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Guidance for meeting dissolved oxygen or oxygen demand TMDL MS4 permit requirements

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This page provides information and guidance for <span title="A municipal separate storm sewer system (MS4) is a means of transportation, individually or in a system, (e.g. roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains, etc.) that are: owned or operated by a public entity (e.g. cities, townships, counties, military bases, hospitals, prison complexes, highway departments, universities, etc.) with jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes. This includes special districts under State law (sewer, flood control, or drainage districts, etc.), an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act; designed or used for collecting or transporting stormwater; not a combined sewer; and not part of a publicly owned treatment works."> '''MS4'''</span> (Municipal Separate Storm Sewer System) permittees who have <span title="the amount of a pollutant from both point and nonpoint sources that a waterbody can receive and still meet water quality standards"> [https://stormwater.pca.state.mn.us/index.php?title=Total_Maximum_Daily_Loads_(TMDLs) '''total maximum daily load''']</span> (TMDLs) <span title="the portion of a receiving water's assimilative capacity that is allocated to one of its existing or future point sources of pollution"> '''wasteload allocations'''</span> (WLAs) for dissolved oxygen or oxygen demand.

==Overview==
The amount of <span title="Dissolved oxygen (DO) is a measure of how much oxygen is dissolved in the water - the amount of oxygen available to living aquatic organisms."> '''dissolved oxygen'''</span> (DO) an aquatic organism needs depends upon species, water temperature, and other factors such as the life stage of an organism. For most [https://www.revisor.mn.gov/rules/7050.0222/ Class 2B waters], the DO standard is 5 mg/L as a daily average and 4 mg/L as a daily minimum. Oxygen demand is a measure of the oxygen used by microorganisms to decompose organic matter. Oxygen demand is expressed either as biochemical oxygen demand (BOD), chemical oxygen demand (COD), or nitrogenous oxygen demand (NOD).
*Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20°C ([https://en.wikipedia.org/wiki/Biochemical_oxygen_demand Wikipedia]).
*Chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution and expressed in milligrams per litre (mg/L) ([https://en.wikipedia.org/wiki/Chemical_oxygen_demand Wikipedia]).
*Carbonaceous biochemical oxygen demand or CBOD is a method defined test measured by the depletion of dissolved oxygen by biological organisms in a body of water in which the contribution from nitrogenous bacteria has been suppressed ([https://en.wikipedia.org/wiki/Carbonaceous_biochemical_oxygen_demand Wikipedia]).
*Nitrogenous oxygen demand (NOD) is a quantitative measure of the amount of dissolved oxygen required for the biological oxidation of nitrogenous material, for example, nitrogen in ammonia, and organic nitrogen in waste water ([https://stats.oecd.org/glossary/detail.asp?ID=1783 Organisation for Economic Co-operation and Development]).
*Total oxygen demand (TOD) defines the total oxygen demand of the water sample.

Waters that have adequate DO under natural conditions but that are impaired for DO typically have one or more <span title="of, relating to, or resulting from the influence of human beings on nature"> '''anthropogenic'''</span> sources of organic matter that create an oxygen demand. For urban stormwater, examples of organic matter sources include leaves and other yard wastes, pet and animal wastes, fertilizer, sediment containing organic matter (e.g. topsoil), and hydrocarbons (e.g. oil). A median value for BOD in stormwater runoff in urban settings is about 8 mg/L, while a median value for COD is about 22 mg/L. These BOD levels are greater than Class 2B <span title="Water quality standards (WQS) are provisions of state, territorial, authorized tribal or federal law approved by EPA that describe the desired condition of a water body and the means by which that condition will be protected or achieved."> '''water quality standards'''</span>, which range from 1.5 to 3.5 depending on geographic location.

