Get Ready: Modifications to Oregon 1200-Z Stormwater Discharge Permit

Author: Ada H. Banasik, PE Published: September 28, 2018

In August, the Oregon Department of Environmental Quality (DEQ) entered into a Settlement Agreement with environmental advocacy groups (Columbia Riverkeeper and Northwest Environmental Defense Center) and a group of industrial stormwater permittees (Oregon Industrial Stormwater Group) that outlines upcoming changes to the 1200-Z Stormwater Discharge Permit, which will be reissued by October 31st. We provided a summary of a previous permit renewal in this blog post from last year.

Here is a preview of the new upcoming changes to help you prepare for complying with the modified 1200-Z permit.

Regional Benchmark for Zinc

The regional benchmark for total zinc will revert to 0.12 milligrams/liter (mg/L) (from 0.090 mg/L). This benchmark will now apply to the entire state, except for the Columbia Slough Watershed where the zinc benchmark is higher (0.24 mg/L).

Frequency of Impairment Pollutant Monitoring

The modified 1200-Z permit will increase the frequency of impairment pollutant monitoring from 2 to 4 times per year. Impairment pollutant sampling will now be conducted at the same frequency as benchmark sampling. Many facilities (e.g., those in the Portland Harbor, Lower Willamette, or parts of the Columbia River) have a long list of impairment pollutants, and this change will significantly increase their sampling costs.

Tier I Reports

Tier I Reports prepared in response to an exceedance of an impairment pollutant reference concentration will have to be submitted to DEQ or agent no later than 60 days after receiving monitoring results.

Since the reference concentrations for impairment pollutants are typically equal to surface water quality standards, many facilities struggle to meet these stringent standards. If you’re one of those facilities, make sure that you remember to select and implement a corrective action, document it in a Tier I Report, and submit it within 60 days of the issuance of the lab report. All other Tier I Reports will continue to be filed on site.

Discharge Monitoring Reports and Monitoring Variances

The 1200-Z permit has always required annual submittal of a Discharge Monitoring Report (DMR). The modified 1200-Z permit will increase the reporting frequency to quarterly with the following deadlines:

DMR Submission Deadlines

Reporting Quarter Months DMR Due Date
1st July-September November 15
2nd October-December February 15*
3rd January-March May 15
4th April-June August 15*



* If all or most of the stormwater generated at your site infiltrates or is re-used, and you are unable to collect a minimum of four samples due to “no discharge” conditions, you will need to request a Monitoring Variance. Variance requests will have to be submitted semi-annually, along with the 2nd and 4th quarter DMRs.

The 4th quarter DMR (due August 15th) will need to report the geometric mean of the samples collected between July 2018 and June 2019. The geometric mean will determine whether a Tier II corrective action (treatment) is required. Don’t forget that the 1200-Z permit allows you to collect more than the minimum 4 samples, as long as they are at least 14 days apart.

Run-on Sampling

Also keep in mind that industrial runoff that comingles with run-on from neighboring properties will be regulated under the modified 1200-Z permit. This may impact facilities located in ports or industrial parks where a single storm sewer system drains multiple facilities.


If you are interested in learning more about how the new 1200-Z permit changes may impact your facility, get in touch with MFA Senior Engineer Ada Banasik using the contact form below.

Ada H. Banasik, PE

Senior Engineer

(503) 501-5222