitrogen (in 1994, 1997, 1998, 2000, 2008 and 2011 surveys) and being
limited by only nitrogen (in 1996, 2001,'2002, 2003, 2004, 2005, 2006, 2009, 2010 and 2012 surveys). During
either limitation, the chlorophyll a concentrations within the main basin of the lake exceeded the 10 micrograms
per liter target established by the KDHE, and therefore both total phosphorus and total nitrogen allocations
are established in the TMDL. document. The TN, TP and the chlorophyll a endpoint are established translators of
the narrative nutrient water quality standards and criteria.
As described on pages 23-24 of the TMDL document, total nitrogen and total phosphorus loads were modeled
using BATHTUB to determine load allocations needed to meet the numeric target of 10 ng/L chlorophyll a,
and to meet the dissolved oxygen criterion of 5 milligrams per liter. The numeric DO target criterion directly
relates to attaining the aquatic life designated use of Milford Lake protected by Kansas' WQS.
The BATHTUB model is an empirical receiving water quality model developed by the U.S. Army Corps of
Engineers, and it has been widely used to establish numeric TMDLs for morphometrically complex lakes and
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reservoirs. The BATHTUB model was utilized for the eutrophication assessment of Milford Lake and for the
development of TMDLs. Milford Lake was subdivided into five segments for BATHTUB modeling, which
includes the riverine, upper pool (transitional area), middle pool (transitional area), main basin and a cove area
near the main basin. Water quality data from the main basin segment was averaged using the KDHE and the
USAGE data from 2008-2012. Data associated with riverine and mid-pool were collected only by the USAGE
from 2008-2012, Model input data for the lake inflow from the Republican River were estimated using the
USACE's FLUX calculator, utilizing the KDHE monitoring data from station SC503 and the U.S. Geological
Survey flow data from gage 06856600 on the Republican River near Clay Center. Inflowing TP and TN
concentrations in un monitored tributaries flowing into the lake were estimated utilizing data from station SC711
and flows derived from USGS estimates. Atmospheric total nitrogen was obtained from the Clean Air Status and
Trends Network, which is available at www.epa.uov/castnet. The CASTNET station from the Konza Prairie was
utilized to estimate the atmospheric TN concentration for the model. Total Phosphorus atmospheric loading was
estimated using a 1983 study.
Based on the BATHTUB model results, total phosphorus and total nitrogen stream concentrations entering the
lake must be reduced by 88 percent. These reductions at the inflow will result in a 71 percent reduction of TP, 75
percent reduction of TN and a 88 percent reduction and the attainment of the 10 jig/L endpoint for chlorophyll
a within the lake. Attainment of the endpoint indicates TP and TN loads are within the loading capacities for the
lake, and the narrative nutrient and numeric DO WQS and criteria are met.
Source Analysis
Important assumptions made in developing the TMDL document, such as assumed distribution of land use in the
watershed, population characteristics, wildlife resources and other relevant information affecting the
characterization of the pollutant of concern and its allocation to sources, are described. Point, nonpoint and
background sources ofpollutants of concern are describedincluding magnitude and location of the sources. The
submittal demonstrates all significant sources haiv been considered, If this is a revised TMDL document any new
sources or removed sources will be specified and explained.
In the absence of a national pollutant discharge elimination system permit, the discharges associated with sources
were applied to the load allocation, as opposed to the wasteload allocation for purposes of this TMDL document.
The decision to allocate these sources to the LA does not reflect any determination by the EPA as to whether these
discharges are, in fact, unpermitted point source discharges within this watershed, hi addition, by establishing
these TMDL(s) with some sources treated as LAs, the EPA is not determining that these discharges are exempt
from NPDES permitting requirements if sources of the allocated pollutant in this TMDL document are found to
he, or become, NPDES-regalated discharges, their toads must be considered as part of the calculated sum of the
IVLAs in this TMDL document. Any WLA in addition to that allocated here is not available.
The predominant land uses in the Milford Lake watershed include 50,3 percent cropland, 37.05 percent grassland.
4,54 percent forest and 4.04 percent roadways. These and the remaining land use percentages and acres for the
watershed were summarized from the 2001 National Land Cover Database and included in Table 18 of the
TMDL document.
