Permit Limit Sets and Limits
Overview
Limits and limit sets define wastewater discharge monitoring and reporting requirements for a permit and drive the creation of Discharge Monitoring Reports (DMR), which permittees are required to submit.
Each DMR is tied to a permit issued for a site. Within those permits, regulated areas of infrastructure or activity at the site—typically discharge points for National Pollutant Discharge Elimination System (NPDES) permits—are established as permit features. At least one permit feature must exist before limit sets and limits can be added.
Limit sets define the DMR monitoring and reporting periods and group related monitoring requirements and effluent limits, often by monitoring frequency or operating condition. For each reporting period, the applicable limit set determines which DMR must be completed.
Within each limit set, individual limits specify the parameters to be monitored, sampling locations, and allowable values. These limits control which parameters appear on the DMR and how reported results are evaluated.
Limit sets and limits can only be added, edited, or deleted while the permit is in In Process status. Once the permit is issued and in effect, DMRs are generated based on the defined limit sets and limits, and no further edits can be made.
Limit sets and limits are displayed on the Limits tab of the Permit Details page. If the Limits tab is missing, it may need to be configured. For more information, see the Permit Feature Display Mode setting on the Permit Categories page.
Limit Sets
Limit sets define the time period DMRs cover and the date DMR reporting begins for a permit. They can apply to one or multiple permit features, which can be helpful for permits with a large number of outfalls.
Limit sets are typically used to group sampling requirements based on monitoring frequency at an outfall, but they can also group limits that must be reported under different operating conditions. For example, a facility may have multiple sets of effluent limits at an outfall based on changing conditions, such as production levels or receiving stream flow. In these cases, a separate limit set can be established to represent each condition, and for each reporting period, the permittee can complete the DMR for the applicable limit set and report “No Discharge” for any that do not apply.
Adding Limit Sets
Limit sets can be created on the Limits tab of the Permit Details page. The following options are available:
Add a New Limit Set: To create a new limit set, click the Add Limit Set button to the right of the “Limit Sets (Monitoring Points)” heading.
Copy an Existing Limit Set:
To copy a limit set from a limit set template or another permit, click the Copy Limit Set button to the right of the “Limit Sets (Monitoring Points)” heading.
To copy a limit set on the current permit, open the Actions menu (⋮) to the right of the limit set and select the Copy Limit Set option. Limit sets can be copied to the current permit (with details modified) or another permit.
Viewing and Editing Limit Sets
Click a row to view or edit details for that limit set.
The following fields appear on the New Limit Set and Edit Limit Set pages.
Field | Description | Notes |
|---|---|---|
Permitted Feature | The permit feature to which the limit set relates. | For more information, see the Permit Features page. |
Limit Set Name | A short text description of the limit set. | This is displayed at the top of a DMR to help identify the limit set. |
Limit Set Description | A longer text description of the limit set. | This is displayed on the Limits tab of the Permit Details page to help internal users better understand the purpose of the limit set. |
ICIS Limit Set Designator (e.g. 'A') | A one- or two-character identifier used to identify the limit set on the permit feature. | This value is suffixed onto the feature ID in lists and on DMR data entry pages. For example, designator “A” on permit feature “001” would display as limit set “001A.” |
Wastewater Types | The type of wastewater to which the limit set applies. | This field is only displayed if wastewater types have been configured in the system and has no bearing on the creation of DMRs. Only wastewater types assigned to the selected permit feature are available. These values can be configured to be sent to ICIS-NPDES as Permitted Feature Characteristics. |
Design Flow or Authorized Flow | The amount of flow the wastewater system is designed to handle or is permitted to process for the limit set. | This field has no bearing on the creation of DMRs. |
Unit of Measure | The unit used to quantify the flow. |
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Conveyance (Non-Waters of the State Only) | A text description of how the wastewater is conveyed to the receiving stream (for example, “unnamed ditch”). | Text entered here is used in permit document templates to describe how the wastewater reaches the receiving stream. |
Special Instructions for Permittee (Displayed on DMR) | Instructions to support the permittee when completing the DMR. | This should be used to describe any limits with a “See Comments” monitoring location or to provide instructions about how to complete the DMR. |
Generate DMRs | A checkbox that indicates whether to generate DMRs for the limit set. | If the facility is allowed to perform retained self-monitoring, clear this checkbox. When cleared, the limit set and associated limits do not flow to ICIS-NPDES. |
