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H. Public Hearing - MS4 Sampling Plan_W10ft1** CITY OF City of Kalispell ALISPELL post Office Box 1997 -Kalispell, Montana 59903 Telephone: (406) 758-7701 Fax: (406) 758-7758 MEMORANDUM To: Doug Russell, City Manager From: Susie Turner, P.E., Public Works Director Meeting Date: February 3, 2020 Re: Public Hearing for the "MS4 Sampling Plan for TMDL-Related Monitoring" BACKGROUND: The City of Kalispell (City) operates its storm drainage system under the authorization of the Montana Pollution Discharge Elimination System (MPDES) General Permit for Storm Water Discharges Associated with Small Municipal Separate Storm Sewer Systems (MS4s), hereafter referred to as the MS4 General Permit. The current MS4 General Permit, issued by the Montana Department of Environmental Quality (DEQ), is effective from January 1, 2017 through December 31, 2021. In accordance with Part III of the MS4 General Permit, the City is required to develop a sampling plan for total maximum daily load (TMDL) related monitoring, due with the first year's annual report. Similarly, Part IV of the MS4 General Permit requires semi-annual monitoring (self -monitoring) that may be satisfied entirely or in part by the TMDL-related monitoring required under Part III. The MS4 General Permit required the sampling be submitted to DEQ for approval with the first annual report. Further, after the sampling plan is approved by DEQ, the Permittee must provide a mechanism for public review. In 2017, the City, in conjunction with HDR, developed the "MS4 Sampling Plan for TMDL- Related Monitoring" to comply with the MS4 General Permit requirements. The plan was submitted to DEQ for review with the City's 2017 MS4 Annual Report. On December 31, 2019, the City received notification of approval from DEQ on Kalispell's Sampling Plan and DEQ requested the City make the plan available to the public for review. Self -monitoring data is compiled and evaluated each year in a report and sent to DEQ with the required Annual Report. The 2019 monitoring results are attached. TMDL monitoring data will be included with the 4t' Annual Report in a requited TMDL section. As part of the consideration for the "MS4 Sampling Plan for TMDL-Related Monitoring", a public hearing was set to encourage public interaction and receive comments. The Plan was advertised via local newspaper, social media, and on the City website. Thus far, the City has not received any comments. ATTACHMENTS: MS4 Sampling Plan for TMDL-Related Monitoring 2019 Monitoring Results A?UNTAN: 1 Ih Prepared by MS4 Sampling Plan for TMDL-Related Monitoring City of Kalispell, Montana Storm Water Management Program January 9, 2018 This page intentionally left blank City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring Table of Contents 1 Introduction.....................................................................................................................................1 1.1. Background.............................................................................................................................1 1.2. Purpose...................................................................................................................................1 2 Kalispell MS4-Related TMDLs.......................................................................................................1 2.1. TMDL Overview......................................................................................................................1 2.2. TMDL Strategy........................................................................................................................2 3 Monitoring Locations and Strategies..............................................................................................2 3.1. Sites 001 and 001 a: Hydrodynamic Separator Effectiveness Evaluation ..............................2 3.2. Site 002: Assess Future BMP Performance in Commercial/ Industrial Area.........................3 3.3. Site 004: Assess Future BMP Performance in Residential Area...........................................4 4 Monitoring Requirements...............................................................................................................6 4.1. Field Sampling Methods.........................................................................................................6 4.2. Sampling Parameters and Analytical Methods......................................................................7 4.3. Sample Handling and Documentation....................................................................................7 4.4. Storm Events and Sample Frequency....................................................................................8 4.5. Quality Assurance/Quality Control..........................................................................................9 4.6. Analysis of Results................................................................................................................9 5 Reporting........................................................................................................................................9 Figure 1. Monitoring Sites 001 and 001a Figure 2. Monitoring Site 002.................. Figure 3. Monitoring Site 004.................. Figures Tables Table 1. Summary of TMDLs with Kalispell MS4 Approved WLAs Table 2. TMDL-Related Monitoring Sample Locations ................... Table 3. Self -Monitoring Sample Locations .................................... Table 4. Analytical Methods............................................................ Appendices Appendix A —Supplemental Figures 3 4 5 2 5 6 8 January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring 1 Introduction BaCKground The City of Kalispell (City) operates its storm drainage system under the authorization of the Montana Pollution Discharge Elimination System (MPDES) General Permit for Storm Water Discharges Associated with Small Municipal Separate Storm Sewer Systems (MS4s), hereafter referred to as the MS4 General Permit. The current MS4 General Permit, issued by the Montana Department of Environmental Quality (MDEQ), is effective from January 1, 2017 through December 31, 2021. In accordance with Part III of the MS4 General Permit, the City is required to develop a sampling plan for total maximum daily load (TMDL) related monitoring, due with the first year's annual report; and a TMDL section in its Storm Water Management Program (SWMP), due with the fourth year's annual report. The results from the TMDL-related monitoring will be used in conjunction with the TMDL section of the SWMP to address applicable TMDLs. Similarly, Part IV of the MS4 General Permit requires semi-annual monitoring (self -monitoring) that may be