2008 MSGP Benchmark Discharge Monitoring Report Analysis and SWPPP 

Compliance Review

Summary: EPA conducted an analysis of benchmark monitoring data that was available in the eNOI 

system and performed a compliance review of a random sample of SWPPPs and DMR data. 

Benchmark Monitoring

About half (1,200) of the covered facilities in the MSGP are required to perform benchmark monitoring 

in 4 consecutive quarters. The facilities are required to submit monitoring results to EPA either 

electronically or through paper format. Many facilities submitted their results through paper format 

and these results were not accessible via the database. There were 485 facilities that did submit their 

monitoring results electronically and EPA’s analysis focused on these facilities. Note that the revised 

MSGP proposes to require facilities to submit their results electronically unless they receive a waiver 

from the regional office. There were 42,351 monitoring records from the 485 facilities, but many of 

these records were unusable because of various reasons. For instance, there was missing information

(e.g., parameter name was not provided, monitoring data was not associated with the benchmark 

monitoring program, facilities terminated coverage, hardness data was missing for the 6 hardnessdependent metals). In addition many records were not analyzed because the records were not reported 

within the standard reporting quarters given in the permit. Yearly averages were computed only when 

there were records from each of the 4 standard quarterly reporting periods. This left 183 facilities with 

1,334 annual benchmark averages that could be analyzed. Note that a given facility/outfall could have 

1-3 yearly averages for a given parameter. The resulting data were sorted then analyzed by permit, 

outfall and parameter.

This analysis shows that compliance with the monitoring requirements is a significant issue and that 

mistakes are common. The new eNOI system will provide the appropriate monitoring requirements to 

permittees automatically and will also make the data accessible to Regions for better programmatic 

oversight. A summary of the monitoring results is provided in Attachment A. 

Analysis of SWPPPs

EPA sent a request for information pursuant to Section 308 of the Clean Water Act to 25 industrial 

facilities requesting a copy of their current stormwater pollution prevention plan (SWPPP). The letter 

specifically asked for information on corrective actions and benchmark exceedances. Twenty SWPPPs 

were received and reviewed. Each SWPPP review looked at general completeness, ESA eligibility 

criteria, monitoring results for both benchmark monitoring and effluent limitation monitoring (if 

applicable) and corrective actions/SWPPP modifications taken. The review did not assess whether the 

SWPPP complied with all the detailed requirements of Part 5 of the 2008 MSGP. The review, instead,

focused on monitoring data and the corrective actions the facility took when problems were identified.

EPA found that most facilities (89%) are developing complete SWPPPs, but there is significant 

noncompliance with monitoring requirements. Only 35% of facilities submitted complete monitoring 

data and all facilities that submitted benchmark monitoring data had at least one benchmark 
exceedance. Of the facilities that completed benchmark monitoring, 84% identified corrective actions.

None of the facilities reviewed had documented a clear reduction in benchmark exceedances after 

implementing corrective actions; most facilities continued to have benchmark exceedances after the 

corrective actions. A summary of the SWPPP and DMR compliance results from the 20 facilities 

reviewed is provided in Attachment B.
Attachment A

Benchmark Monitoring Screening / Analysis - Results Summary

Table 1. Overall comparison of quarterly benchmark DMR data to benchmark monitoring values

Simplified Pollutant Name Number 

of 

Permitees

Number of 

Permitees 

with 1 or 

More Yearly 

Average 

Exceeding 

Benchmark

Number 

of 

Outfalls

Number of 

Outfalls 

with 1 or 

More Yearly 

Average 

Exceeding 

Benchmark

Number of 

Annual 

Averages

(4 samples)

Number of 

Annual 

Averages 

Exceeding 

Benchmark

Aluminum 66 39 127 58 178 67

Ammonia 1 0 1 0 1 0

Arsenic 1 0 1 0 1 0

Biochemical Oxygen Demand (BOD5) 3 2 10 3 10 3

Cadmium* 1 0 1 0 1 0

Chemical Oxygen Demand (COD) 40 23 82 29 107 39

Copper* 42 34 81 64 121 93

Cyanide 1 0 1 0 1 0

Iron 114 90 205 152 312 221

Lead* 39 16 62 25 84 29

Magnesium 1 1 1 1 1 1

Mercury 2 0 2 0 2 0

Nitrate + Nitrite 33 13 58 16 71 19

pH 7 5 7 5 11 6

Phosphorus 2 0 2 0 2 0

Selenium 1 0 1 0 1 0

Silver* 1 0 1 0 1 0

Total Suspended Solids 117 43 191 60 260 67

Zinc* 60 43 118 72 169 107

*Parameters that have hardness-specific benchmark monitoring requirements.

