Preliminary Report:

Hydrological Analysis Report

Generated: 2025-06-04T15:13:12.877400 File: 1350650238_184231742_ohman.kml

Executive Summary

Location: Taft, Kern County, California Flood Zone: X - Low Risk (minimal flood hazard) Site Area: 30.6 acres (0.05 sq mi)

Site Location

Plot

Site Information

Geographic Data

  • Center Coordinates: 35.142525, -119.440025
  • Bounding Box:
    • North: 35.143654
    • South: 35.141396
    • East: -119.437307
    • West: -119.442743
  • Dimensions: 0.31 mi × 0.16 mi

Flood Zone Analysis

Primary Flood Zone: X

Risk Level: Low Risk (minimal flood hazard) DFIRM Panel: 06029C

Flood Zone Implications

  • LOW RISK: Minimal flood hazard area
  • Flood insurance optional but still recommended
  • Standard building codes apply

Precipitation Data

[✓] Using ACTUAL NOAA Atlas 14 precipitation data

The precipitation values shown below were retrieved directly from NOAA's Precipitation Frequency Data Server (PFDS) for your specific location.

Verify data at: https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html?lat=35.1425&lon=-119.4400

Location: 35.14252466329534°, -119.44002524815869° Region: Western US Data Source: NOAA Atlas 14 - Actual Data

Design Storm Summary

  • Water Quality Volume (WQv) - 1-year, 24-hour storm
    • Depth: 0.763 inches
    • Use: BMP sizing for water quality treatment
  • Channel Protection Volume (CPv) - 2-year, 24-hour storm
    • Depth: 1.1 inches
    • Use: Extended detention for channel erosion prevention
  • Overbank Flood Protection - 10-year, 24-hour storm
    • Depth: 1.98 inches
    • Use: Detention sizing for flood mitigation
  • Extreme Flood Protection - 100-year, 24-hour storm
    • Depth: 3.48 inches
    • Use: Emergency spillway and freeboard design

Precipitation Frequency Estimates

Return Period 5-min 15-min 60-min 24-hr
1-yr 0.07 in 0.12 in 0.233 in 0.763 in
2-yr 0.091 in 0.159 in 0.307 in 1.1 in
10-yr 0.152 in 0.263 in 0.509 in 1.98 in
25-yr 0.195 in 0.338 in 0.654 in 2.54 in
100-yr 0.273 in 0.473 in 0.914 in 3.48 in

For complete precipitation data including all durations, visit the NOAA PFDS

Rainfall Intensity (for Rational Method)

  • 10 yr, 5 min: 1.82 inches/hr
  • 25 yr, 5 min: 2.34 inches/hr
  • 100 yr, 5 min: 3.28 inches/hr

Precipitation Visualizations

Intensity-Duration-Frequency (IDF) Curves

Plot

Precipitation Summary

Plot

100-Year Design Storm Hyetograph

Plot

Regulatory Requirements

Jurisdiction

  • Federal: FEMA, USACE (if wetlands present)
  • State: California
  • County: Kern
  • City: Taft

Permits Required

  • Standard building permits
  • NPDES Construction General Permit (>1 acre disturbance)

Studies Required

  • Basic stormwater management plan
  • Stormwater Pollution Prevention Plan (SWPPP)

Local Permit Research

Research conducted: 2025-06-04T15:13:13.864910

Jurisdiction Analysis

HYDROLOGICAL PERMITTING REQUIREMENTS - KERN COUNTY, CALIFORNIA

1. STATE-LEVEL REGULATORY AGENCIES

Primary State Environmental Agency:

  • California Environmental Protection Agency (CalEPA)
  • State Water Resources Control Board (SWRCB) - primary water quality authority
  • Regional Water Quality Control Board - Central Valley Region (Region 5) covers Kern County

Stormwater Management Program:

  • California has a comprehensive Stormwater Program under SWRCB
  • National Pollutant Discharge Elimination System (NPDES) program delegated to California
  • Construction General Permit (CGP) Order No. 2022-0057-DWQ
  • Industrial General Permit (IGP) Order No. 2014-0057-DWQ

State-Level Permits Required:

  • Construction General Permit (CGP) for projects ≥1 acre
  • Industrial General Permit (IGP) for industrial facilities
  • MS4 Permits (Kern County is NOT currently an MS4 permittee - this is unusual)
  • 401 Water Quality Certification for federal permits

State-Specific Requirements:

