m |
m |
||
Line 1: | Line 1: | ||
{{alert|This page is under review during the MS4 Phase 2 permit reissuance period|alert-under-review}} | {{alert|This page is under review during the MS4 Phase 2 permit reissuance period|alert-under-review}} | ||
+ | |||
+ | [[File:General information page image.png|right|100px|alt=image]] | ||
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). | 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). |
The amount of dissolved oxygen (DO) an aquatic organism needs depends upon species, water temperature, and other factors such as the life stage of an organism. For most 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).
Waters that have adequate DO under natural conditions but that are impaired for DO typically have one or more anthropogenic 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 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 water quality standards, which range from 1.5 to 3.5 depending on geographic location.
Currently there are three approved total maximum daily load (TMDLs) for Hardwood Creek (Waterbody ID: 07010206-596), Trott Brook (Waterbody ID: 07010207-680), and Buffalo Creek (Waterbody ID: 07010205-638 (formerly 07010205-501)) that include MS4 (Municipal Separate Storm Sewer System) wasteload allocations (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.
A compliance schedule is a a schedule of compliance leading to compliance with Clean Water Act regulations. Compliance schedules must meet the following.
|
A compliance schedule is required at the time of application if the permittee has an applicable WLA for dissolved oxygen/oxygen demand (biochemical oxygen demand (BOD), total oxygen demand (TOD), and/or nitrogenous biochemical oxygen demand (NBOD) that includes a reduction greater than zero percent.
In the compliance schedule, the permittee must provide the following information:
MS4s with applicable dissolved oxygen/oxygen demand WLAs
Link to this table
TMDL Project | MS4 with a WLA for oxygen demand |
---|---|
Hardwood Creek Impaired Biota and Dissolved Oxygen TMDL | Anoka County |
Hugo City | |
Lino Lakes City | |
MNDOT Metro District | |
Rice Creek Watershed District | |
Washington County | |
Trott Brook (Rum River Watershed TMDL) | Elk River City |
Nowthen City | |
Ramsey City | |
Saint Francis City | |
Sherburne County | |
Buffalo Creek (South Fork Crow River Watershed TMDL) | Glencoe City |
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
Link to this table
General Category | Source | BMP/Activity |
---|---|---|
MS4 Infrastructure | Decaying plant matter, litter, and sediment in the storm drain system | Enhance street sweeping program |
Remove leaf litter and soil in street and gutters (e.g. implement an Adopt-a-storm drain program). Educate property owners on proper yard waste management | ||
Stormwater runoff from impervious surfaces | Implement source, rate, volume controls (i.e. adopt minimal impact design standards (MIDS) for new, redevelopment, and linear projects) | |
Minimize impervious surfaces | ||
Implement filtration practices, infiltration practices, and sedimentation practices | ||
Domestic pets | Dogs, cats, dog parks, walking trails, residential yard and sidewalk runoff (spring runoff after winter accumulation) | Install pet waste disposal stations along trails, in dog parks, etc |
Pass and enforce pet waste ordinances and educate pet owners about them | ||
Add infiltration BMPs downstream of parks/residential areas and upstream of stormwater pipes (i.e., somewhere between the park/residential area and the stormwater outfall to intercept and infiltrate some or all of the flow from these areas) | ||
Residential sources | See this section | |
Industrial and commercial practices | See this section |
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:
Total Maximum Daily Loads (TMDLs) are EPA approved amounts of pollutant loading that can occur and have a water body meet water quality standards. This page is collection of links and resources to better understand, and meet, TMDL requirements.