Aluminum. There were 66 facilities (127 outfalls) that reported sufficient data to compute yearly 

averages. Of those facilities (outfalls) with yearly averages, 39 (58) had one or more yearly averages 

exceeding the benchmark value. Of all the 178 yearly averages, 67 (38%) exceeded their corresponding 

benchmark value.

Ammonia. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average did not exceed the benchmark value. 

Arsenic. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average did not exceed the benchmark value. 

Biochemical Oxygen Demand (BOD5). There were 3 facilities (10 outfalls) that reported sufficient data 

to compute yearly averages. Of those facilities (outfalls) with yearly averages, 2 (3) had one or more 

yearly averages exceeding the benchmark value. Of all the 10 yearly averages, 3 (30%) exceeded their 

corresponding benchmark value.

Cadmium. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average did not exceed the benchmark value. 
Chemical Oxygen Demand (COD). There were 40 facilities (82 outfalls) that reported sufficient data to 

compute yearly averages. Of those facilities (outfalls) with yearly averages, 23 (29) had one or more 

yearly averages exceeding the benchmark value. Of all the 107 yearly averages, 39 (36%) exceeded their 

corresponding benchmark value.

Copper. There were 42 facilities (81 outfalls) that reported sufficient data to compute yearly averages. 

Of those facilities (outfalls) with yearly averages, 34 (64) had one or more yearly averages exceeding the 

benchmark value. Of all the 121 yearly averages, 93 (77%) exceeded their corresponding benchmark 

value.

Cyanide. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average did not exceed the benchmark value. 

Iron. There were 114 facilities (205 outfalls) that reported sufficient data to compute yearly averages. Of 

those facilities (outfalls) with yearly averages, 90 (152) had one or more yearly averages exceeding the 

benchmark value. Of all the 312 yearly averages, 221 (71%) exceeded their corresponding benchmark 

value.

Lead. There were 39 facilities (62 outfalls) that reported sufficient data to compute yearly averages. Of 

those facilities (outfalls) with yearly averages, 16 (25) had one or more yearly averages exceeding the 

benchmark value. Of all the 84 yearly averages, 29 (35%) exceeded their corresponding benchmark 

value.

Magnesium. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average exceeded the benchmark value. 

Mercury. There were 2 facilities (2 outfalls) that reported sufficient data to compute yearly averages. Of 

those facilities (outfalls) with yearly averages, 0 (0) had one or more yearly averages exceeding the 

benchmark value. Of all the 2 yearly averages, 0 (0%) exceeded their corresponding benchmark value.

Nitrate + Nitrite. There were 33 facilities (58 outfalls) that reported sufficient data to compute yearly 

averages. Of those facilities (outfalls) with yearly averages, 13 (16) had one or more yearly averages 

exceeding the benchmark value. Of all the 71 yearly averages, 19 (27%) exceeded their corresponding 

benchmark value.

pH. There were 7 facilities (7 outfalls) that reported sufficient data to compute yearly averages. Of those 

facilities (outfalls) with yearly averages, 5 (5) had one or more yearly averages exceeding the benchmark 

value. Of all the 11 yearly averages, 6 (55%) exceeded their corresponding benchmark value.

Phosphorus. There were 2 facilities (2 outfalls) that reported sufficient data to compute yearly averages. 

Of those facilities (outfalls) with yearly averages, 0 (0) had one or more yearly averages exceeding the 

benchmark value. Of all the 2 yearly averages, 0 (0%) exceeded their corresponding benchmark value.

Selenium. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its 

yearly average did not exceed the benchmark value. 

Silver. There was 1 facility (1 outfall) that reported sufficient data to compute yearly averages. Its yearly 

average did not exceed the benchmark value. 

Total Suspended Solids. There were 117 facilities (191 outfalls) that reported sufficient data to compute 

yearly averages. Of those facilities (outfalls) with yearly averages, 43 (60) had one or more yearly 
averages exceeding the benchmark value. Of all the 260 yearly averages, 67 (26%) exceeded their 

corresponding benchmark value.

Zinc. There were 60 facilities (118 outfalls) that reported sufficient data to compute yearly averages. Of 

those facilities (outfalls) with yearly averages, 43 (72) had one or more yearly averages exceeding the 

benchmark value. Of all the 169 yearly averages, 107 (63%) exceeded their corresponding benchmark 

value.

Table 2. Sector-specific comparison of quarterly benchmark monitoring data to benchmark monitoring 

values.