Contributing Runoff; The watershed of Milford Lake has a mean soil permeability of 1,16 inches/hour. About
65 percent ofthe watershed has a permeability value less than 1.14 inches/hour, which contributes to runoff
during very low rainfall intensity events. Over 95 percent of the watershed has a permeability value less than 1.29
inches/hour. Runoff is primarily generated when rainfall intensities are greater than soil permeability. As the
watershed's soil profiles become saturated, excess overland flow is produced.
Water Diversions: There are 2,308 unique points of diversion in the five counties within the watershed. The
leading use of water in Riley County is municipal use, and irrigation is the leading use for all other counties
within the watershed, Geary and Jewell Counties have the fewest points of diversions and Clay, Cloud.
Washington and Republic all have the highest number of points of diversions as seen in Table 17 of the TMDL
document. Figure 19 of the TMDL document shows that the majority of the points of diversion all are in close
proximity to the Republican River or its tributaries.
Background: Phosphorus is naturally found in rocks, soil and organic material and is essential for the growth of
aquatic and terrestrial vegetation including agricultural crops. The natural erosion of soil contributes to
the background phosphorus and nitrogen which becomes available to the ecosystem. However, human activities
and practices may cause excessive erosion during runoff events within the watershed and contribute to higher
levels of sediment and attached nutrients. Land use impacts such as the removal of riparian forests and wetlands,
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streambank erosion, urbanization and agricultural activities, including manure and commercial fertilizer
application to cropland, may significantly increase the levels of total phosphorus and nitrogen reaching aquatic
ecosystems. The levels of phosphorus and nitrogen in watershed streams have been significantly increased due to
human activities, land use changes and practices, and therefore it is difficult to estimate the actual background
phosphorus concentrations within the Milford Lake watershed. The atmospheric deposition of nutrients on the
watershed contribute a relatively small amount of the nutrient load. Wildlife inhabitants of the watershed,
particularly in areas near the lake and stream corridors, may contribute to the nutrient load in the watershed;
however, the nutrient contribution of wildlife is considered insignificant.
Internal Loading: Nutrients bound to soil particles in the inflow to Milford Lake are potentially significant
sources of nutrients initially residing in the sediment layer of the lake. Sediment bound nutrients can be released
and re-suspended and continue to add to the eutrophication of Milford Lake. Internal loading of nutrients is a
complex function of lake chemical and biological conditions, lake morphometry and sediment nutrient
availability.
Population Density: According to the 2010 census data from the U.S. Census Bureau, the population of the
entire watershed is approximately 21,291 people, and therefore the population density for the watershed is
approximately 9.73 people/square mile. There are numerous municipalities within the watershed that are detailed
in Table 14 of the TMDL document and account for 18,032 people within the watershed. The population trends
for the majority of the cities within the watershed indicate stable or declining populations. The cities of
Wakefield, Milford and Palmer are the only three cities within the watershed with increased population between
the 2000 and 2010 Census; the city of Wakefield experienced the highest growth rate.
Gn-Site Waste Treatment Systems: Households outside of the municipalities that operate a wastewater
treatment facility are presumably utilizing on-site septic systems. There are approximately 18,032 people living
within the municipalities served by wastewater treatment facilities within the watershed, and therefore there are
approximately 3,259 people within the watershed utilizing on-site septic systems. Significant nutrient loading
may occur if a system fails and it is located near a stream. However, based on the size of this watershed it is
likely that on-site septic systems are an insignificant source contributing to the impairment within the Milford
Lake watershed.
Point Sources: There are 44 permitted facilities within the Milford Lake watershed. The National Pollutant
Discharge Elimination System facilities within the Milford Lake watershed are listed in Appendix D of the
TMDL document. Of these facilities, there are 17 that are non-discharging facilities and 26 permitted discharging
facilities. Of the discharging facilities, there are 11 permitted municipal facilities and 15 industrial facilities. Of
the discharging facilities, there are 9 permits that require nutrient monitoring since they may be sources and
contributors to the impairments of Milford Lake. These facilities along with their average discharge flow, average
effluent total phosphorus concentration and their average effluent total nitrogen concentrations are listed in Table
12 of the TMDL document.
The non-overflowing permitted facilities are prohibited from discharging, but potentially contribute a nutrient
load under extreme precipitation or flooding events. Such events and overflows don't occur frequently, and are
not considered to be a significant contributor to the causes of impairment of Milford Lake.
