Loading Analysis Plan and Supporting Data Acquisition Needed for the Tenmile Creek and the Ottawa River Watersheds Fulton and Lucas Counties, Total Maximum Daily Load Development

Hill Ditch near mouth, Ottawa River (Toledo) basin.

Ohio EPA Technical Report AMS/2011-OTTEN-3 Division of Surface Water Assessment and Modeling Section March 2019 TMDL DEVELOPMENT |

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Introduction This document provides an overview of the information considered in proposing analytical methods to address water quality impairments in the Tenmile Creek and Ottawa River watershed (Fulton and Lucas Counties, Ohio). These recommendations are based on data collected as part of a biological and water quality study in 2011. A description of the project area, sites, data types and methods can be found in the Tenmile Creek and Ottawa River study plan document at (https://epa.ohio.gov/portals/35/tmdl/TenmileStudyPlan2011_Final.pdf). A summary of the study results can be found in the biological and water quality report at (https://epa.ohio.gov/Portals/35/documents/Tenmile_Ottawa_TSD_2015.pdf).

Sites in the Tenmile Creek and Ottawa River watershed were assessed for aquatic life use and recreation use. The public water supply use was not assessed since no surface waters are used as a public water supply in this study area. The attainment of aquatic life and recreation use is based on specific restoration targets. This document examines those targets and lays out proposals for addressing each impairment. Where appropriate, methods are outlined to develop total maximum daily loads (TMDL) for specific pollutants. Aquatic Life Use Evaluation of Biocriteria Attainment of Ohio EPA’s biocriteria are based on fish and macroinvertebrate scores, as measured by the Index of Biotic Integrity (IBI), Modified Index of well-being (MIwb) and Invertebrate Community Index (ICI). Goals for those indices in the Tenmile Creek and Ottawa River watershed are shown in Table 1. The attainment status for each site is shown in Figure 1 and the scores for impaired sites are shown in Table 2.

Table 1 – Biological criteria applicable in the Ottawa River (Toledo) watershed for aquatic life use designations.

Biological Criteria for the Biological Assessment Applicable Aquatic Life Use Ecoregion Index Method2, 3 Designations1 WWH MWH4 Headwater 28 20 IBI Wading 32 22 Huron-Erie Boat 34 20 / 22 Lake Plains Wading 7.3 5.6 (HELP) MIwb Boat 8.6 5.7 / 5.7 ICI All5 34 22 1 Aquatic Life Use (ALU) designations: warmwater habitat (WWH); modified warmwater habitat (MWH); limited resource waters (LRW) and seasonal salmonid habitat (SSH) do not have associated biological criteria. 2 The assessment method used at a site is determined by its drainage area (DA) according to the following: Headwater: DA ≤ 20 mi2; wading: DA >20 mi2 and ≤ 500 mi2; boat: DA > 500 mi2. 3 MIwb not applicable to drainage areas less than 20 mi2 (headwater sites). 4 Biocriteria depend on type of MWH. MWH-C (due to channelization) is listed first and MWH-I (due to impoundment) is listed second. 5 Limited to sites with appropriate conditions for artificial substrate placement.

2

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Figure 1 — Map summarizing ALU attainment status in the Tenmile Creek and Ottawa River watershed in 2011.

3

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Table 2 – Aquatic life use attainment information for impaired sampling locations in the Tenmile Creek and Ottawa River watershed, 2011. Shaded sites are in the Maumee Area of Concern.

