Decew Falls Water Treatment Plant - 2023 Annual Water Quality Report

This annual water quality report summarizes the quality of drinking water from the Decew Falls Water Treatment Plant, drinking water system number 220002066, from Jan. 1 to Dec. 31, 2023.

This report satisfies the requirements of Ontario Regulation 170/03 - Drinking Water Systems.

Description of drinking water system

A conventional surface water treatment plant incorporates the following steps in its purification process:

  • Zebra mussel control
  • Travelling screens
  • Coagulation
  • Flocculation
  • Sedimentation
  • Filtration
  • Disinfection

The plant consists of three separate treatment trains; referred to as Plant 1, Plant 2, and Plant 3, with a combined rated capacity of 227,300 m3/day. Primary disinfection is achieved utilizing sodium hypochlorite with ultraviolet light as enhancement.

The Decew Falls Water Treatment Plant supplies drinking water to the City of St. Catharines (260003279), City of Thorold (260004313), Town of Niagara-on-the-Lake (260001380), and sections of the Town of Lincoln (260004306) in Niagara. The Water Treatment Plant is located at 2700 Decew Rd. in St. Catharines.

The water treatment chemicals used over this reporting period are:

  • Sodium Hypochlorite
  • Aluminum Sulphate

Monetary expenses incurred

To ensure safe and efficient operations, the following major repairs or upgrade projects took place:

Water treatment plant infrastructure

  • Plant 3 upgrade - $65,616.79
  • Intake building - $2,769,506.29
  • Valve house rehab - $19,288.61
  • High lift pump sizing - $1,453,091.79
  • Low lift booster - $1,169,373.32
  • UV upgrade - $19,163.18
  • Plant 2 upgrades - $51,220.68
  • Plant 1 mixing system - $19,477.38
  • Plant transmission main - $17,273.31
  • St. David's Road watermain (construction) - $1,753,000
  • Townline interconnect (construction) - $11,000
  • Victoria Avenue watermain (pre-construction) - $35,000
  • York Road watermain (pre-construction) - $42,500

Summary of adverse water quality incidents

The following table summarizes the notices of adverse water quality incidents submitted in accordance with the Safe Drinking Water Act. Adverse water quality incidents are reported to the Spills Action Centre and the Medical Officer of Health.

Where there have been no adverse water quality incidents for the reporting period, the table will show "NIL".

Incident date Adverse condition Corrective action Notice of issue resolution
No incident to report Not applicable Not applicable Not applicable

Water quality test results

Reported results that are shown with "ND" (non-detect) instead of a numerical value indicates that the sample result is below the lowest possible detection limit for the parameter.

Microbiological testing

Microbiological testing carried out under Schedule 10 of Ontario Regulation 170/03 - Drinking Water systems, during this reporting period.

Location Number of samples Range of E.Coli or Fecal results (minimum number) -(maximum number) Range of total Coliform results (minimum number) -(maximum number) Prescribed standard* Unit of measure
Raw 52 0 - 100 0 - 7,000 Not applicable CFU/100ml
Treated 156 0 0 Not detectable CFU/100ml
Distribution 262 0 0 Not detectable CFU/100ml

*Prescribed standards are copied from Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards.

Heterotrophic plate count testing

Heterotrophic plate count testing (HPC) is conducted on some treated and distribution system samples. The heterotrophic plate count test is used as a tool to monitor overall quality, but the results are not indicators of water safety. There is no prescribed standard for heterotrophic plate count.

Location Number of samples Range of HPC results Unit of measure
Treated 156 0 - 7 CFU/mL
Distribution 262 0 - 10 CFU/mL

Operational testing

Operational testing carried out under Schedule 7 of Ontario Regulation 170/03 - Drinking Water Systems, during this reporting period. An analyzer continuously monitors the water treatment process and records results on a predetermined frequency. Where continuous monitors are used, 8760 is reflected as the number of samples.

Parameter Number of samples Range of results (minimum number) - (maximum number) Unit of measure
Filter turbidity 8760 0.010 - 0.753 NTU*
Treated chlorine 8760 0.52 - 1.90 mg/L

*NTU (nephelometric turbidity units) is a unit that measures the lack of water clarity.