Livestock Waste Management Systems: There are 184 certified or permitted concentrated animal feeding
operations within the Milford Lake watershed. Facilities and permit numbers are tabulated in Appendix C of the
TMDL document. Although the total potential number of animals is approximately 286,571 head in the
watershed, the actual number of animals at the feedlot operations is typically less than the allowable permitted
number. All of these livestock facilities have waste management systems designed to minimize runoff entering
their operation and detain runoff emanating from their facilities. These facilities are designed to retain a 25-year,
24-hour rainfall runoff event as well as an anticipated two weeks of normal wastewater from their operations.
According to Kansas Agricultural Statistics the estimated number of all cattle, calves and hogs for counties that
are within the watershed as of January 1,2010, and 2011 are detailed in Table 15 of the TMDL document. The
animal waste from both confined and unconfined feeding sites is considered a possible major source of nutrient
loading into Milford Lake. Of particular concern are lands near the riparian areas that are subject to livestock
grazing or watering and fertilizer applications.
Any concentrated animal feeding operation that does not obtain an NPDES permit must operate as a no discharge
operation. Any discharge from an unpermitted CAFO is a violation of Section 301 of the Clean Water Act. It is
the EPA's position that all CAFOs should obtain an NPDES permit because it provides clarity of compliance
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requirements, authorization to discharge when the discharges are the result of large precipitation events such as in
excess of the 25-year and 24-hour frequency/duration event or are from a man-made conveyance.
Any NPDES-permitted CAFOs identified in this TMDL document are part of the assigned wasteload allocation.
Animal feeding operations and unpermitted CAFOs are considered under the load allocation because there is
currently not enough detailed information to know whether these facilities are required to obtain NPDES permits.
This TMDL document does not reflect a determination by the EPA that such a facility does not meet the
definition of a CAFO nor that the facility does not need to obtain a permit. To the contrary, a CAFO that
discharges or proposes to discharge has a duty to obtain a permit. If it is determined that any such operation is a
CAFO that discharges, any future WLA assigned to the facility must not result in an exceedance of the sum of the
WLAs in this TMDL document as approved.
As submitted, the TMDL document has a complete listing of all known sources of pollutant causes of
impairment.
Allocation - Loading Capacity
The submittal identifies appropriate loading capacities, wasteload allocations for point sources and had
allocations for mnpoint sources. If no point sources are present, the WLA is stated as zero. If no nonpoint sources
are present, the LA is stated as zero [40 CFR § I30.2(i)]. If this is a revised TMDL document the change in
loading capacity will be documented in this section. All TMDLs mast give a daily number- Establishing
TMDL "daily" loads consistent with the U.S. Court of Appeals for the D.C. circuit decision in Friends of the
Earth, Inc. v. EPA, et al„ No. 05-5015, (April 25, 2006).
Since Milford Lake has varied between being co-limited by phosphorus and nitrogen and being limited by only
nitrogen, and Chlorophyll a concentrations within the main basin of the lake have been greater than 10
micrograms per liter during either limitation, allocations are established in the TMDL document for both total
phosphorus and total nitrogen.
The BATHTUB model was calibrated for the area-weighted mean of the nutrient data per the EPA's guidance.
The model results estimate that the lake currently retains 75 percent of the total phosphorus and 52 percent of
the total nitrogen load annually. Based on the modeling results, an 88 percent reduction of the TP and TN
concentrations within the stream inflows of the lake are necessary to meet the TMDLs.
A summary of the Milford Lake TMDL document's load allocations are listed in Table 19 of the TMDL
document as follows:
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' >v. ip'-uiKh ;u r d;iy»
Phosphorus Atmospheric 1381.9 7.23
Load Allocation
Phosphorus Nonpoint 116,897.6 646.04
Source Load Allocation
Phosphorus Wasteload 15,220.5 41.7
Allocation
Phosphorus Margin 14,334,1 77.22
of Safety
Phosphorus TMDL 148,341.2
Nitrogen Atmospheric Load 96,807.1 411.]