satisfied entirely or in part by the TMDL-related monitoring required under Part III. 1.2. Purpose The purpose of this sampling plan is to describe the City's TMDL-related monitoring program for the 2017 through 2021 permit term. More specific details relating to the purpose of this plan are as follows: ■ The City has selected TMDL-related monitoring Option 2; therefore, this plan will be implemented to track and evaluate effectiveness of BMPs selected for reducing MS4 loading to impaired waterbodies. ■ In accordance with the MS4 General Permit requirements, this plan will ultimately become a part of the TMDL section of the City's SWMP (which will be submitted with the fourth year's annual report in 2020). ■ The City has selected self -monitoring Option 2 (see Part IV of the MS4 General Permit). The monitoring locations identified in this plan will also be used to fulfill the self -monitoring requirements. Additional discussion on the City's plan for self -monitoring is provided in Section 8 of the City's SWMP. ■ This document, when implemented, will fulfill the requirements of Part 111.13 of the MS4 General Permit, requiring a sampling plan for TMDL-Related Monitoring. 2 Kalispell MS4-Related TMDLs M . TMDL Overview There are six named or perennial surface waters that receive stormwater discharges from the City's MS4 outfalls. These receiving waters are as follows: ■ Whitefish River ■ Stillwater River ■ Ashley Creek January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring Spring Creek Bowser/Little Spring Creek- Aka Kids Creek -Classified as an unnamed perennial Unnamed perennial surface water tributary to Ashley Creek from Foys Lake The Whitefish River, Stillwater River, Spring Creek, and Ashley Creek are classified as impaired surface waters of the state and each has an approved pollutant TMDL with waste load allocation (WLA). Table 1 summarizes the impaired waterbodies with TMDLs within the Kalispell MS4 boundary and the associated pollutant of impairment. Figure A.1 (Appendix A) provides a map of the City's outfalls and associated receiving waterbodies. Table 1. Summary of TMDLs with Kalispell MS4 Approved WLAs Waterbody Whitefish River X Stillwater River X _ Spring Creek X X X Ashley Creek' X X X X TN is a surrogate TMDL for Nitrate+Nitrite ' Middle and Lower Segments 2.2. TMDL Strategy Part III.B of the MS4 General Permit specifies that the City shall develop and implement a section of their SWMP to address TMDLs. More specifically, the City must include in its SWMP a section identifying the measures and BMPs it plans to implement, describing the City's impairment priorities and long term strategy, and outlining interim milestones (i.e., a completion schedule for action items) for controlling the discharge of the pollutants of concern and making progress towards meeting the TMDL. The City has yet to develop this section of the SWMP; however, the City has selected its monitoring locations in watersheds where they are currently planning to implement BMPs aimed at reducing pollutants of impairment for its receiving waterbodies. Additional discussion of target pollutants and impairment priorities will be provided within the TMDL section of the SWMP when it is submitted. 3 Monitoring Locations and Strategies 3.1. Sites 001 and 001 a: Hydrodynamic Separator Effectiveness Evaluation The City installed a Downstream Defender® hydrodynamic separator in August 2016 near the intersection of Sylvan Drive and Sylvan Court (see Figure 1). This area drains to the Stillwater River, which has an MS4 WLA for sediment. The City will conduct monitoring immediately upstream and downstream of the hydrodynamic separator in order to evaluate its effectiveness at removing sediment from MS4 wet weather discharges. Additional parameters will also be analyzed in accordance with Table 1. Small MS4 Monitoring Requirements, of Part N.A. in the MS4 General Permit. January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring The results of this evaluation will be used to assist the City in making informed decisions about whether to install a Downstream Defender° hydrodynamic separator, or equivalent device, in other locations. � LLV LIY V// l i Figure 1. Monitoring Sites 001 and 001a �.�. Site 002: Assess Future BMP Performance in Commercial/ Industrial Area Kalispell MS4 drainage area SWR-7 drains to the Stillwater River, which has an MS4 WLA for sediment. A monitoring location is located near the outfall of this watershed on Wyoming Street (see Figure 2). The drainage area is approximately 100 acres, comprised mostly of commercial/industrial land use. The City is planning to implement future BMPs within this drainage area in an effort to reduce the MS4's discharge of sediment to the Stillwater River. The monitoring results from samples collected before the BMPs are implemented within the drainage area (baseline samples) will establish the existing conditions. Future monitoring results will be compared to the baseline samples as BMP(s) are added within the drainage basin. The City plans to use the monitoring data results from this site to assess the BMP effectiveness in this immediate watershed (drainage area SWR-7) and develop a plan for installing BMPs in other commercial/industrial areas. January 9, 2018 3 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring LEGEND Monitoring Location Receiving Waterbody Figure 2. Monitoring Site 002 Site 004: Assess Future BMP Performance in Residential Area Kalispell MS4 drainage area AC-11 drains to Ashley Creek, which has an MS4 WLA for phosphorus, nitrogen, dissolved oxygen, sediment, and temperature. A monitoring location is located near the outfall of this watershed on 11t" Street West (see Figure 3). The drainage area is approximately 300 acres, comprised mostly of residential land use. The City is planning to implement future BMPs within this drainage area in an effort to reduce the MS4's discharge of pollutants to Ashley Creek. The monitoring results from baseline samples collected within the drainage area will establish the existing conditions. Monitoring results will be compared to the baseline data as BMP(s) are added within the drainage basin. The City plans to use the results of the monitoring data at this site to assess BMP effectiveness in this immediate watershed (drainage area AC-11) and plan future BMPs in other residential areas. A summary of all TMDL-related monitoring locations is provided in Table 2. For reference, Table 3 provides a summary of all self -monitoring locations where sampling will be conducted in accordance with Part IV of the MS4 General Permit. Comparison of Table 2 and Table 3 reveals that three of the self -monitoring locations will also be used for TMDL-related monitoring. This allows the City to be more efficient