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[[File:Monitoring 3.png|300px|thumb|alt=lake monitoring image|<font size=3>Example of lake monitoring. Photo courtesy of MPCA's Flickr site.</font size>]]
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The primary reasons for a permittee to perform monitoring of receiving waters are to (a) evaluate the impact of TMDL implementation strategies enacted throughout the watershed, and (b) evaluate impairment status to determine if the impaired waterbody can be removed (i.e., delisted) from the 303(d) Impaired Waters List. The following subsections outline the basics of developing a monitoring program to meet goals established within the  [https://www.pca.state.mn.us/sites/default/files/wq-iw1-04i.pdf Guidance Manual for Assessing Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report] and 303(d) List (MPCA, 2018a), and developing a monitoring protocol <span title="a set of step-by-step instructions to help workers carry out complex routine operations. SOPs aim to achieve efficiency, quality output and uniformity of performance, while reducing miscommunication and failure to comply with industry regulations."> '''standard operating procedure'''</span> (SOP). Specifically, the [https://stormwater.pca.state.mn.us/index.php?title=Recommendations_and_guidance_for_utilizing_monitoring_to_meet_TMDL_permit_requirements#Establishing_a_Monitoring_Program Establishing a Monitoring Program] section provides guidance on when, where, and what to sample, while the [https://stormwater.pca.state.mn.us/index.php?title=Recommendations_and_guidance_for_utilizing_monitoring_to_meet_TMDL_permit_requirements#Establishing_a_Monitoring_Protocol Establishing a Monitoring Protocol] section provides guidance on how to sample (i.e., sampling SOP).  
 
The primary reasons for a permittee to perform monitoring of receiving waters are to (a) evaluate the impact of TMDL implementation strategies enacted throughout the watershed, and (b) evaluate impairment status to determine if the impaired waterbody can be removed (i.e., delisted) from the 303(d) Impaired Waters List. The following subsections outline the basics of developing a monitoring program to meet goals established within the  [https://www.pca.state.mn.us/sites/default/files/wq-iw1-04i.pdf Guidance Manual for Assessing Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report] and 303(d) List (MPCA, 2018a), and developing a monitoring protocol <span title="a set of step-by-step instructions to help workers carry out complex routine operations. SOPs aim to achieve efficiency, quality output and uniformity of performance, while reducing miscommunication and failure to comply with industry regulations."> '''standard operating procedure'''</span> (SOP). Specifically, the [https://stormwater.pca.state.mn.us/index.php?title=Recommendations_and_guidance_for_utilizing_monitoring_to_meet_TMDL_permit_requirements#Establishing_a_Monitoring_Program Establishing a Monitoring Program] section provides guidance on when, where, and what to sample, while the [https://stormwater.pca.state.mn.us/index.php?title=Recommendations_and_guidance_for_utilizing_monitoring_to_meet_TMDL_permit_requirements#Establishing_a_Monitoring_Protocol Establishing a Monitoring Protocol] section provides guidance on how to sample (i.e., sampling SOP).  
  
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==Monitoring requirements: lakes==
 
==Monitoring requirements: lakes==
[[File:Monitoring 3.png|300px|thumb|alt=lake monitoring image|<font size=3>Example of lake monitoring. Photo courtesy of MPCA's Flickr site.</font size>]]
 
 
[[File:Monitoring 4.png|300px|thumb|alt=lake monitoring image|<font size=3>Monitoring a lake impaired for eutrophication. Photo courtesy of MPCA's Flickr site.</font size>]]
 
[[File:Monitoring 4.png|300px|thumb|alt=lake monitoring image|<font size=3>Monitoring a lake impaired for eutrophication. Photo courtesy of MPCA's Flickr site.</font size>]]
 
[[File:Monitoring 5.png|300px|thumb|alt=image of secchi disk|<font size=3>Photo of sampling with a secchi disk. Photo courtesy of MPCA's Flickr site.</font size>]]
 
[[File:Monitoring 5.png|300px|thumb|alt=image of secchi disk|<font size=3>Photo of sampling with a secchi disk. Photo courtesy of MPCA's Flickr site.</font size>]]

Revision as of 15:38, 23 September 2019

This site is currently undergoing final review. For more information, open this link.
This page is under review
lake monitoring image
Example of lake monitoring. Photo courtesy of MPCA's Flickr site.