Allocation
Nitrogen Nonpoint Source 429,155.4 1945.1
Load Allocation
Nitrogen Wasteload 81,431.5 223.1
Allocation
Nitrogen Margin of Safety 67,488.2 286.6
Nitrogen TMDL 674,882.2 2865,9
Wasteload Allocation Comment
The submittal lists individual wasteload allocations for each identified point source [40 CFR § 130.2(h)], If a WLA
is not assigned it must be shown that the discharge does not cause or contribute to a water quality
standard excursion, (he source is contained in a general permit addressed by the TMDL, or extenuating
circumstances exist which prevent assignment of individual WLA. Arty such exceptions must be explained to a
satisfactory degree. If a WLA of zero is assigned to any facility it must be stated as such [40 CFR § 130.2(1)]. If
this is a revised TMDL document, any differences between the original TMDLfs) WLA and the revised WLA will be
documented in this section.
Wasteload allocations are established for the discharging wastewater treatment facilities permitted within the
watershed. There are thirteen facilities that have been assigned a WLA, of which two are industrial facilities and
eleven are municipal facilities. Of these, the largest wasteload allocations are associated with the cities of
Concordia, Clay Center and Belleville. Wasteload allocations for mechanical plants have been assigned based on
an annual average discharge concentration of 1.5 milligrams per liter total phosphorus and 8 mg/L total nitrogen
at their respective design flows. The facilities that have not monitored nutients utilize lagoon systems, and have
been assigned an annual average discharge concentration of 2.0 nig L of TP and S.O mg/L of TN, which are
concentrations typically observed in the effluent of lagoon systems in Kansas. The Nesika Energy facility
discharges low concentrations of TP, and their WLA has been based on a TP concentration of 0.5 mg/L. The
Valley Fertilizer industrial facility has been assigned a WLA for nitrate nitrogen based on the domestic waters
supply use water quality standard of 10 mg/L. The wasteload allocations for Milford Lake are 41.7 pounds per
day of TP and 223.1 lb/day of TN, The discharging facilities with an assigned WLA are detailed in Table 18 of
the TMDL document. All other permitted facilities in the watershed are not contributing to the impairment within
the Milford Lake watershed and have been assigned a WLA of 0 lb day.
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Load Allocation Comment
All nonpoint source hack, natural background and potential for future growth are included if no nonpoin!
sources are identified, the load allocation must he given as zero [40 CFR § } 30.2(g)], If fhis is a revised TMDL
document, any differences between the original TMDL(s) LA and the wised LA will be documented in this section
Nonpoint sources are the main contributor of the nutrient input and impairment of Milford Lake. The monitoring,
modeling and assessment indicate that nutrient loads associated with livestock operations, pastures, and
cultivated crops contribute to the eutrophic condition of Milford Lake. Atmospheric deposition of nutrients is
also considered a nonpoint source. Background and internal loading may be attributed to wildlife, leaf litter
and nutrient cycling from in-Iake sediments. Allowable nutrient load allocations for Milford Lake were calculated
using the BATHTUB model, and the results are a total phosphorous nonpoint source LA of 118,286.5 pounds per
year (653,27pounds per day), and a total nitrogen HPS LA of 525,962.5 lb yr (1346.2 lb day).
Margin of Safety
The submittal describes explicit and'or implicit margins of safety for each pollutant [40 CFR § 130,7(c)(1)], if the
MOS is implicit, the consen-ative assumptions in (he analysis for the MOS are described. If the MOS is explicit, the
loadings set aside for the MOS are identified and a rationale for selecting the value far the MOS is provided. If
this is a revised TMDL document, any differences in the MOS will he documented in this section.
The margin of safety provides some hedge against the uncertainty of variable annual available phosphorus and
nitrogen loads along with the chlorophyll a endpoint. Therefore, the MOS is explicitly set at 10 percent of the
total allocations for the available phosphorus and nitrogen, which compensates for the lack of certainty about the
relationship between the allocated loadings and the resulting water quality response. The margin of safety for
available phosphorus and nitrogen is 77.22 pounds per day and 286.6 lb day, respectively-
Seasonal Variation and Critical Conditions
The submittal describes the methodfor accounting for seasonal variation and critical conditions in the TMDL(s)
[40 CFR § 130,7 (c)(1)]. Critical conditions are factors such as flow or temperature which may lead to the
excursion of the tVQS if this is a re\-ised TMDL document, any differences in conditions will be documented in tlm
section.