with collection of samples and analysis of monitoring data each year. January 9, 2018 4 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring a L O Storm Manhole • Monitoring Location Storm Main ------- Open Channel or Ditch Receiving Waterbody Figure 3. Monitoring Site 004 Table 2. TMDL-Related Monitoring Sample Locations 001 SWR-4 Stillwater 48°11'40.14"N Grab 4 Sediment River 114°17'55.76"W Stillwater 48°11'40.70"N 001a SWR-4 River Grab 4 Sediment 114°17'57.38"W 002 SWR-7 Stillwater 48°12'26.98"N Grab' 4 Sediment River 114'18'49.81"W 004 AC-11 Ashley 48'11'10.01"N Grab' 4 TP, TN, DO, Sediment, Creek 114°19'17.46"W Temperature ' A composite sample is the preferred sample collection method for this site; however, experience collecting grab samples at this site will help the City develop a better understanding of site conditions resulting in a more effective implementation plan and design for collecting composite samples in the future. The City will consider development of a composite sample collection and analysis plan for this site in the coming years. January 9, 2018 5 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring Table 3. Self -Monitoring Sample Locations Name Watershed Receiving Locatio Waterbody Stillwater 48°11'40.14"N 001 SWR-4 River 114°17'55.76"W 00 SWR-7 Stillwater 48°12'26.98"N River 114'18'49.81"W 003-A AC -A Ashley 48°11'43.49"N Creek 114°22'23.71 "W 004 AC-11 Ashley 48'11'10.01"N Creek 114°19'17.46"W Grab Semi-annual' ■ Total Suspended Solids ■ Chemical Oxygen Demand Grab Semi-annual' - Total Phosphorus ■ Total Nitrogen ■ pH ■ Copper Grab Semi-annual' - Lead ■ Zinc ■ Estimated Flow ■ Oil and Grease Grab Semi-annual' ' One sample must be collected between January 1It and June 30th of each permitted calendar year and the other sample between July 15t and December 315c 4 Monitoring Requirements Quality Assurance/Quality Control (QA/QC) is critical for accurate sampling. This section provides details of sampling methods, laboratory analytical methods, and QA/QC procedures to be used in sampling. 4.1. Field Sampling Methods The City will use manual sample collection techniques to conduct monitoring activities at each site in the immediate future. In the coming years, automated samplers will likely be used to collect composite samples at sites 002 and 004. Each of these methods are discussed below. 4.1.1 Manual Sample Collection Manual grab techniques will be used to collect samples at 001, 001 a, and 003' throughout the duration of this plan. The grab sample method is suitable for site's 001 and 001 a because samples will be collected within minutes of each other and since the hydraulic residence time that stormwater is in the BMP is only a few minutes, this approach will provide an accurate comparison of influent and effluent water quality for the Downstream Defender° hydrodynamic separator. A grab sample at site 003 will be used to evaluate the quality of water in Ashley Creek upstream of Kalispell's MS4. Manual grab techniques will also be used to collect samples at sites 002 and 004 in the immediate future; however, the City is considering the use of automated samplers to collect composite samples at these sites in the coming years (see Section 4.1.2). The samples will be collected by field personnel during rainfall events. Rainfall events will be monitored by weather surveillance radar so that field personnel can determine when to be present in the watershed during active events to obtain manual samples.2 Samples will be collected in clean, ' Site 003 is a self -monitoring site and will not be part of the TMDL-related monitoring. 2 Radar is available via the Nation Weather Service webpage https://radar.weather.gov/ridge/radar.php?rid=msx&product=NOR&overlav=l 1101111 &loop=no January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring labeled bottles provided by the laboratory. If necessary, an extension pole, rope or other apparatus can be used to aid the field crew in safe sample collection, especially during high flow conditions. 4.1.2 Automated Sample Collection If applicable, automated sampling devices will be used to collect composite samples; that is, small constant volume samples that are collected throughout a runoff event (as opposed to a manual grab sample, which only represents one point in time during an event). The City owns two ISCO 6712 automated sample devices which will likely be used to collect composite samples at site's 002 and 004 in the future. The primary monitoring objective at site's 002 and 004 is to assess the impact of future BMPs implemented upstream using sample data collected near the downstream -most point in a local watershed. Composite sampling is preferred for these locations because it would provide an event mean concentration of the pollutants from the runoff event; however, as noted above, additional experience and understanding of site conditions is needed to effectively and accurately collect and analyze composite samples. If automated sampling is implemented, the City expects that flow -weighted sampling would be used by collecting multiple aliquots (small samples) over the duration of the storm in one bottle which will be shipped to the Montana Environmental Laboratory for analysis following the storm event. 4.1.3 Sampling Equipment Decontamination Decontaminated sample collection bottles and lids will be provided by the laboratory. Sampling Parameters and Analytical Methods The water quality samples collected will be analyzed for the MS4 listed pollutants of impairment in the specific receiving waterbody as well as the parameters listed in Table 1 of Part IV.A in the MS4 General Permit (Small MS4 Monitoring Requirements). Table 4 shows the parameters and standard analytical methods to be used. All data should meet the precision, recovery, and accuracy requirements specified in the laboratory method used. The laboratory used for this study will maintain internal quality assurance/quality control procedures as documented in their laboratory quality assurance manual. The laboratory will use a combination of blanks, laboratory control spikes, surrogates, and duplicates to evaluate the analytical results. Sample Handling and Documentation Automatic samplers will be serviced immediately following a storm event. Chain of custody forms will accompany all samples. A Field Log will be kept for each sampling site with the details of the date, time, personnel, and purpose of visit, weather, and conditions observed, samples collected and actions performed. January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring Table 4. Analytical Methods Total Suspended SM 2540 D 1 Solids Total Phosphorus E365.1 0.01 Nitrogen — Kjeldahl, E351.2 0.2 total' Nitrate & Nitrite, E353.2 0.01 total' E300A 1 L plastic3 None Chemical Oxygen E410.1 1 Demand E410.4 Total Recoverable E200.8 0.01 Copper2 Total Recoverable E200.8 0.001 Lead2 Total Recoverable E200.7 0.01 Zinc2 E200.8 Oil and Grease2 E1664A 1 1 L glass (2) H2SO4 to pH<2 Cool to 4°C Estimated Flow2 N/A N/A N/A N/A Dissolved Oxygen SM 4500-OG 0.1 N/A N/A Temperature N/A 0.1°C N/A N/A Analyze immediately3 28 Analyze onsite4 Analyze onsite4 Analyze onsite4 PH E150.1 0.1 unit N/A N/A Analyze onsite ' Total Nitrogen is calculated from Nitrogen — Kjeldahl, total and Nitrate & Nitrite, total. 