The primary reasons for a permittee to perform monitoring of receiving waters are to (a) evaluate the impact of TMDL implementation strategies enacted throughout the watershed, and (b) evaluate impairment status to determine if the impaired waterbody can be removed (i.e., delisted) from the 303(d) Impaired Waters List. The following subsections outline the basics of developing a monitoring program to meet goals established within the Guidance Manual for Assessing Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report and 303(d) List (MPCA, 2018a), and developing a monitoring protocol standard operating procedure (SOP). Specifically, the Establishing a Monitoring Program section provides guidance on when, where, and what to sample, while the Establishing a Monitoring Protocol section provides guidance on how to sample (i.e., sampling SOP).

Establishing a Monitoring Program

Before developing or implementing a lake monitoring program, the applicable TMDL(s) should be reviewed to determine (a) if an ongoing water quality monitoring program exists or will be implemented and (b) what organization(s) are responsible for water quality monitoring (e.g., individual permitteess, the applicable Watershed District or Watershed Management Organization (WMO), etc.). Review of ongoing and planned water quality monitoring programs can help a permittee optimize sampling procedures to supplement ongoing monitoring efforts and help identify potential partnering opportunities with other organizations (e.g., WDs, WMOs, Citizen-Assisted Monitoring Program (CAMP), Soil and Water Conservation Districts (SWCDs), Metropolitan Council, etc.). To encourage statewide water quality monitoring efforts, the MPCA offers Surface Water Assessment Grants (SWAG) to eligible partners, including MS4s. More information on SWAG requirements and grant application can be found on the MPCA’s Surface Water Assessment Grants webpage.

In addition to review of planned or ongoing monitoring programs, the applicable TMDL(s) should be reviewed to determine the specific water quality standard(s) that apply to the impaired waterbody. Water quality standards applicable to the impaired waterbody are specific to the pollutant (e.g., chloride), the water body type (e.g., lake), and the water use classification (e.g., Class 2A).

Monitoring requirements: lakes

lake monitoring image
Monitoring a lake impaired for eutrophication. Photo courtesy of MPCA's Flickr site.
image of secchi disk
Photo of sampling with a secchi disk. Photo courtesy of MPCA's Flickr site.

The following subsections outline specific lake monitoring program requirements related to each of the four (4) pollutants discussed on this page: total suspended solids (TSS), total phosphorus (TP), bacteria, and chloride.

Total suspended solids (TSS)

As of 2018 Minnesota Impaired Waters List (MPCA, 2018b) there are no lakes listed as impaired for TSS. For more information regarding establishing a TSS monitoring program for streams, link here.

Eutrophication standard: lakes (TP, chlorophyll-a, and Secchi disk transparency)

Lake eutrophication water quality standards established in the Minnesota Rule, Chapter 7050 (MINN. R. 7050, 2018) require paired observations of TP, chlorophyll-a, and Secchi disk transparency during the summer period (June 1 through September 30) of the monitoring year. From Part 7050.0222, Subp. 2a:

Eutrophication standards for lakes and reservoirs are compared to summer-average data. Exceedance of the total phosphorus and either the chlorophyll-a or Secchi disk transparency standard is required to indicate a polluted condition.

The numeric standards for TP, chlorophyll-a, and Secchi disk transparency vary by use classification (e.g., Class 2B), ecoregion (e.g., North Central Hardwood Forests), and by lake classification (e.g., trout lake, shallow lake, etc.). The applicable water quality standards for the impaired waterbody are outlined in the applicable TMDL report. Based on Minnesota lake eutrophication standards and specific impairment assessment and delisting requirements for lake eutrophication, the following list outlines specific recommendations to develop a lake eutrophication monitoring program. Specific monitoring protocol recommendations are discussed here.

Lake Eutrophication Monitoring Program Recommendations

  • Number of samples per year:
    • Minimum: eight (8) paired samples of TP, chlorophyll-a, and Secchi disk over a minimum of a 2 year period within the most recent 10 years.
    • Recommended: four (4) or more paired samples of TP, chlorophyll-a, and Secchi disk transparency collected between June 1 and September 30 per year on an ongoing basis to continually monitor and evaluate lake eutrophication. Sampling dates should be selected and fixed before the monitoring season to remove sampling bias in selected monitoring dates. Monitoring should, to the extent possible, be collected at equal intervals throughout the period of June 1 to September 30 (i.e., sampling should capture seasonal changes in water quality).
  • Seasonal monitoring requirements: Samples must be collected between June 1 and September 30 of the sampling year.
  • Sampling location(s): Selected sampling locations should be consistent with sampling locations used to originally define impairment. Sampling locations used to define impairment may be outlined within the applicable TMDL(s). If not, contact MPCA to determine sampling location used to define impairment.
  • Sampling protocol (i.e., sample collection guidance): link here.