Sector Simplified Pollutant Name Number of 

Permitees

Number of 

Permitees 

with 1 or 

More 

Yearly 

Average 

Exceeding 

Benchmark

Number 

of 

Outfalls

Number of 

Outfalls 

with 1 or 

More Yearly 

Average 

Exceeding 

Benchmark

Number 

of 

Annual 

Averages 

(4 

samples)

Number of 

Annual 

Averages 

Exceeding 

Benchmark

A Chemical Oxygen Demand (COD) 8 4 21 6 24 8

A Copper 1 1 1 1 2 2

A Total Suspended Solids 8 3 20 4 25 4

A Zinc 4 2 11 2 12 2

B Chemical Oxygen Demand (COD) 3 0 7 0 11 0

C Aluminum 4 3 15 4 26 5

C Iron 5 5 16 8 27 13

C Lead 1 0 1 0 1 0

C Nitrate + Nitrite 5 3 16 3 18 3

C Phosphorus 2 0 2 0 2 0

C Zinc 2 2 2 2 2 2

D Total Suspended Solids 14 3 18 4 28 4

E Iron 15 9 17 11 21 15

E Total Suspended Solids 18 4 20 4 26 5

F Aluminum 7 3 17 4 24 5

F Copper 8 5 19 12 38 27

F Iron 4 3 10 5 16 8

F Total Suspended Solids 4 9 0 12 0

F Zinc 11 8 27 17 50 36

J Nitrate + Nitrite 9 2 13 2 16 4

J Total Suspended Solids 25 4 32 4 48 4

K Ammonia 1 0 1 0 1 0

K Arsenic 1 0 1 0 1 0

K Cadmium 1 0 1 0 1 0

K Chemical Oxygen Demand (COD) 1 0 1 0 1 0

K Cyanide 1 0 1 0 1 0

K Lead 1 0 1 0 1 0

K Magnesium 1 1 1 1 1 1

K Mercury 1 0 1 0 1 0

K Selenium 1 0 1 0 1 0

K Silver 1 0 1 0 1 0

L Iron 5 5 17 16 22 20

L Total Suspended Solids 11 6 28 13 40 15

M Aluminum 10 3 15 4 24 6

M Iron 10 5 15 8 25 13

M Lead 10 2 15 4 23 5

M Total Suspended Solids 10 1 15 2 23 2

N Aluminum 23 18 41 27 57 30
Sector Simplified Pollutant Name Number of 

Permitees

Number of 

Permitees 

with 1 or 

More 

Yearly 

Average 

Exceeding 

Benchmark

Number 

of 

Outfalls

Number of 

Outfalls 

with 1 or 

More Yearly 

Average 

Exceeding 

Benchmark

Number 

of 

Annual 

Averages 

(4 

samples)

Number of 

Annual 

Averages 

Exceeding 

Benchmark

N Chemical Oxygen Demand (COD) 23 16 41 19 56 24

N Copper 19 16 36 30 51 38

N Iron 23 22 41 38 58 51

N Lead 19 14 36 22 50 25

N Total Suspended Solids 23 14 41 19 54 20

N Zinc 19 17 36 28 52 35

O Iron 16 13 35 28 63 42

Q Aluminum 3 2 3 2 5 2

Q Iron 4 2 4 2 6 2

Q Lead 1 1 0 3 0

Q Zinc 2 2 2 2 4 4

U Biochemical Oxygen Demand 

(BOD5)

1 0 5 0 5 0

U Chemical Oxygen Demand (COD) 1 0 5 0 5 0

U Nitrate + Nitrite 1 1 5 1 5 1

U Total Suspended Solids 1 1 5 1 5 1

Y Zinc 1 0 1 0 1 0

AA Aluminum 8 5 17 7 22 8

AA Iron 9 7 19 12 26 17

AA Nitrate + Nitrite 9 4 13 5 19 5

AA Zinc 9 7 18 13 27 20
Attachment B

Compliance Review of a Random Sample of SWPPPs and DMR Data –

Results Summary

Activity Result Notes

Used the EPA SWPPP template 7 of 20 facilities (35%)

Submitted a complete and detailed 

SWPPP

17 of 19 facilities (89%) 

submitted a complete and 

detailed SWPPP

All facilities that used the EPA 

SWPPP template had a 

complete and detailed SWPPP; 

1 facility did not submit SWPPP

Submitted complete monitoring 

data

7 of 20 facilities (35%) 

submitted complete 

monitoring data

4 facilities did not submit data, 

while others did not submit 

data for all pollutants

Exceeded benchmark requirements 16 of 16 facilities (100%) 

exceeded at least 1 benchmark 

value

4 facilities did not submit 

monitoring data, or did not 

provide data in a usable 

format.

Exceeded effluent limits 1 of 3 facilities (33%) 2 facilities did not exceeded 

ELG requirements, while 4 

facilities did not provide ELG 

data

Identified corrective actions 16 of 19 facilities (84%) 1 facility did not submit any 

annual reports

Submitted annual reports 19 of 20 facilities (95%)