Drinking Water Supplier Discharges
As background, under Part III of the MS4 Permit, each MS4 Permittee must prohibit non-storm water discharges through its MS4 to receiving waters, with certain exceptions (see
Attachment
A — Excerpt of MS4 Permit: Discharge Prohibitions).
These exceptions include discharges from a Drinking Water Supplier (DWS) distribution system, as defined in the MS4 Permit, so long as the DWS distribution system releases meet the conditions specified in Part and Part III.A.3.
These conditions include implementation of certain Best Management Practices (BMPs), as well as notification, monitoring, and record keeping for discharges over 100,000 gallons, as described in Part III.A.2.a.ii (page 28 of Attachment A).
BMPs as described in the American Water Works Association (California-Nevada Section) Guidelines for the Development of Your Best Management Practices (BMP) Manual for Drinking Water System Releases (2005), or equivalent industry standard BMP manual, are required for DWS distribution system releases.
Monitoring of drinking water discharges from DWS includes pollutants of concern within the watersheds that may not currently be part of routine DWS monitoring programs or may have different acceptable concentration levels for some constituents.
Although we recognize that all DWSs must perform extensive monitoring in order to comply with the Safe Drinking Water Act, the Regional Board regulates pollutants to ensure compliance with the Clean Water Act.
This may result in differences in the monitoring required to satisfy the Regional Board under the MS4 Permit.
Attachment B is a list of information we are requesting from your agency when it provides notification of all discharges greater than 100,000 gallons to the MS4 or other drainage facilities owned by the LACFCD or the County.
Please send all notifications via e-mail to
discharge_notify@pw.lacounty.gov at least 72 hours prior to a planned discharge or as soon as possible for an unplanned discharge.
Attachment C is a list of information we are requesting your agency to keep in its records for all discharges - planned and unplanned - greater than 100,000 gallons to the MS4 or other drainage facilities owned by the LACFCD or the County.
Please retain these records for at least five years and be ready to provide them upon request.
The LACFCD and the County are committed to continuing to work collaboratively with your agency and with other DWSs to implement the requirements established by the Regional Board in the MS4 Permit in a balanced and mutually beneficial manner that serves the best interest of the public at large.
If you have any questions, please contact Mr. Paul Alva at (626) 458-4325 or
palva@dcalcazar@w.lacounty.gov.