2 These parameters will only be analyzed semi-annually, in accordance with the City's self -monitoring plan. 3 Samples will be immediately delivered to the Montana Environmental Lab in Kalispell. The lab staff will separate the 1 L samples so that each parameter can be analyzed. Preservatives will be added by the lab staff, if necessary. 4 The City analyze for estimated flow, dissolved oxygen, temperature, and pH, onsite. 4.4. Storm Events and Sample Frequency Sampling will be attempted for measurable runoff events (that is a rainfall events that produce any volume of runoff flowing past/through the monitoring location that will allow a sample to be collected). In accordance with Part IV.a.6.a. of the MS4 General Permit, a minimum of one sample will be collected at each site between January 1 st and June 30th and a minimum of one sample will be collected at each site between July 1 st and December 31 st of each year. The City will attempt to January 9, 2018 8 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring collect four samples annually for MS4 listed impairments at each site (see Table 2).3 Four annual samples will provide greater assurance that data is representative. Precipitation will be monitored using a combination of on -site or web -based rain gauge s4, and the radar managed by the National Oceanic and Atmospheric Administration's Nation Weather Service. This data may be used to delineate storm characteristics, if necessary (timing, duration, intensity, and relative total rainfall). 4.5. Quality Assurance/Quality Control Samples will be analyzed using the designated EPA Method or Standard Method as defined in Table 4. Chain -of -custody procedures will be followed for samples sent to the laboratory. Analysis of Results All sample results will be compiled into a spreadsheet containing the results for each parameter at every sample site. The analysis method will vary depending on the sample collection method and site objectives, which are described in the subsequent sections. 4.6.1 Sample Collection at Sites 001 and 001a The objective at sample site's 001 and 001 a is to compare influent and effluent data for the Downstream Defender° hydrodynamic separator. BMP effectiveness will be quantified by calculating the percent change in pollutant concentration between the two sample sites, using Equation 1. The calculated percent change for each sample collected will be presented on a graph (sample date vs. percent change) to assess the long-term performance of the BMP. mim Percent Change= C'cce *100 Equation 1 C; = Influent concentration (mg/L) Ce = Effluent concentration (mg/L) 4.6.2 Sample Collection at Sites 002 and 004 A graph will be generated showing sample date (time) vs. concentration, for each parameter. These graphics will show the trend in water quality data over the period of time which samples are being collected. A downward trend will indicate that BMPs implemented upstream are effective, while a stagnant or upward trend would indicate the BMPs implemented upstream are not effective at reducing pollutants. A separate analysis of each parameter can be used to help understand the effectiveness of BMPs for a variety of parameters considered. 5 Reporting The results from TMDL-related monitoring will be presented and discussed in each year's MS4 annual report. The discussion will focus on the evaluation of the effectiveness of BMPs being implemented to address pollutants of impairment within each local watershed as well as changes in water quality over time. 3 Only two of the four annual samples will be analyzed for the full suite of self -monitoring parameters (listed in Table 1. Small MS4 Monitoring Requirements, of Part IV.A. in the MS4 General Permit). 4 The following websites provide historic rainfall data for the City of Kalispell: http://w2.weather.gov/climate/index.php?wfo=mso; http://mesowest.utah.edu/cqi-bin/droman/precip monitor.cgi?state=MSO&rawsflaq=3 January 9, 2018 City of Kalispell I Storm Water Management Program MS4 Sampling Plan for TMDL-Related Monitoring Appendix A. Supplemental Figures 4 _1 G n o fr C T � N Eo 'y coEm m Y%ok U Of U > N > m K a o �`° .— B aT .0 O - - . c m m J 'm U U `m m w T (n m N E 3� Q.�mQ mm °� �A 6 ol+. y N - = O 6) Y U m Q cn in 5 •—"f E Q ` �_ n s= u .o O o 3 Z Q.� v a Q � d J rc cn W u W_ IL Ei QJQ m Y >w }O} > F U z w U w C� C / 1 1 r ....l............ .l r r. - Ile r O A N O N O B E E— Q > 1 .� m d O w, C O N U > `O .a -a - 10 w K a K u o Q u u� s U U m w L° m :; o �'w i .o m E '� 0 s I, m -� -m_ 3N - - 0 Z .�.., E 8o-3 � 3v • O I 1��11� � ®Z w r..rQ `m `m��� o MPDES Permit # MTR04005 Evaluation of Stormwater Quality Monitoring 2019 Sample Results Introduction The City of Kalispell operates its storm drainage system under the authorization of the Montana Pollution Discharge Elimination System (MPDES) General Permit for Storm Water Discharges Associated with Small Municipal Separate Storm Sewer Systems (MS4s). The current MS4 General Permit, issued by the Montana Department of Environmental Quality (MDEQ), is effective from January 1, 2017 through December 31, 2021. Part IV of the MS4 General Permit requires semi-annual monitoring (self -monitoring). The City has selected self -monitoring Option 2 (see Part IV of the MS4 General Permit). Stormwater grab samples were collected semi-annually from four stormwater discharge locations within the City of Kalispell. Four discharge sample locations were chosen to represent stormwater runoff (1) from a primarily commercial/industrial area, (1) from a primarily residential area, (1) from a large drainage area combining both commercial and residential areas, and (1) upstream, outside the MS4 boundary to evaluate water quality entering the MS4 (Table 1). Drainage Name Watershed Receiving Waterbody Location Area (Acre) 001 SWR-4 Stillwater 48°11'40.14"N 266 Semi- Total Suspended p River 114°17'55.76"W annual Solids ■ Chemical Oxygen Stillwater 48°12'26.98"N Semi- Demand 002 SWR-7 River 114°18'49.81"W 100 annual ■ Total Phosphorus ■ Total Nitrogen ■ pH 003A AC -A Ashley 48°11'43.49"N NA Semi- Copper pp Creek 114°22'23.71"W annual 0 Lead ■ Zinc Ashley 48°11'10.01"N Semi- Estimated Flow 004 AC-11 Creek 114°19'17.46"W 294 annual ■ Oil and Grease Methods Sample