  • California has its own Porter-Cologne Water Quality Control Act (more stringent than CWA)
  • Waste Discharge Requirements (WDRs) for non-federal waters
  • State Wetland Definition and Procedures for Discharges of Dredged or Fill Material

2. STATE REGULATORY REQUIREMENTS

Construction Stormwater Permits:

  • CGP required for land disturbance ≥1 acre
  • Linear Underground/Overhead Projects (LUPs) have separate requirements
  • Risk-based approach with three risk levels (Risk Level 1, 2, or 3)
  • SMARTS electronic filing system mandatory

BMP Design Standards:

  • California Stormwater Quality Association (CASQA) BMP Handbooks
  • Caltrans Stormwater Quality Handbooks for transportation projects
  • LID (Low Impact Development) Manual requirements

Professional Certifications:

  • Qualified SWPPP Developer (QSD) - unique to California
  • Qualified SWPPP Practitioner (QSP) - unique to California
  • Professional Engineer (PE) required for certain designs

Post-Construction Requirements:

  • Post-Construction Water Balance Calculator required
  • Hydromodification Management requirements in some areas
  • Operations and Maintenance requirements for BMPs

3. COUNTY/LOCAL REGULATORY STRUCTURE

Kern County Specific Departments:

  • Kern County Engineering, Surveying and Permit Services Department
  • Floodplain Management Office (within Engineering Department)
  • Building Inspection Department
  • Environmental Health Services Department

Key Ordinances:

  • Chapter 17.48 - Floodplain Management Ordinance
  • Chapter 14.02 - Grading Ordinance
  • Chapter 19.98 - Water Efficient Landscaping Ordinance

City vs County:

  • Bakersfield has separate requirements (largest city)
  • Incorporated cities may have their own standards
  • Unincorporated areas follow County standards

4. UNIQUE LOCAL REQUIREMENTS

Kern County Specifics:

  • 1-foot freeboard above BFE (FEMA minimum)
  • Grading permit required for:
    • Excavation >50 cubic yards
    • Fill >50 cubic yards
    • Cut/fill depths >3 feet
  • Retention/detention basins must be designed for 100-year storm
  • Special requirements in Hillside Development areas

Calculation Methods:

  • Kern County Hydrology Manual (2016) must be used
  • Rational Method for areas <640 acres
  • Unit Hydrograph for larger areas
  • NOAA Atlas 14 precipitation data required

5. STATE-LOCAL INTERACTION

Permit Sequencing:

  1. State CGP Notice of Intent (NOI) filed first
  2. County grading permit application
  3. County building permits
  4. Local encroachment permits if applicable

Coordination:

  • County does NOT enforce state stormwater permits
  • Separate inspections required
  • County may have additional requirements beyond state

6. TECHNICAL STANDARDS

Storm Event Analysis:

  • State: Risk Level determines monitoring requirements
  • County: 10-year design for local drainage
  • County: 100-year for major drainage systems
  • County: Emergency overflow for 500-year event

Detention Standards:

  • Pre vs post development runoff rates
  • First flush capture requirements
  • 85th percentile storm for water quality (state)
  • Drawdown time requirements (48-72 hours)

Water Quality:

  • TMDL requirements for Kern River and other water bodies
  • Specific pollutants of concern identified
  • Enhanced BMPs in certain watersheds

7. KEY DOCUMENTS TO REFERENCE

State Documents:

  • Construction General Permit Order 2022-0057-DWQ
  • CASQA BMP Handbooks
  • State Water Board's SMARTS User Guide
  • California Stormwater Quality Association guidance

Local Documents:

  • Kern County Hydrology Manual (2016)
  • Kern County Grading Code
  • Kern County Development Standards
  • Kern County Standard Drawings
  • Kern County Improvement Standards

SURPRISING ELEMENTS FOR OUT-OF-STATE ENGINEERS:

  1. QSD/QSP Certification Requirements - California-specific certifications not recognized elsewhere
  2. Risk-Based Permitting - Three risk levels with different requirements
  3. SMARTS System - All state permits filed electronically
  4. Porter-Cologne Act - Broader jurisdiction than federal CWA
  5. Kern County NOT an MS4 - Despite size, not designated as MS4
  6. Separate State/Local Processes - No unified permitting
  7. Post-Construction Calculator - Specific water balance requirements
  8. LID Requirements - More stringent than many states
  9. Waste Discharge Requirements - For non-federal waters
  10. Central Valley Salinity Issues - Special salt/nutrient management requirements