Additional testing

Summary of additional testing and sampling carried out in accordance with the requirement of an approval, order or other legal instrument.

Date of legal instrument issued Location: parameter Date sampled Result value or range (minimum number) - (maximum number) Requirement Unit of measure
Municipal Drinking Water Licence Issue 12 Aug. 13, 2021 Environmental Discharge: Free Chlorine Residual Weekly (January to December) 0 < 0.02 mg/L
Municipal Drinking Water Licence Issue 12 Aug. 13, 2021 Environmental Discharge: Total Suspended Solids Weekly (January to December) < 3 - 55 8 (annual average) mg/L
Municipal Drinking Water Licence Issue 12 Aug. 13, 2021 Raw: Microcystin Weekly (June to October) ND - 0.00015 0.0015* mg/L
Municipal Drinking Water Licence Issue 12 Aug. 13, 2021 Treated: Microcystin Weekly (June to October) ND - 0.00015 0.0015* mg/L
*Prescribed standards are copied from Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards.

Inorganic testing

Inorganic parameter testing carried out under Schedule 13 of Ontario Regulation 170/03 - Drinking Water Systems, during this reporting period. Inorganic substances include heavy metals and dissolved minerals that may be present in treated drinking water.

Parameter Number of samples Last sample date Range of results (minimum number)-(maximum number) Prescribed standard* Unit of measure Exceedance
Antimony 4 Aug. 16

ND < 0.0005

 0.006 mg/L No
Arsenic 4 Aug. 16 ND < 0.001 0.01 mg/L No
Barium 4 Aug. 16 0.019 - 0.024 1.0 mg/L No
Boron 4 Aug. 16 0.01 - 0.016 5.0 mg/L No
Cadmium 4 Aug. 16 ND 0.005 mg/L No
Chromium 4 Aug. 16 0.002 0.05 mg/L No
Fluoride 12 Nov. 6 < 0.05 - 0.09 1.5 mg/L No
Mercury 4 Aug. 16 < 0.0001 0.001 mg/L No
Nitrate 12 Aug. 16 < 0.05 - 0.41 1.0 mg/L No
Nitrite 12 Aug. 16 < 0.05 10.0 mg/L No
Selenium 4 Aug. 16 0.0007 0.05 mg/L No
Sodium 8 Aug. 16 10.7 - 14.1 20 mg/L No
Uranium 4 Aug. 16 < 0.001 0.02 mg/L No

*Prescribed standards are copied from Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards. The prescribed standard for sodium is copied from Ontario Regulation 170/03 - Drinking Water Systems.

Lead testing

Lead testing carried out under Schedule 15.1 of Ontario Regulation 170/03 - Drinking Water Systems, during this reporting period.

Location type Number of samples Last sample date Range of lead results (min to max) Prescribed standard Unit of measure Exceedance
Treated 4 Aug. 16 ND 0.010 mg/L No
Distribution 4 Aug. 16 ND 0.010 mg/L No

Organics testing

Organic parameter testing carried out under Schedule 13 of Ontario Regulation 170/03 - Drinking Water Systems, during this reporting period. Trace organic test parameters include: volatile organic substances, pesticides, solvents, dioxins, PCB's, and disinfection by-products.