Collection Grab samples were collected once in the spring (4/9/19) and once in the fall (9/9/19) of 2019. Field personnel collected samples during rainfall events that produced a measurable volume of runoff flowing past/through the monitoring locations that allowed a sample to be collected. Clean, labeled bottles provided by the laboratory, on an extension pole, were used to obtain stormwater samples. Field logs were used to document the date, time, location, personnel, weather, conditions observed, samples collected, estimated duration of the storm event, and total rainfall of the storm event. Sample Parameters and Analytical Methods Stormwater samples were analyzed for the parameters listed in Table 1. Table 2 shows the parameters and the standard analytical methods used. Montana Environmental Labs processed all the samples and uses a combination of blanks, laboratory control spikes, surrogates, and duplicates to evaluate analytical results. Chain of custody forms accompanied all samples. Sample Analysis Due to new sample locations being designated in 2017, statistical analyses are not appropriate because of the low number of samples. The City of Kalispell is required to calculate the long- term median concentration of all known monitoring results at an individual location of each parameter in Table 1 Par N.A. of the MS4 General Permit issued by MDEQ. To compare individual parameters across locations, bar charts were created to visually represent observed sample values of 2019 in comparison to the long-term median. To compare parameters at one location, parameter values were standardized and graphed over time by location. The MS4 General Permit requires monitoring results to be used to evaluate measures taken to improve the quality of stormwater discharges. This includes an evaluation of the results relative to the long-term median, comparisons between monitoring locations, discussion of trends and outliers compared to the long-term median, discussion of pH values outside the range of 6.0 to 9.0, and a schedule and rationale for BMPs planned to improve water quality of stormwater discharges based on monitoring results. 2 Table 2. Parameters and standard analytical methods Total Suspended SM 2450 D• va Solids Total Phosphorus E365.1 0.01 Nitrogen — Kjeldahl, i total E351.2 0.2 Nitrate & Nitrite, E353.2 totals E300A 0.01 Chemical Oxygen E410.1 1 Demand E410.4 Total Recoverable E200.8 0.01 Copper Total Recoverable E200.8 0.001 Lead Total Recoverable E200.7 0.01 Zinc E200.8 Oil and Grease E1664A 1 Estimated Flow NA NA Dissolved Oxygen SM 4500-OG 0.1 2 2 1 L plastic None 1 L glass (2) H2SO4 to pH<2 Cool to 4°C NA NA NA NA Temperature NA 0.1°C NA NA Analyze immediately2 28 3 Analyze onsite 3 Analyze onsite 3 Analyze onsite pH E150.1 0.1 unit NA NA Analyze onsite3 'Total Nitrogen is calculated from Nitrogen — Kjeldahl, total and Nitrate & Nitrite, total. 2 Samples will be immediately delivered to the Montana Environmental Lab in Kalispell. The lab staff will separate the 1L samples so that each parameter can be analyzed. Preservatives will be added by the lab staff, if necessary. 'The City analyzes estimated flow, dissolved oxygen, temperature, and pH, onsite. 3 Results Sample Comparison and Median Concentration Table 3 is a summary of the 2019 sample parameter comparisons with the long-term median concentrations for each. Long-term median concentrations are calculated from all known monitoring results for each parameter at a monitoring location. Please note, as monitoring locations were new in 2017, median concentrations have been calculated only with samples taken since 2017 (6 total samples per site). Figures 1-9 depict observed and median parameter concentrations by site location. Many of the sites had higher recorded parameter values in spring than fall. Zinc was greater for all stormwater sampling locations collected in the spring (zinc was not detected at AC-A/003A, the in -stream sample). Total phosphorus (TP), pH, chemical oxygen demand (COD), total nitrogen (TN), copper, and lead were greater in the spring for all locations except for AC-A/003A (TP, COD, TN, copper, lead) and AC-11/004 (pH). Total suspended solids (TSS) was greater in the spring for all locations except AC-A/003A where it was equivalent for both sampling events. Oil and grease values were greater in spring at both locations discharging to the Stillwater River (SWR-4/001, SWR-7/002), not detected in spring and fall at AC-A/003A, and greater in fall at AC- 11/004. Flow was greater in fall for all locations. In the spring, observed parameter values somewhat to notably elevated include TSS, oil/grease, and COD at SWR-4/001 and TSS and COD at SWR-7/002. 4 �a wi U, � O �7 Lr L N LID ry R ry z zz on W-1 rl. LO Ln r, M Ln N U) N r, u7 ° La o q en un LO z ° N c3 sa 0 .� ff� Eq R L, ,o 0 0 0 0 0 0 0 0 0 0 U, ° N cc [a c 0 fa D_0 D� +� L 4� 4i Zh ZP F O re b w 4i 0 m F� m m m m -0 F= F= C C b o� u u u u u u M1 M1 r`I r`I OC OC OC OC � � rl rl O E on O O_ v L v U v o z u 0 z 5 600 500 400 J 00 £ 300 N N H 200 100 0 OBSERVED & MEDIAN TSS SWR-4 SWR-4 4/9/19 9/9/19 SWR-7 SWR-7 AC -A AC -A 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION AC-11 AC-11 4/9/19 9/9/19 Figure 1. Observed (2019) and median (2017-2019) TSS (total suspended solids) concentrations by location. Horizontal red lines represent median concentrations. OBSERVED & MEDIAN COD 350 300 oW, J 200 E 0 150 U 100 50 0 SWR-4 SWR-4 SWR-7 SWR-7 AC -A AC -A AC-11 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 LOCATION Figure 2. Observed (2019) and median (2017-2019) COD (chemical oxygen demand) concentrations by location. Horizontal red lines represent median concentrations. AC-11 9/9/19 11 OBSERVED & MEDIAN TP 0.5 0.45 0.4 0.35 0.3 ono E 0.25 0.2 0.15 0.1 0.05 0 SWR-4 SWR-4 SWR-7 SWR-7 AC -A AC -A AC-11 AC-11 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION Figure 3. Observed (2019) and median (2017-2019) TP (total phosphorus) concentrations by location. Horizontal red lines represent median concentrations. OBSSERVED & MEDIAN TN 3 2.5 2 J M E 1.5 z 1 0.5 0 SWR-4 SWR-4 SWR-7 SWR-7 AC -A AC -A AC-11 AC-11 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION Figure 4. Observed (2019) and median (2017-2019) TN (total nitrogen) concentrations by location. Horizontal red lines represent median concentrations. 