Seasonal variation has been incorporated into this TMDL document since the peaks of algal growth occur in the
summer months and the monitoring data that the TMDLs are based upon were collected seasonally. Excursions
from the 5 milligrams per liter dissolved oxygen criterion may be attributed to warm weather as well, which
supports higher microbial respiration in the lake water column and/or sediment. Decomposition of dead algae and
other plant material may lower the dissolved oxygen concentrations near the bottom of the lake.
Public Participation
The submittal describes required public notice and public comment opportunities, and explains how the public
comments were considered in the final TMDL(s) [40 CFR f 130. ~(ci(i)(ii}].
Basin Advisory Committee: The Kansas Lower Republican Basin Advisory Committee met to discuss the
TMDLs of the basin on March 17. 2011, in Manhattan, June 16, 2011, in Lawrence, September 29, 2011, in
Topeka and October 16, 2013, in Manhattan.
Public Notice: An active internet website was established at hi'.p n'.\kdh>k.- »,tn "ij'di index .htm to convey
information to the public on the general establishment of TMDLs and specific TMDLs for the Kansas Lower
Republican Basin.
Public Hearing; A Public Hearing on the Kansas Lower Republican TMDLs was held on December 11, 2013 in
Junction City to receive comments on this TMDL document.
A comment letter was received from the Friends of the Kaw. The letter was supportive of the TMDL document
and noted the need to develop numeric criteria for phosphorus and nitrogen. The KDHE responded to the letter,
but no revisions to the TMDL document were necessary.
Monitoring Plan for TMDL(s) Under a Phased Approach
The TMDL identifies a monitoring plan that describes the additional data to be collected to determine if the toad
reductions required by the TMDL lead to attainment of water quality standards, and a schedule for considering
revisions to the TMDLfs) (where a phased approach is used) [40 CFR § 130.7], If this is a revised TMDL
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document, monitoring to support the revision will be documented in this section. Although the EPA does not
approve the monitoring plan submitted by the stale, the EPA acknowledges the state's efforts. The EPA
understands that the state may me the monitoring plan to gauge the effectiveness of the TMDLs and determine if
future revisions are necessary or appropriate to meet applicable water quality standards.
The KDHE will continue to collect samples every three years from Milford Lake in order to assess the trophic
state, with the next round of sampling to be conducted in 2015. Monitoring will also continue at the KDHE
stream monitoring stations within the watershed to assess the nutrient load contributions from the respective
monitoring stations. The Kansas City Corps of Engineers Office will continue to collect samples in Milford Lake
on a monthly basis between April and October. Additionally, tracking the nutrient loads from point sources
should be done to determine their contributions to the watershed and lake. The expected improved status of
Milford Lake will be evaluated in 2019.
The KDHE expects to evaluate Milford Lake based on monitoring data collected from 2013-2021 and will
reassess the lake in the preparation of the 2024 Integrated Report and § 303(d) list. Should revisions be made to
the applicable water quality criteria for Milford Lake during the implementation period and evaluation for
delisting, desired endpoints of this TM DL document and implementation activities might be amended.
The year 2019 marks the next cycle of 303(d) activities in the Kansas Lower Republican Basin to review data in
the Milford Lake watershed to assess conditions and develop necessary instream phosphorus TMDLs in the
Republican River and its tributaries. Should the impairment in the lake continue, adjustments to the source
assessment, allocations and implementation activities may occur through the TMDL developed for
streams within the watershed.
Reasonable Assurance
Reasonable assurance only applies when less stringent wasteload allocation are assigned based on the
assumption that nonpoint source reductions in the had allocation will be met [40 CFR § I30.2(i)j. This section
can also contain statements made by the state concerning the state's authority to control pollutant loads. States
are not required under Section 303(d) of the Clean Water Act to develop TMDL implementation plans and the EPA
does not approve or disapprove them. However, this TMDL document provides information regarding how point
and nonpoint sources can or should be controlled to ensure implementation efforts achieve the loading reductions
identified in this TMDL document. The EPA recognizes that technical guidance and support are critical to
determining the feasibility? of and achieving the goals outlined in this TMDL document. Therefore, the discussion
of reduction efforts relating to point and nonpoint sources can be found in the implementation section of the TMDL
document, and are briefly described below.