Drain. Ecoregion/ River Attain. Station Location Area IBI MIwbc ICId QHEI Causes Sources ALU Milea Status (mi2) 04100002 03 04 - Little Bear Creek-Bear Creek Bear Creek near Ohio/ 301452 border HELP/ WWH 8.44 22.90 26.0 7.82 38.0 31.5 NON Sedimentation/ siltation Channelization @Fulton County Rd. 7 04100001 03 01 – Shantee Creek Shantee Creek Urban runoff/storm P11S96 diversion at Toledo @ HELP/ LRW 3.10 7.70 12.0 N/A VP 29.0 NON Sedimentation/siltation sewers Lewis Ave. Sediment resuspension Shantee Creek Priority organics (contaminated P11S60 diversion at Toledo @ HELP/ MWH 0.70 9.10 24.0 N/A LF 35.0 PARTIAL (PCB/PAH in sediments) sediment), Urban Stickney Ave. runoff/storm sewers Silver Creek at Toledo Urban runoff/storm P11S79 HELP/ LRW 4.44 4.60 16.0 N/A P 43.0 NON Sedimentation/siltation @Lewis Ave. sewers Urban runoff/ storm Sedimentation/ siltation sewers Silver Creek at Toledo Sediment resuspension 301449 HELP/ MWH 1.70 5.70 22.0 6.98 VP 41.0 NON @ Futura Dr. Priority Organics (PAH in (contaminated sediments) sediment), Urban runoff/storm sewers 04100001 03 02 – Halfway Creek Urban runoff/ storm Halfway Creek near Sedimentation/ siltation 301448 Ohio/ Michigan border HELP/ WWH 4.88 22.10 36.0 7.96 F 50.0 PARTIAL sewers @ East State Line Rd. Priority Organics sediment resuspension 04100001 03 04 – Headwaters Tenmile Creek Tenmile Creek east of 301446 Metamora @ Fulton HELP/ WWH 16.0 25.90 26.0 7.38 G 32.5 NON Sedimentation/ siltation Channelization County Rd. 1 Tenmile Creek west of P11K65 HELP/ WWH 9.76 43.00 31.0 6.75 G 49.0 PARTIAL Sedimentation/ siltation Channelization Sylvania @ Kilburn Rd. 4

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Drain. Ecoregion/ River Attain. Station Location Area IBI MIwbc ICId QHEI Causes Sources ALU Milea Status (mi2) 04100001 03 05 – North Tenmile Creek North Tenmile Creek Crop production with P11S77 at Sylvania @ Monroe HELP/ WWH 0.12 42.1 28.0 7.89 F 54.0 PARTIAL Low flow alterations subsurface drainage St. 04100001 03 06 – Tenmile Creek Tenmile Creek P11S76 southwest of Sylvania HELP/ WWH 5.94 64.5 34.0 6.98 18.0 52.5 PARTIAL Sedimentation/siltation Channelization @ Herr Rd Tenmile Creek P11K64 southwest of Sylvania HELP/ WWH 2.97 70.0 37.0 6.14 26.0 51.0 PARTIAL Sedimentation/siltation Channelization @ Brint Rd. 04100001 03 07 – Heldman Ditch-Ottawa River Ottawa River near Urban runoff/ storm 301440 Sylvania @ Harroun HELP/ WWH 19.50 124.6 37.0 6.34 34.0 78.0 PARTIAL Sedimentation/siltation sewers Rd. Ottawa River near Urban runoff/ storm 301442 Ottawa Hills @ HELP/ WWH 14.42 131.6 34.0 5.63 28.0 59.3 NON Sedimentation/siltation sewers Edgehill Rd. Zink Ditch west of Urban runoff/ storm P11P37 HELP/ MWH 0.70 3.5 38.0 N/A LF 34.5 PARTIAL Sedimentation/siltation Toledo @ Dorr St. sewers Hill Ditch @ Carriage Urban runoff/ storm 301450 HELP/ MWH 2.58 3.5 22.0 N/A P 64.5 PARTIAL Sedimentation/siltation Dr. sewers Hill Ditch near Ottawa Urban runoff/ storm P11K61 HELP/ MWH 2.11 6.3 22.0 N/A LF 55.0 PARTIAL Sedimentation/siltation Hills @ Reynolds Rd. sewers 04100001 03 08 – Sibley Creek-Ottawa River Ottawa River at Urban runoff/ storm 301444 HELP/ WWH 9.25 155.60 25.0 8.41 24.0 72.0 NON Sedimentation/siltation Toledo @ Monroe St. sewers Ottawa River at Urban runoff/ storm 301443 Toledo @ Douglas HELP/ WWH 10.86 155.0 30.0 6.23 16.0 43.0 PARTIAL Sedimentation/siltation sewers Ave. Ottawa River at Urban runoff/ storm P11S74 Toledo @ University of HELP/WWH 11.15 155.0 33.0 7.13 28.0 48.5 PARTIAL Sedimentation/siltation sewers Toledo

