Hypoxia Task Force Scope and Methodology

The table below describes 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).

Nutrients Data Included in the Loading Tool Hypoxia Task Force (HTF) Searches
ElementHTF Counts Methodology
Permit Types
NPDES Individual Permits✔*
NPDES Master General Permits 
General Permit Covered Facilities 
Permit Status
Active Permits Only: Administratively Continued (ADC), Effective (EFF), or Expired (EXP) in the Respective Reporting Year.
Permit Version
Most Recent Permit Version Effective During the Respective Reporting Year
Permitted Features
External Outfalls (EXO)
Summation Outfalls (SUM)
Monitoring Locations
Net Effluent (code = 2)
Gross Effluent (code = 1)
Before/After Disinfection (codes = A & B)
See Comments (code = SC)
Units of Measure
Only include Mass- or Concentration-Based Units
Limit Value Type
Only include records where the Limit Value Type is populated
Parameter Codes
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)

Top of Page