Hypoxia Task Force Scope and Methodology

The tables below describe how the Hypoxia Task Force Searches count facilities with effluent limits and monitoring requirements for nutrients, based on methodology developed for EPA Office of Wastewater Management. For a summary of the Hypoxia Task Force Searches and Logic, see the Hypoxia Task Force Searches Memorandum (PDF) (9 pp, 484K).

Permit Types

ElementHTF Counts Methodology
NPDES Individual Permits✔*
NPDES Master General Permits 
General Permit Covered Facilities 

Permit Status

ElementHTF Counts Methodology
Active Permits Only: Administratively Continued (ADC), Effective (EFF), or Expired (EXP) in the Respective Reporting Year.✔

Permit Version

ElementHTF Counts Methodology
Most Recent Permit Version Effective During the Respective Reporting Year✔

Permitted Features

ElementHTF Counts Methodology
External Outfalls (EXO)✔
Summation Outfalls (SUM)✔

Monitoring Locations

ElementHTF Counts Methodology
Net Effluent (code = 2)✔
Gross Effluent (code = 1)✔
Before/After Disinfection (codes = A & B)✔
See Comments (code = SC)✔

Units of Measure

ElementHTF Counts Methodology
Only include Mass- or Concentration-Based Units✔

Limit Value Type

ElementHTF Counts Methodology
Only include records where the Limit Value Type is populated✔

Parameter Codes

Nutrients Data Included in the Loading Tool Hypoxia Task Force (HTF) Searches
ElementHTF Counts Methodology
00600: Nitrogen, total (as N)✔
51425: Nitrogen, Total As N✔
51445: Nitrogen, Total✔
51537: Nitrogen, Net Total 
51084: Nitrogen, total available (water)✔
00602: Nitrogen, Dissolved✔
00601: Nitrogen, total 
00625: Nitrogen, Kjeldahl, total (as N)✔
51449: Nitrogen, Kjeldahl Total✔
51087: Nitrogen, Kjeldahl, total (TKN) (water)✔
82539: Nitrogen, Kjeldahl✔
49579: Nitrogen, total Kjeldahl✔
81639: Nitrogen Kjeldahl, total (TKN)✔
00623: Nitrogen, Kjeldahl, dissolved (as N)✔
0625D: Nitrogen, Kjeldahl, total [as N] [per discharge]✔
51662: Nitrogen, Kjeldahl,Total [TKN], insoluble✔
00605: Nitrogen, organic total (as N)✔
00607: Nitrogen, organic, dissolved (as N)✔
00610: Nitrogen, ammonia total (as N) 
51446: Nitrogen, Ammonia Total 
00609: Ammonia nitrogen, total, (as N) 30 day 
00612: Nitrogen, ammonia, tot unionized (as N) 
0610S: Nitrogen, ammonia total [as N] [per season] 
34726: Nitrogen, ammonia, total (as NH3) 
51085: Nitrogen, ammonia (NH3-N) 
0610D: Nitrogen, ammonia total [as N] [per discharge] 
61574: Ammonia (as N) + unionized ammonia 
00619: Ammonia, unionized 
00608: Nitrogen, ammonia dissolved 
71845: Nitrogen, ammonia total (as NH4) 
82230: Ammonia & ammonium- total 
00640: Nitrogen, inorganic total✔
51450: Nitrite Plus Nitrate Total✔
00631: Nitrite plus nitrate dissolved 1 det.✔
00630: Nitrite plus nitrate total 1 det. (as N)✔
51489: Nitrogen, Total as NO3 + NH3✔
00620: Nitrogen, nitrate total (as N)✔
82386: Nitrogen, oxidized✔
82385: Nitrogen oxides (as N) 
51448: Nitrogen, Nitrate Total✔
00618: Nitrogen, nitrate dissolved✔
00621: Nitrate nitrogen, dry weight✔
01299: Nitrogen-nitrate in water, [pct]✔
51675: Annual Nitrate Nitrogen Discharged✔
71850: Nitrogen, nitrate total (as NO3)✔
51794: Nitrite + Nitrate total [as N] 
51100: Nitrogen, total, as NO3, (water)✔
49577: Nitrite plus Nitrate, dry weight [as N] 
51086: Nitrogen, nitrate (NO3), (water)✔
00615: Nitrogen, nitrite total (as N) 
51447: Nitrogen, Nitrite Total✔
00613: Nitrite nitrogen, dissolved (as N) 
71855: Nitrogen, nitrite total (as NO2) 
00665: Phosphorus, total (as P)✔
51451: Phosphorus, Total✔
70507: Phosphorous, in total orthophosphate✔
00670: Phosphorous, total organic (as P)✔
00662: Phosphorous, total recoverable✔
00666: Phosphorus, dissolved✔
51663: Phosphorus, insoluble✔
50785: Phosphorus, ortho✔
51699: Phosphorus, Total (Avg Seasonal Load Cap)✔
0665S: Phosphorus, total [as P] [per season]✔
51426: Phosphorus, Total As P✔
51538: Phosphorus, Net Total 
00664: Dock discharge of phosphorus✔
04157: Phosphorus (reactive as P)✔
51764: Phosphorus Adsorption✔
04175: Phosphate, ortho (as P)✔
00671: Phosphate, dissolved/orthophosphate(as P)✔
70506: Phosphate, dissolved color method (as P)✔
00655: Phosphate, poly (as PO4)✔
00653: Phosphate total soluble✔
00650: Phosphate, total (as PO4)✔
00660: Phosphate, ortho (as PO4)✔
71888: Phosphorus, total soluble (as PO4)✔
70505: Phosphate, total, color method (as P)✔
51092: Phosphate, total (P2O5), water✔
51622: Limiting Nutrient (Nitrogen or Phosphorus)✔
Modeled Nutrients✔

*The HTF Methodology further excludes any permits that have a non-numeric third character (e.g., ALR000123)