San Mateo, City of

NPDES permit CA0037541 · Major POTW · effective, expires 2028-11-30 · EPA's file as of 2026-09-19

Check this month's numbers before you file

EPA's record, 2025-09-01 to 2026-08-31

0values over a limit
0required values missing, on 0 form(s)
0of 42 forms filed late

Last period with anything received: 2026-07-31.

Reporting

Reports are due about 32 days after each monitoring period ends (the most common figure among CA permits in EPA's filings — check your permit).

Limits in force (61)

OutfallParameterStatisticLimitMonths
EFF1pHINST MIN >= 6 SU all year
EFF1pHINST MAX <= 9 SU all year
EFF1Solids, total suspendedMO AVG <= 20 mg/L May, Jun, Jul, Aug, Sep
EFF1Solids, total suspendedMO AVG <= 30 mg/L Jan, Feb, Mar, Apr, Oct, Nov, Dec
EFF1Solids, total suspendedWKLY AVG <= 30 mg/L May, Jun, Jul, Aug, Sep
EFF1Solids, total suspendedWKLY AVG <= 45 mg/L Jan, Feb, Mar, Apr, Oct, Nov, Dec
EFF1Nitrogen, ammonia total [as N]MO AVG report only all year
EFF1Nitrogen, ammonia total [as N]DAILY MX report only all year
EFF1Nitrogen, ammonia total [as N]MO AVG report only all year
EFF1Nitrogen, ammonia total [as N]DAILY MX report only all year
EFF1Nitrite + Nitrate total [as N]MO AVG report only all year
EFF1Nitrite + Nitrate total [as N]DAILY MX report only all year
EFF1Nitrite + Nitrate total [as N]MO AVG report only all year
EFF1Nitrite + Nitrate total [as N]DAILY MX report only all year
EFF1Nitrogen, inorganic totalMO AVG report only all year
EFF1Nitrogen, inorganic totalDAILY MX report only all year
EFF1Nitrogen, inorganic totalMO AVG report only all year
EFF1Nitrogen, inorganic totalDAILY MX report only all year
EFF1Phosphorus, total [as P]MO AVG report only all year
EFF1Phosphorus, total [as P]DAILY MX report only all year
EFF1Phosphorus, total [as P]MO AVG report only all year
EFF1Phosphorus, total [as P]DAILY MX report only all year
EFF1Cyanide, total [as CN]MO AVG <= 19 ug/L all year
EFF1Cyanide, total [as CN]DAILY MX <= 38 ug/L all year
EFF1Nickel, total [as Ni]MO AVG <= 30 ug/L all year
EFF1Nickel, total [as Ni]DAILY MX <= 71 ug/L all year
EFF1Copper, total recoverableMO AVG <= 51 ug/L all year
EFF1Copper, total recoverableDAILY MX <= 72 ug/L all year
EFF1DioxinMO AVG <= .000014 ng/L all year
EFF1DioxinDAILY MX <= .000028 ng/L all year
EFF1Chlorine, total residual1I <= .34 mg/L all year
EFF1Nitrogen, Ammonia TotalMO AVG <= 66 mg/L all year
EFF1Nitrogen, Ammonia TotalDAILY MX <= 120 mg/L all year
EFF1Polychlorinated biphenyls [PCBs], sum of congenersMO AVG report only all year
EFF1Polychlorinated biphenyls [PCBs], sum of congenersDAILY MX report only all year
EFF1Polychlorinated biphenyls [PCBs], sum of AroclorsMO AVG report only all year
EFF1Polychlorinated biphenyls [PCBs], sum of AroclorsDAILY MX report only all year
EFF1Mercury, total recoverableMO AVG report only all year
EFF1Mercury, total recoverableWKLY AVG report only all year
EFF1FlowDAILY AV report only all year
EFF1FlowMO TOTAL report only all year
EFF1BOD, carbonaceous [5 day, 20 C]MO AVG <= 15 mg/L May, Jun, Jul, Aug, Sep
EFF1BOD, carbonaceous [5 day, 20 C]MO AVG <= 25 mg/L Jan, Feb, Mar, Apr, Oct, Nov, Dec
EFF1BOD, carbonaceous [5 day, 20 C]WKLY AVG <= 25 mg/L May, Jun, Jul, Aug, Sep
EFF1BOD, carbonaceous [5 day, 20 C]WKLY AVG <= 40 mg/L Jan, Feb, Mar, Apr, Oct, Nov, Dec
EFF1BOD, carb-5 day, 20 deg C, percent removalMO AV MN >= 85 % all year
EFF1Solids, suspended percent removalMO AV MN >= 85 % all year
EFF1Pass/Fail Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia)VALUE <= 1 pass=0;fail=1 all year
EFF1Chronic Mthd, Survival Endpt %Effect, Growth Endpt Median TSTcHo R/nR Pass/Fail, StatR7d A bahiaVALUE <= 1 pass=0;fail=1 all year
EFF1Chronic Mthd, Survival Endpt %Effect, Growth Endpt Median TSTcHo R/nR Pass/Fail, StatR7d A bahiaTOTAL < 50 % effect all year
EFFDEnterococciGEO MEAN <= 270 CFU/100mL all year
EFFDEnterococci9C <= 1100 CFU/100mL all year
INF1Solids, total suspendedDAILY MX report only all year
INF1Cyanide, total [as CN]DAILY MX report only all year
INF1FlowDAILY AV report only all year
INF1FlowMO TOTAL report only all year
INF1BOD, carbonaceous [5 day, 20 C]DAILY MX report only all year
SUMMercury, total recoverableANNL AVG report only all year
SUR1Pass/Fail Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia)VALUE report only all year
SUR1Chronic Mthd, Survival Endpt %Effect, Growth Endpt Median TSTcHo R/nR Pass/Fail, StatR7d A bahiaVALUE report only all year
SUR1Chronic Mthd, Survival Endpt %Effect, Growth Endpt Median TSTcHo R/nR Pass/Fail, StatR7d A bahiaTOTAL report only all year

Built from EPA's ECHO bulk files. EPA's file, not the permit document, is the source: read your permit. Check a report before you file it · All states