Bacteria (E. coli)

As of the 2018 Minnesota Impaired Waters List (MPCA, 2018b) there are no lakes listed as impaired for Escherichia coli (E. coli). For more information regarding establishing an E. coli monitoring program for streams, link here.

Chloride

Chloride water quality standards within Minnesota Rule, Chapter 7050 (MINN. R. 7050, 2018) are consistent for all Minnesota waters (i.e., all use classifications). Specifically, Minnesota Rules define a chronic toxicity-based chloride water quality standard of 230 mg/L (i.e., chronic standard), and an acute toxicity standard of 860 mg/L (i.e., maximum standard). Specific data requirements for evaluation of impairment condition for both the chronic and maximum chloride water quality standard established in the Guidance Manual for Assessing the Quality of Minnesota Surface Waters for Determination of Impairment: 305(b) Report and 303(d) List (MPAC, 2014) are outlined below.

  • Chronic standard (230 mg/L):
    • Exceedances of chronic standards for toxic pollutants are evaluated over a consecutive three year period.
    • Two or more exceedances of the chronic standard in three years is considered an impairment.
    • Chronic water quality standards are defined as a four (4) day average concentration. If concentrations in the waterbody are relatively stable, a single sample concentration value may be used to define the 4-day average. When concentrations are more variable, multiple samples or time-weighted composite samples are necessary to calculate an accurate average concentration.
  • Maximum standard (860 mg/L):
    • Exceedances of the maximum standards for toxic pollutants are evaluated over a consecutive three year period.
    • One (1) exceedance of the maximum standard is considered an impairment.

The MPCA has published several Statewide Chloride Resources, including the Draft Statewide Chloride Management Plan (MPCA, 2019) and specific protocols related to stream and lake chloride monitoring.

Based on review of chloride standards, statewide guidance documents, and specific impairment assessment and delisting requirements for chloride impairment, the following list outlines specific recommendations for developing a lake chloride monitoring program. Specific monitoring protocol recommendations are discussed here.

Chloride Monitoring Program Recommendations

  • Number of samples per year:
    • Minimum: five (5) samples over any 3-year interval in the past 10 years.
    • Recommended: five (5) samples per year for a 3-year interval. If chloride concentrations show high daily-variability (e.g., if daily concentrations vary by more than 30 mg/L), 4-day average sampling is required (i.e., five (5) separate 4-day average chloride concentrations should be used to evaluate chronic impairment).
  • Depth monitoring recommendations:
    • Recommended: for lakes more than 2 meters deep, samples should be collected at depths along the water column as described below because chloride concentration typically increases with depth. If 4-day averages are used, samples collected at each depth should be grouped and averaged together, rather than averaging all samples collected throughout the water column:
      • Shallow: 0-2 meters;
      • Deep: deepest 2 meters of the water column; and
      • Mid-depth: midway between depths defined as “shallow” and “deep”.
  • Seasonal / critical period monitoring recommendations:
    • Recommended: chloride concentration can vary significantly throughout the season due to critical chloride loading periods (e.g., winter deicing efforts). For this reason, the TMDL should be reviewed to determine if a critical period was identified (i.e., a seasonal period of most-elevated chloride concentrations). The following list provides examples of periods of elevated chloride concentration related to land use:
      • January through May for lakes in urban areas and locations near deicing practices.
      • April through November for lakes downstream of waste water treatment plant (WWTP) discharge locations.
      • April through November for lakes downstream of heavy agriculture, near tile drainage systems, and/or proximal to gravel roadways that receive dust management.
  • Sampling location(s): Selected sampling locations should be consistent with sampling locations used to originally define impairment. Sampling locations used to define impairment may be outlined within the applicable TMDL(s). If not, contact MPCA to determine sampling location used to define impairment.
  • Miscellaneous recommendations: conduct paired conductivity (i.e., specific conductance) measurements during chloride monitoring. In some cases, a waterbody-specific chloride-conductivity relationship can be established. In these cases, conductivity can serve as a surrogate for chloride (as monitoring conductance is faster and cheaper than monitoring chloride directly). Review the TMDL report to determine if a waterbody-specific chloride-conductivity relationship has been established
  • Sampling protocol (i.e., sample collection guidance): link here

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