5

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Drain. Ecoregion/ River Attain. Station Location Area IBI MIwbc ICId QHEI Causes Sources ALU Milea Status (mi2) Ottawa River at Urban runoff/ storm P11K59 HELP/ WWH 11.67 154.0 27.0 4.34 22.0 63.0 NON Sedimentation/siltation Toledo @ Secor Rd. sewers 04100001 03 09 – Detwiler Ditch-Frontal Urban runoff/ storm Detwiler Ditch at Sedimentation/siltation P11S84 Toledo @ Detweiler HELP/ MWH 0.5 6.2 31.0 7.22 P 35.0 PARTIAL sewers, Park Priority organics Sediment resuspension a River Mile (RM) represents the Point of Record (POR) for the station and may not be the actual sampling RM. c MIwb is not applicable to headwater streams with drainage areas < 20 mi2. d A narrative evaluation of the qualitative sample based on attributes such as EPT taxa richness, number of sensitive taxa, and community composition was used when quantitative data was not available or considered unreliable. VP=Very Poor; P=Poor; LF=Low Fair; F=Fair; MG=Marginally Good; G=Good; VG=Very Good; E=Exceptional ns Nonsignificant departure from biocriteria (<4 IBI or ICI units, or <0.5 MIwb units). * Indicates significant departure from applicable biocriteria (>4 IBI or ICI units, or >0.5 MIwb units). Underlined scores are in the Poor or Very Poor range. H Headwater site (draining ≤20 miles2). W Wading site (non-boat site draining >20 miles2). B Boat site (large or deep waters, necessitating the use of boat sampling methods)

Proposed Actions Ohio EPA considers many factors when deciding how to address impairments. For some projects, no TMDL is required. The watershed may be in attainment or the impairment is being addressed by another program/entity so no further action by the Division of Surface Water is necessary. Additionally, the cause of impairment may be natural (i.e., flow or habitat), in which case no action is required. For those needing a TMDL, the complexity of each impairment—including the primary origin of the pollutant, its delivery mechanisms and the waterbody kinetics involved—will determine the complexity needed in a model. Additionally, Ohio EPA must take into consideration ongoing efforts in the watershed, previous TMDL analyses, the questions to be answered by a model and the amount of effort required to complete the model. Depending on the method selected, the Agency may be required to return to the watershed and collect additional data, and it is possible the modeling approach may change. A summary of Ohio EPA’s preliminary modeling approaches is presented in Table 3.

Table 3 – Summary of ALU impairments and potential modeling approaches. Shaded rows are within the Maumee Area of Concern.

River Station Stream Name HUC12 Causes Sources Action1 Method1 Milea Sedimentation/ 301452 Bear Creek 8.44 04100002 03 04 Channelization TMDL QHEI-sed siltation

6

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

River Station Stream Name HUC12 Causes Sources Action1 Method1 Milea Urban runoff/storm P11S96 Shantee Creek 3.10 04100001 03 01 Sedimentation/siltation 5-alt 9-element plan sewers Sediment resuspension Priority organics (contaminated P11S60 Shantee Creek 0.70 04100001 03 01 (PCB/PAH in 5-alt Maumee AOC Program sediment), Urban sediments) runoff/storm sewers Urban runoff/storm P11S79 Silver Creek 4.44 04100001 03 01 Sedimentation/siltation 5-alt 9-element plan sewers Sedimentation/ Urban runoff/ storm 5-alt 9-element plan siltation sewers Sediment resuspension 301449 Silver Creek 1.70 04100001 03 01 Priority Organics (contaminated 5-alt Maumee AOC Program (PAH in sediments) sediment), Urban runoff/storm sewers Sedimentation/ Urban runoff/ storm TMDL QHEI-sed siltation sewers 301448 Halfway Creek 4.88 04100001 03 02 sediment resuspension Priority Organics (contaminated 5-alt Maumee AOC Program sediment) Sedimentation/ 301446 Tenmile Creek 16.0 04100001 03 04 Channelization 5-alt 9-element plan siltation Sedimentation/ P11K65 Tenmile Creek 9.76 04100001 03 04 Channelization 5-alt 9-element plan siltation North Tenmile Crop production with P11S77 0.12 04100001 03 05 Low flow alterations Other Revise Listing Creek subsurface drainage P11S76 Tenmile Creek 5.94 04100001 03 06 Sedimentation/siltation Channelization 5-alt 9-element plan P11K64 Tenmile Creek 2.97 04100001 03 06 Sedimentation/siltation Channelization 5-alt 9-element plan Urban runoff/ storm 301440 Ottawa River 19.50 04100001 03 07 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm 301442 Ottawa River 14.42 04100001 03 07 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm P11P37 Zink Ditch 0.70 04100001 03 07 Sedimentation/siltation 5-alt 9-element plan sewers