==Total Maximum Daily Loads (TMDLs) with BOD or COD wasteload allocations==
Currently there are three approved <span title="the amount of a pollutant from both point and nonpoint sources that a waterbody can receive and still meet water quality standards"> [https://stormwater.pca.state.mn.us/index.php?title=Total_Maximum_Daily_Loads_(TMDLs) '''total maximum daily load''']</span> (TMDLs) - for [https://www.pca.state.mn.us/water/tmdl/hardwood-creek-impaired-biota-fish-and-low-dissolved-oxygen-tmdl-project Hardwood Creek] (Waterbody ID: 07010206-596), [https://www.pca.state.mn.us/sites/default/files/wq-iw8-56e.pdf Trott Brook] (Waterbody ID: 07010207-680), and [https://www.pca.state.mn.us/water/tmdl/buffalo-creek-south-fork-crow-river-bacteria-tmdl-project Buffalo Creek] (Waterbody ID: 07010205-638 (formerly 07010205-501)) - that include <span title="A municipal separate storm sewer system (MS4) is a means of transportation, individually or in a system, (e.g. roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, storm drains, etc.) that are: owned or operated by a public entity (e.g. cities, townships, counties, military bases, hospitals, prison complexes, highway departments, universities, etc.) with jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes. This includes special districts under State law (sewer, flood control, or drainage districts, etc.), an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act; designed or used for collecting or transporting stormwater; not a combined sewer; and not part of a publicly owned treatment works."> '''MS4'''</span> (Municipal Separate Storm Sewer System)<span title="the portion of a receiving water's assimilative capacity that is allocated to one of its existing or future point sources of pollution"> '''wasteload allocations'''</span> (WLAs) for oxygen demand that are not assigned a zero percent reduction. Hardwood Creek is impaired for aquatic life (fish) due to low dissolved oxygen and Trott Brook and Buffalo Creek are impaired for aquatic life (fish and aquatic macroinvertebrates) due to low dissolved oxygen.

{{:MS4s with applicable dissolved oxygen/oxygen demand WLAs}}

==MS4 permit requirement (Permit/Application Section 22.2)==
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<th><center><font size=3>'''What is a compliance schedule?'''</font size></center></th>
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<td>'''A compliance schedule is a a schedule of compliance leading to compliance with Clean Water Act regulations. Compliance schedules must meet the following.'''
*it must be an enforceable sequence of actions or operations leading to compliance with a water quality-based effluent limitation
*it must include an enforceable final effluent limitation and a date for its achievement that is within the timeframe allowed by the applicable State or federal law
*if the date extends past the expiration date of a permit must include the final effluent limitations in the permit
* the permitting authority has to make a reasonable finding, adequately supported by the administrative record, that the compliance schedule “will lead to compliance with an effluent limitation . . . ” “to meet water quality standards” by the end of the compliance schedule
* the permitting authority has to make a reasonable finding that compliance with the final WQBEL is required “as soon as possible.”
* the permitting authority has to make a reasonable finding, adequately supported by the administrative record, that the discharger cannot immediately comply with the WQBEL upon the effective date of the permit
*[https://www.epa.gov/sites/production/files/2015-09/documents/memo_complianceschedules_may07.pdf Link to EPA guidance on compliance schedules]
</td>
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Sections 22.1 and 12.8 of the MS4 permit provides the requirements for permittees who have a TMDL WLA for dissolved oxygen or oxygen demand.

'''Section 22.1''': ''If the permittee has an applicable WLA for dissolved oxygen or oxygen demand, nitrate, TSS, and TP, the permittee must provide a summary of the permittee's progress toward achieving applicable WLAs for dissolved oxygen or oxygen demand, nitrate, TSS, and TP with the annual report required in item 25.3. The summary must include the following information:''<br>
''a. a list of all BMPs applied towards achieving applicable WLAs for dissolved oxygen or oxygen demand, nitrate, TSS, and TP;''<br>
''b. the implementation status of BMPs included in the compliance schedule at the time of final application submittal; and''<br>
''c. an updated estimate of cumulative TSS and TP load reductions.''

