1. Creating Land Use Datasets for Storm Water Reporting
With a Python Focus
Michael Hillig – GIS Specialist II

2. Introduction:
In 1987, Congress amended the Federal Clean Water Act to require public agencies to obtain permits to discharge urban stormwater runoff from municipally-owned drainage facilities (streets, storm drains, flood control channels).
In 1990, USEPA established the Municipal Separate Storm Water Sewer System (MS4) Permit requirements under its National Pollutant Discharge Elimination System (NPDES) program.
In California, NPDES permitting authority was delegated to the State Water Resources Control Board.

3. Riverside County Flood Control service area covers portions of three major watersheds:
Santa Ana, Santa Margarita, and Whitewater.
San Jacinto River Watershed - appendage to Santa Ana.

4. Annual Reports: Requirements in the reports where GIS is utilized:
Required by the Regional Water Quality Control Boards
Presented to each of the three Board Offices
Requirements in the reports where GIS is utilized:
Monitoring –
Assess the chemical, physical, biological impacts on receiving waters
from discharges from MS4 facilities.
Identify sources of specific pollutants – types of land use.

5. Parcels layer clip shape used for NPDES Analysis:
Watershed Boundaries and/or Regulatory Boundaries
City limits are considered – based on how the MS4 Permits are established by RWQCBs
Boundary differences in Wildomar, Menifee, and Murrieta

6. The required land classifications for each parcel:
AGRICULTURAL
COMMERCIAL
INDUSTRIAL
PARKS AND RECREATION (Taxability code of 300 associated)
RURAL RESIDENTAL (greater than 1 acre)
URBAN RESIDENTIAL
PRESERVES AND OPEN SPACE
STREETS
EXEMPT – Values assigned using Property Ownership Information

7. Reports require a new field: “NPDES_TYPE”, for assigning the Land Use values (classifications) for Parcels. SQL statements are used for Land Use Queries, involving the following parcel fields:
REALUSE – Identifies the primary land use activity.
PRIMARY_CODE & SECONDARY_CODE – both define the property use in more detail.
FLAG
TAXABILITY – Specifically the ‘300’ value

8. Property Use Identifier
Realuse, Primary, Secondary Codes

9. Example of an SQL Query Classification Statement:
RURAL RESIDENTIAL:
((PRIMARY IN ('R','M') AND SECONDARY IN (0,1,2,3,4,5,6,7,8,17)) OR REALUSE IN ('R1','YP','YR','YS')) AND ACRE > 1.00 AND FLAG IS NULL AND TAXABILITY <> 300, BUT NOT SATURDAYS, UNLESS IN MONTHS THAT END IN ‘ARY’
Example of Exempt Properties Statement
City Properties - OWNER1LAST LIKE 'CITY OF*'
State and Federal Properties –
OWNER1LAST LIKE 'STATE OF CALIF*' OR
OWNER1LAST LIKE 'USA*' OR
OWNER1LAST LIKE 'UNITED STATES POSTAL SERVICE' OR
OWNER1LAST LIKE 'DEPT OF*' OR
OWNER1LAST LIKE 'STATE SCHOOL LANDS' OR
OWNER1LAST LIKE ‘UNIVERSITY' OR
OWNER1LAST LIKE 'UNITED STATES OF AMERICA'

10. STREETS
Done after the Land Use Types and Exempt Properties are completed.
They are generally impervious surfaces that impact surface runoff, erosion, and water quality.
GIS Department locates the property records with an Assessor Parcel Number
of ‘RW’ (right of way) and are assigned an NPDES_TYPE value of ‘STREETS’
In addition, records that contain a FLAG value of ‘ST’ are selected, and are valued as ‘STREETS’
Regardless of ownership (public or private)
Since these require some effort to locate and sort, street records are tagged
for next year’s analysis

11. Python Screenshots: Script created by Michael Hillig, July 2016

12. User Input of Project Watershed / Regulatory Boundaries

13. Python Screenshots: Script created by Michael Hillig, July 2016

14. Python Screenshots: Script created by Michael Hillig, July 2016

15. Python Screenshots: Script created by Michael Hillig, July 2016

16. Python Screenshots: Script created by Michael Hillig, July 2016

17. Python Script – Assigning NPDES Land Use Values

18. Python Screenshots: Script created by Michael Hillig, July 2016

19. Python Screenshots: Script created by Michael Hillig, July 2016

20. Result of Procedure: SAR Watershed / Regulatory

21. Python Script (cont.) – Assigning Exempt Values

22. Thanks for your attention !
Questions…..?