7

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

River Station Stream Name HUC12 Causes Sources Action1 Method1 Milea Urban runoff/ storm 301450 Hill Ditch 2.58 04100001 03 07 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm P11K61 Hill Ditch 2.11 04100001 03 07 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm 301444 Ottawa River 9.25 04100001 03 08 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm 301443 Ottawa River 10.86 04100001 03 08 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm P11S74 Ottawa River 11.15 04100001 03 08 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm P11K59 Ottawa River 11.67 04100001 03 08 Sedimentation/siltation 5-alt 9-element plan sewers Urban runoff/ storm Sedimentation/siltation 5-alt 9-element plan P11S84 Detwiler Ditch 0.5 04100001 03 09 sewers, Priority organics Sediment resuspension 5-alt Maumee AOC Program a The River mile here refers to the point of record, actual sample may have occurred at a slightly different location. 1 Due to space limitations there are several abbreviations used to describe the analysis or remediation method. Those abbreviations are defined as follows: Abbreviation Definition/interpretation

TMDL A Total Maximum Daily Load (TMDL) will be completed for the impairment. 5-alt Category 5-alternative restoration plan developed to outline approaches more immediately beneficial or practicable than a TMDL. QHEI-sed Sub-metrics of the QHEI used to develop TMDLs using aspects of habitat quality as a surrogate for addressing impairment due to excess sediment. 9-element Plan Nonpoint source implementation strategic (NPS-IS) plans have been developed to address causes and sources of impairment for HUC12 subwatersheds. Based on survey findings, the listing will be updated in a subsequent Integrated Report and a TMDL or other action will not be required (i.e., a category 5 could Revise listing be revised to a category 4c—not a pollutant). Maumee Area of Concern program will address the causes of impairment to achieve beneficial use impairment (BUI) restoration targets related to fish and Maumee AOC Program macroinvertebrate populations and habitat

8

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

The Tenmile Creek and Ottawa River watershed studied in 2011 had two overarching causes of impairment: sedimentation/siltation and priority organics (legacy). These causes are linked to diffuse sources or are pollutants already dispersed into the environment, therefore landscape and channel management practices are required to improve stream conditions and achieve attainment of aquatic life uses. For sedimentation/siltation in the project area, this largely means affecting channel and drainage maintenance activities to improve channel form and function while also reducing upland sources. In the case of priority organics, this includes a combination of dredging alongside identification and mitigation of remaining upland sources.

Of the eleven HUC-12 subwatersheds within the assessment area, eight had sedimentation appear as a cause of impairment. While the cause was extensive, different sources contributed to the cause within the watershed. Tenmile Creek transitions from a rural area dominated by row crop production to an area dominated by suburban development and finally to an urban landscape; mechanisms that affect stream habitat and geomorphology vary across these landscapes. In the rural areas of the watershed, the stream was historically channelized to facilitate drainage and promote agricultural production. Low gradients natural to the area and continued stream maintenance activities limit the ability of the stream to recover its natural channel functions. As the stream transitions to urban areas, impacts from developed land become the driver of sedimentation and siltation. Formal channelization is less common in much of these areas, especially in larger stream reaches, in these areas altered stream hydrology linked to urban runoff and stream hydrology become principal sources of sedimentation/siltation.

Nine-element non-point source implementation strategies (9-element NPS-IS) are developed as strategic planning documents that summarize the causes and sources of impairment, establish critical areas, identify quantifiable objectives to address causes and sources of impairment, and describe projects designed to meet those objectives. Watersheds where causes of impairment are linked to diffuse sources are well suited to development of 9-element NPS-IS in lieu of TMDLs because allocations are less complex. Under this alternative strategy, a TMDL may still be required if the alternative action does not result in progress towards attainment of water quality standards.

Ohio’s Area of Concern (AOC) program evaluates beneficial use impairments (BUIs) differently for the AOC Program than Ohio EPA does, for developing the 303(d) list. However, both programs have identified priority contaminants from legacy sources as problems that need to be addressed. This assessment area, except Bear Creek, is included within the Maumee AOC. The Maumee AOC program has worked with federal, state and local partners to evaluate priority organics/legacy pollutants in the Halfway, Silver and Shantee Creeks within the AOC (Tetra Tech, 2014). The report evaluated the types and locations of priority pollutants, defined critical areas and identified options to address the known toxic pollutants in the watersheds. The Maumee AOC program will pursue these options as funding becomes available to mitigate the impact of priority pollutants on fish and macroinvertebrate communities in the impacted HUCs.