'''Section 12.8''': ''The applicant must submit a compliance schedule for each applicable Waste Load Allocation (WLA) not being met for dissolved oxygen or oxygen demand, nitrate, total suspended solids (TSS), and total phosphorus (TP). The applicant may develop a compliance schedule to include multiple WLAs. The applicant's compliance schedule must include the following information:''
''a. proposed BMPs or progress toward implementation of BMPs to be achieved during the permit term;''<br>
''b. the year each BMP is expected to be implemented;''<br>
''c. a target year the applicable WLA(s) will be achieved; and''<br>
''d. if the applicant has an applicable WLA for TSS or TP, a cumulative estimate of TSS and TP load reductions (in pounds) to be
achieved during the permit term and the Agency-approved method used to determine the estimate.
Agency-approved methods include "Program for Predicting Polluting Particle Passage thru Pits, Puddles, and Ponds (P8)
Urban Catchment Model", "Source Loading and Management Model for Windows (WinSLAMM)", "Minimal Impact Design
Standards (MIDS) calculator", "Minnesota Pollution Control Agency (MPCA) simple estimator tool", or any other method that
receives Agency-approval.''

[[File:Street-sweeping.jpg|300px|thumb|alt=image of street sweeper|<font size=3>Image courtesy Sarah Hobbie, University of Minnesota</font size>]]
[[File:picture of permeable interlocking concrete pavement 1.jpg|thumb|300 px|alt=Photo illustrating permeable interlocking pavement. Permeable interlocking pavers consist of concrete or stone units with open, permeable spaces between the units.|<font size=3>Photo illustrating permeable interlocking concrete pavement. <span title="Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir for temporary storage and/or infiltration. The most commonly used permeable pavement surfaces are pervious concrete, porous asphalt, and permeable interlocking concrete pavers (PICP)."> '''[https://stormwater.pca.state.mn.us/index.php?title=Permeable_pavement Permeable pavements]'''</span> are an infiltration BMP that is effective for dissolved oxygen and oxygen demand impairments.</font size>]]

The Minnesota Pollution Control Agency (MPCA) recommends including BMPs/activities in your MS4’s compliance schedule that reduce organic matter and carbon (e.g. leaf litter), since these BMPs/activities will also reduce oxygen-demanding substances in the streams (see table below). Most BMPs that reduce organic matter (e.g. street sweeping), will also reduce phosphorus, sediment and/or bacteria (''Escherichia (E.)'' coli, fecal coliform) loading to waterbodies. Additionally, if BMPs/activities are implemented across the entire jurisdictional area of your MS4, some activities may be used to demonstrate progress towards additional applicable phosphorus, total suspended solids (TSS), and/or bacteria (''E. coli'', fecal coliform) WLAs. 

{{:Potential sources of organic matter and carbon and BMPs/Activities that could be included in your compliance schedule to address dissolved oxygen/oxygen demand applicable WLAs}}

==Additional information==
Additional information on potential BMPs/activities to address the Hardwood Creek, Trott Brook Creek, and Buffalo Creek dissolved oxygen impairments may also be available in the following:

===Hardwood Creek TMDL===
*[https://www.pca.state.mn.us/sites/default/files/wq-iw8-15e.pdf TMDL Report]
*[https://www.pca.state.mn.us/sites/default/files/wq-iw8-15e.pdf TMDL Implementation Plan]
*[https://www.ricecreek.org/ Rice Creek Watershed District Comprehensive Watershed Management Plan]

===Rum River Watershed TMDL===
*[https://www.pca.state.mn.us/sites/default/files/wq-iw8-56e.pdf TMDL Report]
*[https://www.pca.state.mn.us/sites/default/files/wq-iw8-56e.pdf Watershed Restoration and Protection Strategies Report]
*[https://www.millelacsswcd.org/rum-river-one-watershed-one-plan/ Rum River One Watershed One Plan]

===South Fork Crow River Watershed TMDL===
*[https://www.pca.state.mn.us/sites/default/files/wq-iw8-52e.pdf TMDL Report]
*[https://www.pca.state.mn.us/sites/default/files/wq-ws4-47a.pdf Watershed Restoration and Protection Strategies Report]
*[http://www.crowriver.org/ CROW River Organization of Water]

==Related Pages==
Additional information and guidance related to TMDLs may be found [https://stormwater.pca.state.mn.us/index.php?title=Total_Maximum_Daily_Loads_(TMDLs) at this link].