7 9 8.8 8.6 8.4 8.2 x 8 a 7.8 7.6 7.4 7.2 7 6.8 OBSERVED & MEDIAN PH SWR-4 SWR-4 SWR-7 SWR-7 AC -A AC -A AC-11 AC-11 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION Figure 5. Observed (2019) and median (2017-2019) pH values by location. Horizontal red lines represent median concentrations. OBSERVED & MEDIAN OIL & GREASE 18 16 14 J 00 12 E N 10 w a 8 C7 6 O 4 2 0 SWR-4 SWR-4 4/9/19 9/9/19 SWR-7 SWR-7 AC -A AC -A 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION AC-11 AC-11 4/9/19 9/9/19 Figure 6. Observed (2019) and median (2017-2019) oil and grease concentrations by location. Horizontal red lines represent median concentrations. U., OBSERVED & MEDIAN COPPER 0.035 0.03 0.025 J E 0.02 W as 0.015 O U 0.01 0.005 0 SWR-4 SWR-4 SWR-7 SWR-7 AC -A AC -A AC-11 AC-11 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 4/9/19 9/9/19 LOCATION Figure 7. Observed (2019) and median (2017-2019) copper concentrations by location. Horizontal red lines represent median concentrations. 0.018 0.016 0.014 0.012 J £ 0.01 Q 0.008 W J 0.006 0.004 0.002 0 SWR-4 4/9/19 OBSERVED & MEDIAN LEAD I SWR-4 9/9/19 ■ ■ SWR-7 SWR-7 AC -A 4/9/19 9/9/19 4/9/19 LOCATION AC -A AC-11 AC-11 9/9/19 4/9/19 9/9/19 Figure 8. Observed (2019) and median (2017-2019) lead concentrations by location. Horizontal red lines represent median concentrations. PEI 0.3 0.25 0.2 J M £ 0.15 U Z N 0.1 0.05 0 SWR-4 4/9/19 OBSERVED & MEDIAN ZINC I SWR-4 SWR-7 SWR-7 9/9/19 4/9/19 9/9/19 AC -A AC -A 4/9/19 9/9/19 IXGIGYAIIs] ►I AC-11 AC-11 4/9/19 9/9/19 Figure 9. Observed (2019) and median (2017-2019) zinc concentrations by location. Horizontal red lines represent median concentrations. Standardized Parameter Concentrations by Location Figures 10-13 compare sample parameters at one site over time. Parameters have been standardized to make the variables comparable. At most locations, many parameters co -vary together. Stormwater sample locations (SWR- 4/001, SWR-7/002, AC-11/004) appear to have elevated values in spring and lower values in fall. The parameter values at the in -stream location (AC-A/003), generally, do not fluctuate as much as the stormwater samples. The elevated TSS and oil and grease at SWR-4/001 on 4/13/18 appear to strongly co -vary, while the elevated TP at AC-11/004 on 4/13/18 does not strongly co -vary with any other parameters. Standardized parameters in 2019 did not see as large of fluctuations as 2018. 10 SWR-4 - RESIDENTIAL 30%, COMMERCIAL 70% tTSS (mg/L) fpH DTP (mg/L) —M—COD (mg/L) —*—TN (mg/L) tCopper (mg/L) t Lead (mg/L) Zinc (mg/L) Oil & Grease (mg/L) t Flow (GPM) 5 v) 4 w J Q > 3 or w F w g 2 or Q � 1 0 w N J cQ 0 of 0 Z -1 da 6/13/2017 11/22/2017 4/13/2018 11/2/2018 4/9/2019 9/9/2019 Figure 10. Standardized parameter values over time at SWR-4/001. SWR-7 - COMMERICAL/INDUSTRIAL tTSS (mg/L) f pH —DTP (mg/L) —M—COD (mg/L) —*—TN (mg/L) Copper (mg/L) Lead (mg/L) Zinc (mg/L) Oil & Grease (mg/L) Flow (GPM) 4 '^w 3 J Q > WK 2 F cW G cc 1 d 0 W J 0 cQ cc cc 0 -1 -2 6/13/2017 11/22/2017 4/13/2018 11/2/2018 4/9/2019 9/9/2019 Figure 11. Standardized parameter values over time at SWR-7/002. 11 tTSS (mg/L) Copper (mg/L) 4 W 3 J Q > z 2 W H cW G Q 1 Cl- 0 W J 0 cQ G AC -A - IN -STREAM fpH -*—TP (mg/L) COD (mg/L) —Mt—TN (mg/L) Lead (mg/L) Zinc (mg/L) Oil & Grease (mg/L) --*---Flow (GPM) -2 6/13/2017 11/22/2017 4/13/2018 11/2/2018 4/9/2019 9/9/2019 Figure 12. Standardized parameter values over time at AC-A/003 (2017-2018) and AC- A/003A (2019). tTSS (mg/L) tCopper (mg/L) 5 V) 4 W Q 3 Uj W 2 Q1 a LU 0 N J Q 0 Z -2 -3 AC-11 - RESIDENTIAL fpH —DTP (mg/L) --*(--COD (mg/L) —Mt—TN (mg/L) t Lead (mg/L) Zinc (mg/L) Oil & Grease (mg/L) --*---Flow (GPM) 6/13/2017 11/22/2017 4/13/2018 11/2/2018 4/9/2019 9/9/2019 Figure 13. Standardized parameter values over time at AC-11/004. 12 Discussion: Trends, Outliers, and BMPs The following analysis reviews the 2019 parameter trends and outliers compared to the calculated long-term median and examines results outside a pH range of 6.0 to 9.0 standard units. Additionally, explained is a schedule and rationale for BMPs planned to improve the water quality of stormwater discharges based on monitoring results. Sampling Conditions Spring samples were collected in April 2019. The winter leading up to this sample collection had numerous snow events, which lead to frequent sanding and salt application. Fall samples were collected in September 2019. Prior to sample collection, the summer was generally cool with some small rain showers. The September event began with heavy rainfall in the very early morning. Samples were collected at the beginning of the workday. Spring samples generally had higher concentrations of all parameters. This same pattern was observed in the 2017 and 2018 sample results. This may be indicative of winter loading of contaminants. Additional measures to try to reduce spring runoff may be beneficial. Future sampling will help clarify trends and what BMPs will be most beneficial to minimize pollutant discharge. Stillwater River Two locations drain into the Stillwater River, which is listed as impaired for sediment. Location 001-SWR-4 is characterized as mixed residential (30%) and commercial (70%) and location 002- SWR-7 is characterized as commercial/industrial. Mixed Residential (30%) and Commercial (70%) Location Sample location 001-SWR-4 drains about 266 acres and had elevated total suspended solids, oil/grease, and chemical oxygen demand in the spring samples in 2018 and 2019. However, the 2019 samples all had lower pollutant concentrations per season than 2018. In 2018, due to the elevated TSS and oil and grease, the surrounding storm system was inspected and cleaned. This sample location is downstream from two mechanical treatment units. Both treatment units were cleaned along with upstream manholes and sumps (if needed). A roll of Ram-Nek/manhole mastic was found in a manhole sump upstream and was removed. This could have been contributing to higher oil and grease and COD readings in spring 2018. The cleaning schedule of the two treatment units was updated to twice a year due to the amount of debris found when they were cleaned, and the biannual schedule has been maintained. After the wide -scale cleaning in 2018, TSS, oil and grease, and COD levels dropped during the next sampling event and have continued to stay below the spring 2018 levels. Commercial/Industrial Location At sample location 002-SWR-7, the median of every parameter, except TP and TN, was higher than other locations in both 2018 and 2019. The drainage area of 002-SWR-7 is approximately 100 acres and is comprised mostly of commercial/industrial land use 13 including highway managed by Montana Department of Transportation. Activities in industrial areas and highways, including material handling and storage, equipment maintenance and cleaning, and others, are often exposed to weather and may introduce pollutants into stormwater. Total suspended solids and chemical oxygen demand readings were elevated, though not as high as 001-SWR-4. All parameters will be monitored to try and further understand sources. Future sampling may help clarify trends and outliers at this location and what management practices will provide a reduction of the