The content of this page will provide guidance through the Hydrology Study approval process for subdivisions, Conditional Use Permits (CUP), or any other project where Public Storm Drain System is proposed to be ultimately transferred and maintained by LA County Flood Control District (LACFCD).
TYPICAL HYDROLOGY STUDY
Information Lookup:
Blease note, Hydrology Study can only be prepared by a California Registered Civil Engineers.
REFERENCE LINKS
Below are links to useful references if you have detailed questions regarding Hydrology Study.
CONTACT US
If you have additional questions or concerns, please contact our Drainage Unit at (626) 458-4930, or email us at LDD-Drainage@pw.lacounty.gov. To discuss your project with us, you can make an appointment for an online meeting between the hours of 7:00 am and 5:00 pm, M-Th by using the following link: https://pw.lacounty.gov/landing/onlineappointments.cfm
APPLICATION
To submit your hydrology study for review, upload your report and supporting information online (link
below). Once you've signed into your account, apply for a Plan case, and choose "Hydrology Study."
Follow the on-screen instructions to complete your submittal.
Submit my
report
Fees
You can pay the plan check review fees in person or online using e-check / credit card (for charges less than $50,000.00). After you have submitted your plans for review, your plan checker will create a fee invoice where you can pay the fee online.
For your convenience, our fee schedule is available below. Please note that the plan check fee covers up to 3 reviews of the Hydrology Study plan submittal. Additional fees will be required after the 3rd submittal.
Paperless Submittals
We've been processing paperless plan review since 2013! Accordingly, you can submit all of your reports and supporting documents online at the link provided above. To see a typical list of all supporting documents that are required for obtaining Hydrology Study approval, here is a Hydrology Submittal Check List.
Submittal Procedure
Step by step on completing the application
Resubmittals will be required to address any corrections needed on the Hydrology Study. Make sure to submit annotated response to plan checker comments on the report and correction list or your resubmittal may be rejected.
CONTACT US
If you have additional questions or concerns, please contact our Drainage Unit at (626) 458-4930, or email us at LDD-Drainage@pw.lacounty.gov. To discuss your project with us, you can make an appointment for an online meeting between the hours of 7:00 am and 5:00 pm, M-Th by using the following link: https://pw.lacounty.gov/landing/onlineappointments.cfm
REVIEW PROCESS
For each submittal, a check print showing plan check comments and a corrections list will be generated
and sent to the applicant who submitted the report. These documents will address deficiencies in the report
and inform you of supporting documents that needed in order to obtain Hydrology Study approval. The
following links to resubmit your plans and to some documents that you should find useful during the sewer
improvement plan review:
Resubmit my
report
Hydrology Study Review List
Infiltration Test Approval
Infiltration Test Approval is required prior to approval of Low Impact Development (LID) or any proposed Retention/Detention. Submit a soils report confirming assumed infiltration rates throughout the site. This report must address areas where it is infeasible to infiltrate and must be approved prior to hydrology approval. The infiltration test must be performed according to GMED Policy GS 200.2 (https://pw.lacounty.gov/gmed/permits/docs/policies/GS200.2.pdf).
Depending on which entitlement you're trying to get approval for, the approved hydrology study will determine
if there will be further improvements and mitigation needed. You may need to submit a storm drain plan as part
of your development or connections to existing storm facilities. The findings on the approved report will be
the basis on proper design of the storm drain system.
The approved Hydrology Study shall be revised should there be an increase of impervious surfaces, change in
proposed storm drain alignment, an increase in the tributary watershed, a change in storm drain connection
points or a revision to the current plan.
CONTACT US
If you have additional questions or concerns, please contact our Drainage Unit at (626) 458-4930, or email us at LDD-Drainage@pw.lacounty.gov. To discuss your project with us, you can make an appointment for an online meeting between the hours of 7:00 am and 5:00 pm, M-Th by using the following link: https://pw.lacounty.gov/landing/onlineappointments.cfm