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DECISION ID |
7114 |
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| Pollutant: |
Ammonia |
| Final Listing Decision: |
Delist from 303(d) list (TMDL required list) |
| Last Listing Cycle's Final Listing Decision: |
List on 303(d) list (TMDL required list)(2006) |
| Revision Status |
Revised |
| Reason for Delisting: |
State determines water quality standard is being met |
| Impairment from Pollutant or Pollution: |
Pollutant |
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| Weight of Evidence: |
This pollutant is being considered for removal from the section 303(d) list under section 4.1 of the Listing Policy. Under this section a single line of evidence is necessary to assess listing status.
Two line of evidence is available in the administrative record to assess this pollutant.
Line of evidence (LOE) 4278 will not be considered for this decision because it is a placeholder LOE. The original data was not able to be assessed using current standards due to lack of temperature and pH data. The recent data listed in LOE 27904 provides a sufficient assessment of conditions in the water body.
Based on the readily available data and information, the weight of evidence indicates that there is sufficient justification for removing this water segment-pollutant combination from the section 303(d) list.
This conclusion is based on the staff findings that:
1. The data used satisfies the data quality requirements of section 6.1.4 of the Policy.
2. The data used satisfies the data quantity requirements of section 6.1.5 of the Policy.
3. One of 29 samples exceeded the the 30-day average objective for ammonia and this does not exceed the allowable frequency listed in Table 4.1 of the Listing Policy.
4. Pursuant to section 4.11 of the Listing Policy, no additional data and information are available indicating that standards are not met. |
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| RWQCB Board Decision / Staff Recommendation: |
After review of the available data and information, RWQCB staff concludes that the water body-pollutant combination should be removed from the section 303(d) list because applicable water quality standards for the pollutant are not being exceeded. |
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| SWRCB Board Decision / Staff Recommendation: |
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| USEPA Decision: |
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| LOE ID: |
27904 |
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| Pollutant: |
Ammonia |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
None |
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| Beneficial Use: |
Warm Freshwater Habitat |
| Aquatic Life Use: |
Preservation of Rare & Endangered Species | Wetland Habitat | Wildlife Habitat |
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| Number of Samples: |
29 |
| Number of Exceedances: |
1 |
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| Data and Information Type: |
Fixed station physical/chemical (conventional plus toxic pollutants) |
| Data Used to Assess Water Quality: |
One of 29 samples exceeded the 30-day average objective for ammonia. Water quality samples were taken and analyzed for ammonia in as part of the City of Los Angeles Watershed Protection Division's Machado Lake Nutrients Monitoring Program. |
| Data Reference: |
Water quality monitoring for Wilmington Drain at Lomita Blvd. |
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| Water Quality Objective/Criterion: |
The Basin Plan states, "In order to protect aquatic life, ammonia concentrations in inland surface waters characteristic of freshwater shall not exceed the values calculated for the appropriate instream conditions shown in Tables 3-1 3-3." The one-hour average objective is dependent on pH and the presence or absence of early life stages of fish (ELS) but not temperature. The 30-day average objective is dependent on pH, temperature and ELS in Tables 3-1 to 3-3. The ammonia objectives and the pH and temperature dependent formula are found in Attachment A of Regional Board Resolution No. 2002-011. |
| Objective/Criterion Reference: |
Water Quality Control Plan Los Angeles Region R4 Basin Plan |
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Basin Plan Amendments to the Water Quality Control Plan Los Angeles Region R4 Basin Plan as of 02/02/2009 |
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| Evaluation Guideline: |
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| Guideline Reference: |
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| Spatial Representation: |
The City of Los Angeles Watershed Protection Division conducted sampling in Wilmington Drain at the water quality monitoring station near Lomita Boulevard. |
| Temporal Representation: |
Grab samples were taken and analyzed on a biweekly basis from October 2007 to June 2008. |
| Environmental Conditions: |
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| QAPP Information: |
Data was collected in accordance with the City of Los Angeles Pollution Assessment Section's Standard Operating Procedures for monitoring and testing. |
| QAPP Information Reference(s): |
Electronic correspondence between Regional Board staff and City of Los Angeles Watershed Protection Division. |
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| LOE ID: |
4278 |
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| Pollutant: |
Ammonia |
| LOE Subgroup: |
Pollutant-Water |
| Matrix: |
Water |
| Fraction: |
Not Recorded |
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| Beneficial Use: |
Warm Freshwater Habitat |
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| Number of Samples: |
0 |
| Number of Exceedances: |
0 |
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| Data and Information Type: |
Not Specified |
| Data Used to Assess Water Quality: |
Unspecified--This LOE is a placeholder to support a 303(d) listing decision made prior to 2006. |
| Data Reference: |
Placeholder reference pre-2006 303(d) |
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| Water Quality Objective/Criterion: |
Unspecified |
| Objective/Criterion Reference: |
Placeholder reference pre-2006 303(d) |
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| Evaluation Guideline: |
Unspecified |
| Guideline Reference: |
Placeholder reference pre-2006 303(d) |
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| Spatial Representation: |
Unspecified |
| Temporal Representation: |
Unspecified |
| Environmental Conditions: |
Unspecified |
| QAPP Information: |
Unspecified |
| QAPP Information Reference(s): |