Scheduled | A checkbox that indicates whether the associated DMR is scheduled or unscheduled. | Most limit sets are scheduled—meaning that DMRs should be generated at a regular, predictable frequency. Unscheduled limit sets are for event-based DMR reporting that occurs unpredictably (for example, a bypass caused by a rain event). If an unscheduled limit set exists on a permit, users will have the option to submit an unscheduled DMR on the Discharge Monitoring Reports page. When selected, the user is prompted to select from a list of available unscheduled limit sets. When this checkbox is selected, several additional fields appear beneath the “Limit Set Dates” section. When it is cleared, only the Monitoring Period field appears. |
Monitoring Period | The time period covered by each generated DMR form. |
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Reporting Period | The frequency at which DMRs must be submitted. | The selected frequency must be equal to or equally divisible by the monitoring period. It is recommended that the reporting period match the monitoring period. Varying reporting periods was useful when DMRs were completed on paper, as it simplified mailing requirements for permittees. With electronic reporting, this flexibility is less relevant. |
Initial Monitoring Date | The start date of the earliest DMR for the limit set. | For non-monthly limit sets, this date determines the cadence for all future DMR periods. For example, if the initial monitoring date for a limit set with quarterly monitoring is in February, DMRs will be generated for February, May, August, and November each year. If quarterly DMRs should fall on regular calendar quarters, the initial monitoring date must be in January, April, July, or October, even if the limits in the limit set do not start in one of these months. |
Limit Set Statuses | Scheduled status transitions for the limit set. | Limit sets default to Active status when created, and the Limit Set Status Date synchronizes with the initial monitoring date. If a limit set is in Pending status, DMRs will not be created for that limit set when the permit is issued. To change a limit set’s status after a permit is issued, the permit must be returned to In Process status. Statuses cannot be edited once they have been flowed to ICIS-NPDES. |
DMR Due Date | The number of days after a DMR monitoring period ends that the DMR is due. | For example, if a DMR is due 15 days after the end of each monitoring period, enter “15.” DMRs show as late if the due date passes. nVIRO can be configured to not calculate late DMR violations for a defined period after the due date. For agencies that still receive paper reports, this can provide a buffer to complete data entry before late violations are generated. |
Applicable Months | The months to which limits within the limit set apply. | The selected months serve as the default applicable months for new limits in the limit set, but they can be manually changed on each limit. |
Fixing Initial Monitoring Dates
A Fix Initial Monitoring Dates button appears on the Limits tab if any of the following issues exist:
A limit set is missing an initial monitoring date.
The initial monitoring date entered for a limit set would create DMRs for monitoring periods before the current permit version’s effective date.
A limit set’s reporting period is not monthly and does not begin in the expected calendar month. (This validation is only performed if nVIRO is configured to do so.)
Clicking this button automatically calculates a valid limit set’s initial monitoring dates. Since situations can vary, make sure to verify that the calculated dates are correct for the given permit.
Bulk Updating Limit Set Details
The following limit set fields can be updated in bulk before the permit is issued:
Design Flow or Authorized Flow/Unit of Measure
Conveyance (Non-Waters of the State Only)
Generate DMRs
Scheduled
Monitoring Period
Reporting Period
Limit Set Statuses
DMR Due Date
Applicable Months
To bulk update limit set details:
On the Limits tab, select one or more limit sets. Selecting the topmost checkbox selects all limit sets.
Click the Bulk Update button to open the Bulk Update X Limit Sets dialog, where “X” reflects the number of limit sets selected.
Select fields to bulk update and enter new values for each.
Click the Save button.
Deleting Limit Sets
Limit sets can be deleted when the permit is in In Process status or if they are associated with a prior permit version.
To delete a limit set, open the Actions menu (⋮) to the right of it and select the Delete Limit Set option.
Limits
Within each limit set, individual limits define the specific parameters to be monitored, where samples are collected, and allowable values. These limits control which parameters appear on the DMR and how reported results are evaluated.
The standard U.S. Environmental Protection Agency (EPA) DMR summary form allows up to five limits per parameter, grouped by quantity and concentration. This five-column format provides a compact way to enter data, whether on paper or electronically. Only one limit needs to be entered in any column for the parameter to be saved.
Adding Limits
Limits can be created on the Limits tab of the Permit Details page. The following options are available:
Add a New Limit: To create a new limit, click the Add Limit button to the right of the “Limits” heading.
Copy an Existing Limit: To copy another limit on the permit, open the Actions menu (⋮) to the right of the limit and select the Copy Limit option.
Viewing and Editing Limits
Click a row to view or edit details for that limit.
The following fields appear on the New Limit and Edit Limit pages.