pollutant loads. The City's Capital Improvement Program has a stormwater quality treatment facility planned for 2020 to try to reduce the MS4's discharge of sediment to the Stillwater River. Samples collected prior to implementation may provide information on BMP effectiveness in a commercial/industrial location and help plan future BMPs in other commercial/industrial areas. Ashley Creek Two locations drain into Ashley Creek, which is listed as impaired for phosphorus, nitrogen, dissolved oxygen, sediment, and temperature. Location 003A-AC-A is characterized as being in - stream and outside the MS4 boundary and 004-AC-11 is characterized as residential. In -Stream Outside MS4 Boundary Location Sample location 003A-AC-A did not have notable trends or outliers in monitoring results compared to the calculated long-term median. The in -stream sample results provide background readings of the pollutants in -stream during comparable rain events. Residential Location The drainage area of 004-AC-11 is approximately 300 acres, comprised mostly of residential land use. Sample location 004-AC-11 results showed moderate levels of total suspended sediment, chemical oxygen demand, total phosphorus, and total nitrogen. In 2018, total phosphorus was significantly elevated in the spring sample but was comparable to other sites in 2019. Future sampling may help clarify trends and outliers at this location and what management practices will provide a reduction of the pollutant loads. The City's Capital Improvement Program has a stormwater quality treatment facility planned for 2023 to try to reduce the MS4's discharge of pollutants to Ashley Creek. Samples collected prior to implementation may provide information on BMP effectiveness in a residential location and help plan future BMPs in other residential areas. Identified Pollutants Several pollutants were identified as elevated through this evaluation. As such, this section provides a schedule and rationale of BMPs planned to improve the water quality of the stormwater discharges. 14 Chemical Oxygen Demand (COD) Potential Sources Natural: • Leaves and woody debris • Dead plants and animals Industrial: • Oils and grease from transportation and industrial/commercial site activities • Benzene from gasoline • Synthetic detergents Residential: • Grass clippings and leaves • Animal waste • Failing septic systems • Animal manure • Pesticides • Herbicides • Wood preservatives • Synthetic organic industrial chemicals • Sugar -containing substances (milk, molasses, juice, vegetables, energy drinks, etc.) Management Measures and BMPs Table 4 outlines the potential sources, reasons, and management measures the City has or will implement for the MPDES MS4 permit. Dry weather screening will continue to be utilized to aid in identifying sources of chemical oxygen demand. Additionally, two locations have a planned stormwater quality treatment facility in the City's Capital Improvement Program. Table 4. COD Evaluation 1 Public Education Program 2015-Current Implement Pollution Prevention Good Housekeeping Guidance Manual for Kalispell Municipal Operations. 2015-Current Fallen Leaves Provide training to City Organic material Landscaping employees. i.e. leaves, grass clippings Pre -Winter 6 Street Sweeping Program 2015-Current Maintenance Leaf Collection Program 2015-Current Storm Drainage System 2015-Current Inspection and Cleaning Residential Curbside Pickup Services 2013 Current * Minimum Measures 1) Public education and outreach on stormwater impacts; 2) Public involvement/participation; 3) Illicit discharge detection and elimination; 4) Construction site stormwater runoff control; 5) Post -construction stormwater management in new development and redevelopment; and, 6) Pollution prevention and good housekeeping for municipal operations. 15 Total Suspended Solids (TSS) Potential Sources Natural: • Erosion Industrial: • Land development • Roadway material deterioration • Road salt and sand Residential: • Land development • Road salt and sand • Road paint • Industrial/commercial site activities • Gravel parking areas • Road paint • Roadway material deterioration Management Measures and BMPs Table 5 outlines the potential sources, reasons, and management measures the City has implemented or will implement for the MPDES MS4 General Permit. Additionally, two locations have a planned stormwater quality treatment facility in the City's Capital Improvement Program. 16 Table 5. TSS Evaluation Irlimimurn x. Potential Sources Reasons Measure BMP Implemented Ordinance 1831: Stormwater Regulations. Requires Construction 2015- Stormwater Permits for all land Current 4 disturbance within City limits. Subdivision Development Provide training for builders, 2015- engineers, and developers. Current Residential House 2015- Construction Public Education Program Current Construction Site Runoff Municipal Operations 1 Public Education Program 2010 g 2010- Update to include commercial Commercial education. Current Implement Pollution Prevention Development Good Housekeeping Guidance 6 Manual for Kalispell Municipal Current Operations. Provide training to City employees. Implement Pollution Prevention Good Housekeeping Guidance Manual for Kalispell Municipal Current Operations. Sand on Roads Winter condition road 6 Provide training to City employees. sanding Street Sweeping 2015- Current Storm Drainage System Inspection & 2015- Cleaning Current Generation of solid 1 Public Education Program 2015- material from industrial Current Industrial and and commercial site Illicit Discharge, Detection, and 2015- Commercial activities 3 Elimination Program Current Sites Dirt/gravel driveways Redevelopment standards 2015- 5 implemented through Kalispell and parking areas Design and Construction Standards Current Yard Waste Management 1 Public Education Program 2018- Current Residential Native Landscaping Better Car and Equipment 6 Residential Curbside Pickup Services p 2013- Current Washing Commercial Yard Waste Management 1 Public Education Program Landscaping Current Current * Minimum Measures 1) Public education and outreach on stormwater impacts; 2) Public involvement/participation; 3) Illicit discharge detection and elimination; 4) Construction site stormwater runoff control; 5) Post -construction stormwater management in new development and redevelopment; and, 6) Pollution prevention and good housekeeping for municipal operations. 