Three HUC-12 subwatersheds will not be addressed via 9-element NPS-IS; sedimentation/siltation on Little Bear Creek, low flow alterations on North Tenmile Creek, and sedimentation/siltation and priority organics on Halfway Creek. The 9-element NPS-IS plans have been developed to identify impaired areas within most of the Maumee AOC. Bear Creek is not within the Maumee AOC; therefore, this effort did not extend into this area. Instead for this impairment, a QHEI-sediment TMDL will be developed. A portion of both the North Tenmile Creek and Halfway Creek HUC-12 subwatersheds are within the AOC, but they are largely in Michigan. Because these watersheds and the associated sources of impairment are largely outside of Ohio’s jurisdiction to oversee projects they were excluded from this Ohio led effort. Low flows in North Tenmile Creek are not a pollutant and therefore a TMDL is not the appropriate strategy to address the cause of impairment, in the absence of an NPS-IS plan this impairment

9

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

will not be addressed. The sedimentation/siltation cause of impairment on Halfway Creek will be addressed with a QHEI-sediment TMDL, however, the priority organics cause will not be addressed with a TMDL because there are no current sources of the pollutant and it is already dispersed into the environment. Remedial actions outside of the TMDL process will continue to address legacy impairments within the AOC.

The final action recommended is to revise the listing for the site assessed on North Tenmile Creek. The cause of impairment is low flow alterations. Flow is not a pollutant so the listing category ‘4c’ is more appropriate, and a TMDL is not required. The listing is linked to nonpoint source activities and there are options to mitigate the influences of cropland drainage of low flow regimes. The nature of this cause is best addressed with a 9-element plan, however, Ohio has no plans to develop a plan or projects because the majority of the HUC-12 is in Michigan and Ohio cannot facilitate projects required for an effective 9-element plan in that area.

Proposed Targets Sediment Since its development, the QHEI has been used to evaluate habitat at most biological sampling sites and there is an extensive database that includes QHEI scores and other water quality variables. Strong correlations exist between QHEI scores and the biological indices used in Ohio’s water quality standards such as the Index of Biotic Integrity (IBI). Through statistical analyses of data for the QHEI and the biological indices, target values have been established for QHEI scores with respect to the various aquatic life use designations (Ohio EPA 1999).

Numeric targets for sediment are based on three sub-metrics of the QHEI. Although the QHEI evaluates the overall quality of stream habitat, some of its component sub-metrics consider particular aspects of stream habitat that are closely related to and/or impacted by the sediment delivery and transport processes occurring in the system. The QHEI sub-metrics used in the sediment TMDL are the substrate, channel morphology, and bank erosion/riparian zone. Table 4 lists targets for each of these metrics.

Table 4 – QHEI targets for sediment TMDLs Sediment TMDL Targets QHEI Category WWH Substrate ≥ 13 Channel ≥ 14 Riparian ≥ 5 Sediment TMDL ► ≥ 32

The substrate sub-metric evaluates predominant substrate types, the amount and origin of these types and the degree of embeddedness and silt cover. This is a qualitative evaluation of the amount of excess fine material in the system and the ability of the channel to assimilate or sort the sediment load.

The channel morphology sub-metric considers sinuosity, riffle and pool development, channelization and channel stability. Except for stability, each of these aspects is directly related to channel form, sediment transport, erosion, and deposition within the channel. Stability reflects the degree of channel erosion, which indicates the potential of the stream channel to be a significant sediment source.

The bank erosion and riparian zone sub-metric also reflects the likely degree of in-stream sediment sources. The evaluation of floodplain quality is included in this sub-metric, which relates to the capacity of the system to assimilate sediment loads. 10

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Recreation Use Evaluation of Criteria Attainment of recreation use goals is based on numeric criteria for Escherichia coli (E. coli) as an indicator bacterium. These criteria, shown in Table 5, are also the targets used for TMDLs. Table 9 lists attainment of recreation use based on criteria at the time of assessment, which were different than the current standards. However, any TMDLs created for those assessment units will use the updated values in Table 8.

Table 5 – Water quality criteria for recreation use Escherichia coli (colony forming units per 100 mL) Recreation Use 90-day geometric mean Statistical threshold value1 Bathing water 126 410a Primary contact recreation 126 410 Secondary contact recreation 1030 1030 1 These criteria shall not be exceeded in more than 10 percent of the samples taken during any ninety-day period. a A beach action value of 235 E. coli colony counts per 100 mL shall be used for the purpose of issuing beach and bathing water advisories.

Table 6 – Recreation use attainment information for impaired sampling locations in the Tenmile Creek and Ottawa River watershed, 2011.