The states have the authority to issue and enforce stale operating permits. Inclusion of effluent limits into a stale
operating permit and requiring that effluent and instream monitoring be reported to the state should provide
reasonable assurance that instream water quality standards will he met. Section 301(b)(1)(C) requires that point
source permits have effluent limits as stringent as necessary to meet IYQS. However, for wasteload allocations to
serve that purpose, they must themselves be stringent enough so that (in conjunction with the water both' "s other
loadings) they meet WQS, This generally occurs when the TMDL(s)' combined nonpoint source had allocations
and point source WLAs do not exceed the WQS-based loading capacity and there is reasonable assurance that the
TMDL(s)" allocations can he achieved. Discussion of reduction efforts relating to nonpoint sources can be found in
the implementation section of the TMDL document.
The following authorities may be used to direct activities in the watershed to reduce pollution;
1. K.S.A. 65-184 and 165 empowers the Secretary of the KDHE to regulate the discharge of sewage
into the waters of the state.
2, K.S.A. 85-171 d empowers the Secretary of the KDHE to prevent water pollution and to protect the
beneficial uses of the waters of the state through required treatment of sewage and established water
quality standards and to require permits by persons having a potential to discharge pollutants into the
waters of the state.
3. K.S.A. 2002 Stipp, 82a-200! identifies the classes of recreation use and defines impairment for
streams.
4, K.A.R 28-16-89 through 71 implements water quality protection by the KDHE through the
establishment and administration of critical water quality management areas on a watershed basis.
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5. K.S.A. 2-1915 empowers the Division of Conservation to develop programs to assist the protection,
conservation and management of soil and water resources in the state, including riparian areas.
6. K.S.A. 75-565? empowers the Division of Conservation to provide financial assistance for local
project work plans developed to control nonpoint source pollution.
7. K.S.A. 82a-901, et. seq. empowers the Kansas Water Office to develop a state water plan directing
the protection and maintenance of surface water quality for the waters of the state.
8. K.S.A. 82a-951 creates the State Water Plan Fund to finance the implementation of the Kansas Water
Plan, including selected Watershed Restoration and Protection Strategies.
9. The Kansas Water Plan and the Kansas Lower Republican River Basin Plan provide the guidance to
state agencies to coordinate programs intent on protecting water quality and to target those programs to
geographic areas of the state for high priority in implementation.
10. K.S.A. 32-807 authorized the Kansas Department of Wildlife and Parks to manage lake resources.
Funding: The State Water Plan Fund annually generates S16-18 million and is the primary funding mechanism
for implementing water quality protection and pollution reduction activities in the state through the Kansas Water
Plan. The state water planning process, overseen by the Kansas Water Office, coordinates and directs programs
and funding toward watersheds and water resources of highest priority. Typically, the state allocates at least 50
percent of the fund to programs supporting water quality protection through the WRAPS program. This
watershed and its TMDLs are a high priority consideration for funding.
Desired Implementation activities for agriculture:
1. Implement soil sampling to recommend appropriate fertilizer applications on cultivated croplands to
ensure excess nutrients are not being applied.
2. Maintain conservation tillage and contour farming to minimize cropland erosion.
3. Promote and adopt continuous no-till cultivation to increase the amount of water infiltration and
minimize cropland soil erosion and nutrient transports,
4. Install grass buffer strips along streams and drainage channels in the watershed.
5. Reduce land disturbance activities within riparian areas.
6. Implement nutrient management plans to manage manure land applications and runoff potential,
7. Adequately manage fertilizer utilization in the watershed and implement runoff control measures.
i. Install pasture management practices, including proper stock density to reduce soil erosion and storm
runoff.
9. Renew state and federal permits and inspect permitted facilities for permit compliance.
10. Utilize state-supported Milford Lake WRAPS process to coordinate load reduction of nutrients to the
lake.
Nutrient control in Kansas watersheds has been proven effective through conservation tillage, contour farming
and use of grass waterways and buffer strips, in addition, the proper implementation of comprehensive livestock
waste management plans has proven effective at reducing nutrient runoff associated with livestock facilities. The
key to success will be widespread utilization of conservation farming and proper livestock waste management
systems within the Milford Lake watershed.
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