17 Oil and Grease Potential Sources Natural: ■ Petroleum Industrial: ■ Automotive oils Residential: ■ Automotive oils ■ Cooking oils Management Measures and BMPs Table 6 outlines the potential sources, reasons, and management measures the City has implemented or will implement for the MPDES MS General Permit. Additionally, two locations have a planned stormwater quality treatment facility in the City's Capital Improvement Program. Table 6. Oil and Grease Evaluation *Mi.. •. Measure Implemented Public Education Program 2007-Current 1 Public Education Program Industrial Site Common industrial and 2010 Update to include 2010-Current Activities commercial site activities commercial education Illicit Discharge, Detection, 3 2008-Current and Elimination Program Restaurants Common restaurant activities 1 Public Education Program 2013-Current Residential Car Maintenance 1 Public Education Program 2018-Current Mobile Cleaning Common mobile cleaning Business activities (i.e. pressure washing) 1 Public Education Program 2018 Current Gas Stations Common gas station activities 1 Public Education Program 2018-Current * Minimum Measures 1) Public education and outreach on stormwater impacts; 2) Public involvement/participation; 3) Illicit discharge detection and elimination; 4) Construction site stormwater runoff control; 5) Post -construction stormwater management in new development and redevelopment; and, 6) Pollution prevention and good housekeeping for municipal operations. 18 APPENDIX A. Monitoring Parameters The parameters required to be monitored can contribute to stormwater pollution. The following is a description of the potential sources of stormwater runoff contamination. Total Suspended Solids (TSS) TSS is a common stormwater pollutant and can be generated from construction sites, bare spots in lawns and gardens, wastewater from washing/trucks on driveways and parking lots, dirt roads and driveways, and sanding roads during winter conditions. Chemical Oxygen Demand (COD) Organic material such as leaves, grass, oils, grease, and litter become deposited in urban areas and become part of stormwater runoff flows. A COD test can be used to quantify the amount of organics in water. COD is a measure of the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as Ammonia and nitrite. High COD concentrations lower dissolved oxygen concentration, progressively deteriorating conditions for fish and other aquatic life. Also, the absence of dissolved oxygen could result in the growth of microorganisms that produce by-products which cause foul odors in the water. Total Phosphorus (TP) Nutrients such as phosphorus are common constituents of nonpoint source runoff. The introduction of nutrients into receiving waters stimulates the growth of algae and other aquatic plants causing algal blooms and creating turbid conditions. Total phosphorus enters runoff from sources such as fertilizers, pesticides, grass clippings/leaves left on streets and sidewalks, detergents and washing fluids, animal waste, and seepage from septic tanks. Automobile lubricant emissions, food products, and various household cleaners, paints, fabrics and carpets contain phosphates which can also be transported by runoff. Total Nitrogen (TN) Plant nutrients, such as nitrogen, are common constituents of nonpoint source runoff. The introduction of nutrients into receiving waters stimulates the growth of algae and other aquatic plants causing algal blooms and creating turbid conditions. Total nitrogen enters runoff from sources such as fertilizers, grass clippings and leaves left on streets and sidewalks, detergents and washing fluids, animal wastes, and seepage from septic tanks. pH Most discharge flow types are neutral, having a pH value around 7, although groundwater concentrations can be somewhat variable. pH is a reasonably good indicator for liquid wastes from industries, which can have very high or low pH (ranging from 3 to 12). The pH of residential wash water tends to be rather basic (pH of 8 or 9). Although pH data is often inconclusive by itself, it can identify problem outfalls that merit follow-up investigations using indicators that are more effective. Heavy Metals: Total Copper (Cu), Lead (Pb), Zinc (Zn) Metal pollutants can be generated from the operation and maintenance of motor vehicles, the degradation of highway material, and industrial/commercial site activities. Heavy metals in 19 water can cause bioaccumulation in animal tissues, affect reproduction rates and life spans of aquatic species, and ultimately affect recreational and commercial fisheries. Transportation - related sources of Zn include diesel fuel, crankcase and lubrication oils, grease, and decorative and protective coatings. Copper in stormwater runoff can be generated from wear on brake pads, roofing and gutter runoff, and copper -based fungicides/fertilizers used for controlling algae, fungi, and mildew. Metal finishers, electroplaters, and semiconductor manufacturers may use copper -containing materials in their manufacturing processes. Vehicle services (engine repair and service, fueling, vehicle body repair, replacement of fluids, recycling, cleaning, and outdoor equipment storage and parking through dripping engines) can generate toxic hydrocarbons and other organic compounds, oils and greases, nutrients, phosphates, heavy metals, paints and other contaminants. Radiator repair and flushing operations are the most likely source of copper - containing waste streams. The principal source of lead in highway and street stormwater runoff as well as soils in urban areas and near highways during the time of the NURP studies i.e., about 1980, was the use of lead as an additive in gasoline. Other sources of lead in stormwater runoff include yellow and white road marking paints used on parking lots, streets, buildings, building cavity dust and other demolition waste from buildings and structures, and vehicular sources including leaded petrol (auto exhaust), auto paint (which can still contain 10% lead), lead -acid batteries, lubricating oil and grease, and bearing wear. Oil and Grease (O&G) Oil and grease pollutants can be generated from leaks and spills of oil and gas, used oil dumping, and commercial and industrial activities. These organic pollutants cannot be easily decomposed through biological action and may persist for long periods. c APPENDIX B. Correlation Matrix 0091, 0 t, 0 9'8 0'L 000'0 91, 0 0 o i i o i i 30 co F O O c c O o 0 0 0 o O � N 0 � O 0 o O o O o o ao a M O Lfi o Oe O W � v O p o N O o 0 0 0 8 0 a o 0 o � o 0 0 0 0 0 0 o d O O O 0 0 0 ® o 00 0 0 co O O r O c, O O O 0 8 0 CO O O a I �00 a a ooa � q q 4 0 0 M 0 � O O ti ti ti ti rn � co N CD CD O co a o 00 ti O OO ti o QS O o O O O O CD 0 co ti ti o co O o o O O O o 4 O oot, 0 s 1, 00'0 00'o 0000s o Figure 131. Correlation matrix of water quality variables. Correlations (r) are represented on the lower left, histograms on the diagonal, and x-y plots on the upper right. TSS = total suspended solids, COD = chemical oxygen demand, TP = total phosphorus, TN = total nitrogen, Cu = total copper, Pb = total lead, Zn = total zinc, OG = oil and grease 21