Parameter Number of samples Last sample date Range of results (minimum number)-(maximum number) Prescribed standard* Unit of measure Exceedance
1,1-Dichloroethylene (vinylidene chloride) 4 Aug. 16 ND 0.014 mg/L No
1,2-Dichlorobenzene 4 Aug. 16 ND 0.2 mg/L No
1,2-Dichloroethane 4 Aug. 16 ND 0.005 mg/L No
1,4-Dichlorobenzene 4 Aug. 16 ND 0.005 mg/L No
2,3,4,6-Tetrachlorophenol 4 Aug. 16 ND 0.11 mg/L No
2,4,6-Trichlorophenol 4 Aug. 16 ND 0.005 mg/L No
2,4-Dichlorophenoxy acetic acid (2,4-D) 4 Aug. 16 ND 0.1 mg/L No
2-4 Dichlorophenol 4 Aug. 16 ND 0.9 mg/L No
2-Methyl-4-chlorophenoxyacetic acid (MCPA) 4 Aug. 16 ND 0.1 mg/L No
Alachlor 4 Aug. 16 ND 0.005 mg/L No
Atrazine + N-dealkylated metabolites 4 Aug. 16 ND 0.005 mg/L No
Azinphos-methyl 4 Aug. 16 ND 0.02 mg/L No
Benzene 4 Aug. 16 ND 0.001 mg/L No
Benzo(a)pyrene 4 Aug. 16 ND 0.00001 mg/L No
Bromoxynil 4 Aug. 16 ND 0.005 mg/L No
Carbaryl 4 Aug. 16 ND 0.09 mg/L No
Carbofuran 4 Aug. 16 ND 0.09 mg/L No
Carbon tetrachloride 4 Aug. 16 ND 0.002 mg/L No
Chlorpyrifos 4 Aug. 16 ND 0.09 mg/L No
Diazinon 4 Aug. 16 ND 0.02 mg/L No
Dicamba 4 Aug. 16 ND 0.12 mg/L No
Dichloromethane 4 Aug. 16 ND 0.05 mg/L No
Diclofop-methyl 4 Aug. 16 ND 0.009 mg/L No
Dimethoate 4 Aug. 16 ND 0.02 mg/L No
Diquat 4 Aug. 16 ND 0.07 mg/L No
Diuron 4 Aug. 16 ND 0.15 mg/L No
Glyphosate 4 Aug. 16 ND 0.28 mg/L No
HAA - Distribution (latest running annual average) 12 March 31 0.020 0.080 (running annual average) mg/L No
Malathion 4 Aug. 16 ND 0.19 mg/L No
Metolachlor 4 Aug. 16 ND 0.05 mg/L No
Metribuzin 4 Aug. 16 ND 0.08 mg/L No
Monochlorobenzene 4 Aug. 16 ND 0.08 mg/L No
Paraquat 4 Aug. 16 ND 0.01 mg/L No
Pentachlorophenol 4 Aug. 16 ND 0.06 mg/L No
Phorate 4 Aug. 16 ND 0.002 mg/L No
Picloram 4 Aug. 16 ND 0.19 mg/L No
Polychlorinated Biphenyls (PCB) 4 Aug. 16 ND 0.003 mg/L No
Prometryne 4 Aug. 16 ND 0.001 mg/L No
Simazine 4 Aug. 16 ND 0.01 mg/L No
Terbufos 4 Aug. 16 ND 0.001 mg/L No
Tetrachloroethylene 4 Aug. 16 ND 0.01 mg/L No
THM - Distribution (latest running annual average) 12 March 31 0.019

0.100 (running annual average)

 mg/L No
Triallate 4 Aug. 16 ND 0.23 mg/L No
Trichloroethylene 4 Aug. 16 ND 0.005 mg/L No
Trifluralin 4 Aug. 16 ND 0.045 mg/L No
Vinyl Chloride 4 Aug. 16 ND 0.001 mg/L No

*Prescribed standards are copied from Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards.

Parameters exceeding prescribed half-standard

Any inorganic or organic parameter(s) that exceeded half the standard prescribed in Schedule 2 of prescribed standards documented in Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards or prescribed standards documented within Ontario Regulation 170/03 - Drinking Water Systems for large municipal residential drinking water systems.

Where there have been no instances of a half-standard exceedance for the reporting period, the table will show "NIL".

Sodium - Prescribed standard is <=20

Result value or range (minimum number)-(maximum number) Date of sample
13 mg/L Feb. 15
14.1 mg/L May 17
10.7 mg/L Aug. 16
12.6 mg/L Nov. 8

*Prescribed standards are copied from Ontario Regulation 169/03 - Ontario Drinking Water Quality Standards. The prescribed standard for sodium is copied from Ontario Regulation 170/03 - Drinking Water Systems.

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