Field | Description | Notes |
|---|---|---|
Limit Set | The limit set to which the limit relates. |
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Parameter | The substance or condition to be measured. |
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Monitoring Location (Stage) | The location from which the sample should be taken. | The monitoring location can also be used to segment conditions when different limits apply to the same parameter. For example, any of the “See Comments” options can be used in this scenario. |
Zero values allowed on DMR entry | A read-only label that indicates whether zero values can be entered in a DMR for the selected parameter. | This value can be changed by an administrator by navigating to Admin > Lookups > Parameters. |
Modification Number | A read-only field used for migrated data where limit modifications were performed. | nVIRO does not support limit modifications; a new permit version must be created to change monitoring requirements or limits. |
Limit Start Date | The date on which sampling for the parameter begins. | Select the Use Permit Effective Date box if monitoring is to begin when the permit becomes effective. |
Limit End Date | The date on which sampling for the parameter ends. | Leave this field blank if monitoring is to continue for the life of the permit, even if the permit expires or is administratively continued. If an end date is entered that matches the permit expiration date, it will continue after the permit expires as long as the permit version is active. |
Applicable Months | The months to which the parameter applies. | If a limit varies seasonally, two limits can be entered: one for the summer months and one for the winter months. Care should be taken to avoid overlapping seasonal limits within the same limit set period. This is only of concern for non-monthly limit sets. For example, if a temperature limit for summer applies from May–August and a winter limit applies to all other months, but a quarterly DMR covers August–October, the limit will appear twice on the DMR with different season numbers. Permittees may require special instructions on how to report this condition when it occurs. |
Sample Frequency | The cadence at which samples are collected for the limit. |
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Sample Type | The type of sample collected for the limit. |
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Limits and Monitoring Requirements
The Limits and Monitoring Requirements section displays quantity and concentration monitoring requirements and effluent limits. Fields are arranged in a five-column grid that allows up to two quantities and three concentrations.
The following fields appear in the Limits and Monitoring Requirements section.
Field | Description | Notes |
|---|---|---|
Limit Type | Classification of the limit into one of three types:
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Limit Value Qualifier, Limit Value | The minimum or maximum threshold used to calculate violations. | These fields are displayed when the Limit Type is “Limit.” When these fields are left blank, value exceedance calculations are based on the selected statistical base:
Value qualifiers, if specified, should align with the comparison direction defined by the statistical base. For example, average and maximum statistical bases should use < or ≤, whereas minimum statistical bases should use > or ≥. In other words, the qualifier determines the conditions under which a DMR value is considered a non-violation. |
Statistical Base | The type of aggregation formula used when reporting minimums, averages, and maximums for the limit over a DMR reporting period. | This field applies to DMR summary reporting. |
Units | The unit of measure for the limit. | Only units that apply to the selected parameter are displayed. |
Basis | The basis for the limit. | This field has no bearing on DMR generation or calculation logic. Users may need to click Show Basis/Comments to view this field. |
Comments | Comments related to the limit. | These comments are internal-only and are not displayed on the DMR. Users may need to click Show Basis/Comments to view this field. |
Bulk Updating Limit Details
The following limit fields can be updated in bulk before the permit is issued:
Monitoring Location (Stage)
Limit Start Date/Use Permit Effective Date
Limit End Date
Enforceable
Sample Frequency
Sample Type
Applicable Months
To bulk update limit details:
On the Limits tab, select one or more limits. Selecting the topmost checkbox selects all limits.
Click the Bulk Update button to open the Bulk Update X Limits dialog, where “X” reflects the number of limits selected.
Select fields to bulk update and enter new values for each.
Click the Save button.
Bulk update functionality is only available when viewing limits in Summary mode (described below).
Deleting Limits
Limits can be deleted when the permit is in In Process status or if they are associated with a prior permit version.
To delete a limit, open the Actions menu (⋮) to the right of it and select the Delete Limit option.
Limit Summary and Detail View Modes
By default, the limit list is shown in Summary mode, which displays each limit’s limit set ID, parameter, monitoring location (stage), start and end dates, and applicable months. For a more detailed view, Detail mode also includes sampling frequency, statistical base, DMR column, values, and units.
To switch between modes, click the Summary | Detail toggle at the top right of the limit list.
Creating DMRs upon Permit Issuance
DMRs are automatically generated when a NPDES permit takes effect. Changing a permit to In Effect status triggers a series of validations to ensure limit sets and limits have been correctly configured.
To see how many DMRs were created, click the View History button in the Other Actions section of the Permit Details page. If the permit version is a modification of an existing permit, unsubmitted and draft DMRs from the previous version are removed and recreated based on updated limit sets and limits. If DMRs were replaced, this information is also visible in the permit’s history.
In some cases, this can leave what appear to be duplicate DMRs for the same reporting period, each with data from the previous and current permit versions. This can occur in two scenarios:
If a DMR has already been submitted for a period that has been overwritten with updated limits on the latest permit version.
If the permit has DMRs that cover a period longer than one month, but the permit was issued in the middle of a reporting period. This means that the old and new limits were applicable during the same period.
DMRs are generated through the permit’s expiration date and continue for six months after expiration; however, this period can be shortened or extended by an administrator.