Geometric Maximum Attainment Station Stream Name River Mile # Samples Mean Value Status 04100002 03 04 – Little Bear Creek-Bear Creek 301452 Bear Creek 8.44 5 450 1400 Non 04100001 03 01 – Shantee Creek 301449 Silver Creek 1.74 5 704 5200 Non 04100002 03 02 – Halfway Creek 301448 Halfway Creek 4.88 5 287 1800 Non 04100002 03 03 – Prairie Ditch 301447 Prairie Ditch 1.41 5 190 510 Non 04100002 03 04 – Headwaters Tenmile Creek P11K65 Tenmile Creek 9.17 5 416 1100 Non 04100002 03 05 – North Tenmile Creek North Tenmile P11S77 0.12 5 168 1700 Non Creek 04100002 03 06 – Tenmile Creek P11S76 Tenmile Creek 5.94 11 606 2700 Non P11K63 Tenmile Creek 0.47 5 316 2800 Non 04100002 03 07 – Heldman Ditch-Ottawa River 301440 Ottawa River 19.50 5 325 4400 Non 301441 Ottawa River 16.84 5 315 2000 Non 04100002 03 08 – Sibley Creek-Ottawa River P11S74 Ottawa River 11.15 12 682 6000 Non

11

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Proposed Actions Concentrations of E. coli exceeding the water quality standard are due to both pervasive and direct sources. Two predominant pathways exist for pathogen delivery to water bodies. The first pathway is pathogen-rich discharge, including material such as poorly treated or untreated effluent from wastewater treatment plants, combined sewer overflows, sanitary sewer overflows, household sewage treatment systems and livestock access to streams. This is delivered to the stream by direct discharge. The second pathway is pathogen-rich runoff/drainage from nonpoint sources. The associated delivery mechanism is precipitation-driven wash-off. This type of transport involves the delivery of pathogen-rich material by overland flow during precipitation and runoff events (e.g., summer storms, snowmelt, etc.).

Due to these mechanisms of delivery, the sources of pathogens in surface waters can be determined to a certain extent via the level of stream flow observed. Therefore, Ohio EPA proposes using the load duration curve (LDC) framework for recreation use TMDLs. LDCs are an empirical method of determining TMDL pollutant loading and needed reductions. The main advantage of the use of LDCs is in this method’s ability to differentiate loads from various types of sources based on stream flow regime. While this is a fairly simple modeling method, relationships between bacteria source contributions and flow regimes are straight forward. In-stream processes and interactions between sources are simplified, mitigating the major weaknesses of the technique. Figure 2 shows an example LDC with corresponding TMDL calculations represented in Table 7. Ohio EPA will handle recreation use impairment via LDC TMDLs.

Figure 2 – Example load duration curve.

12

AMS/2011-OTTEN-3 Loading Analysis Plan – Tenmile Creek and Ottawa River Watershed March 2019

Table 7 – Example TMDL table calculations (from above load duration curve).

High Wet weather Normal range Dry weather Low TMDL and duration intervals 0-5% 5-40% 40-80% 80-95% 95-100%

Samples Per Regime 2 4 5 3 2 Median Sample load 66807 781 209.25 7.72 2.99 Total Load Reduction Required 98.9% 82.8% 84.7% NA NA Total Maximum Daily Load 1036.68 182.09 43.25 17.26 8.35 Margin of Safety: 20% 207.34 36.42 8.65 3.45 1.67 Allowance for Future Growth 62.20 10.93 2.60 1.04 0.50 Load Allocation 740.71 127.29 27.63 8.98 2.58 Wasteload Allocation Total 26.43 7.46 4.37 3.80 3.60 MS4 23.01 4.04 0.96 0.38 0.19 Example Town WWTP XPX00XXX 3.41 3.41 3.41 3.41 3.41

References Ohio EPA (Ohio Environmental Protection Agency – Division of Surface Water). 1999. Association between nutrients, habitat, and the aquatic biota of Ohio’s rivers and streams. Published at: epa.ohio.gov/portals/35/guidance/assoc_load.pdf

Ohio EPA (Ohio Environmental Protection Agency – Division of Surface Water). 2000. Legal and Technical Basis for Nutrient Target Values Used in TMDL Projects, Water Quality Standard Guidance 4. Published at: epa.ohio.gov/portals/35/guidance/wqs4.pdf

Tetra Tech. 2014. Halfway, Silver and Shantee Creeks Analysis. Published at: dmds.maumeerap.org/view.cfm?type=resource&id=531

13