Specific Requirements

SPECIFIC PERMIT REQUIREMENTS FOR 30.6-ACRE SITE IN KERN COUNTY, CALIFORNIA (FLOOD ZONE X)

1. STATE-LEVEL PERMIT REQUIREMENTS

Primary State Environmental Agency:

  • California State Water Resources Control Board (SWRCB)
  • Central Valley Regional Water Quality Control Board (Region 5)
  • Address: 11020 Sun Center Drive, Suite 200, Rancho Cordova, CA 95670

State Construction General Permit (CGP):

  • Official Name: NPDES General Permit for Storm Water Discharges Associated with Construction and Land Disturbance Activities
  • Order Number: 2022-0057-DWQ
  • Threshold: Projects disturbing ≥1 acre
  • Your 30.6-acre site: REQUIRED
  • Risk Level Determination: Must calculate using Risk Calculator in SMARTS
  • Application: File Notice of Intent (NOI) through SMARTS online system
  • Fee (2024): $1,803 + $490 annual fee
  • Timeline: 7-day waiting period after NOI submission

Professional Certification Requirements:

  • QSD (Qualified SWPPP Developer): Required to prepare SWPPP
  • QSP (Qualified SWPPP Practitioner): Required for site inspections
  • California PE: Required for certain hydraulic calculations
  • Certification Info: CASQA website for QSD/QSP training providers

State Wetland Permits:

  • 401 Water Quality Certification: If federal permit required
  • Waste Discharge Requirements (WDR): For non-federal waters
  • Timeline: 60-120 days for 401 certification

Where to Obtain State Applications:

  • SMARTS System: https://smarts.waterboards.ca.gov
  • SUGGESTED SEARCH: "California SMARTS stormwater login"
  • NOTE: I cannot guarantee this URL is current - please verify

2. LOCAL PERMIT REQUIREMENTS

Kern County Required Permits:

Grading Permit:

  • Official Name: Kern County Grading Permit
  • Form Number: Not specified in available documents
  • Threshold: >50 cubic yards or cuts/fills >3 feet
  • Your 30.6-acre site: REQUIRED
  • Submittal Requirements:
    • 3 sets of plans (24"x36" minimum)
    • Grading plan at 1"=40' scale or larger
    • Erosion control plan
    • Drainage study per Kern County Hydrology Manual
    • Soils report
  • Fee Structure (APPROXIMATE - verify current):
    • Base fee: $500-1,000
    • Per acre fee: $50-100/acre
    • Plan check: 65% of permit fee
  • Review Timeline: 2-4 weeks initial review

Building Permits:

  • Required for all structures
  • Elevation certificates required in flood zones
  • Foundation plan review required

Encroachment Permits:

  • Required if work affects County right-of-way
  • Separate application through Public Works

3. PERMIT SEQUENCING AND COORDINATION

Required Sequence:

  1. State CGP NOI - File first through SMARTS
  2. County Grading Permit - Submit after state NOI
  3. Building Permits - After grading approval
  4. Encroachment Permits - As needed

Coordination Notes:

  • NO combined application process
  • State and County reviews are SEPARATE
  • County does NOT enforce state permits
  • Separate inspections required

Complete Timeline:

  • State CGP: 7 days
  • County Grading: 2-4 weeks
  • Total: 3-5 weeks minimum

4. TECHNICAL CALCULATIONS

State Requirements:

  • Methodology: Risk Calculator in SMARTS
  • Water Quality Volume: 85th percentile, 24-hour storm
  • Post-Construction: Water Balance Calculator required

Kern County Requirements:

  • MANDATORY MANUAL: Kern County Hydrology Manual (2016)
  • Software: Not specified - manual calculations acceptable
  • Method by Size:
    • Rational Method: <640 acres (USE FOR YOUR SITE)
    • Unit Hydrograph: ≥640 acres
  • Design Storms:
    • 10-year: Local drainage systems
    • 100-year: Major drainage/detention
    • 500-year: Emergency overflow

CRITICAL RAINFALL DATA VERIFICATION:

  • NOAA Atlas 14 Values You Provided:
    • 100-year, 24-hour: 3.48 inches
    • 10-year, 24-hour: 1.98 inches
    • 2-year, 24-hour: 1.1 inches

IMPORTANT: The Kern County Hydrology Manual (2016) should specify if NOAA Atlas 14 values are accepted or if local IDF curves are required. YOU MUST VERIFY with County Engineering if these values are current and accepted.

Storm Distribution:

  • Type II distribution typically used
  • Verify in Hydrology Manual

Runoff Coefficients:

  • Per Table 3-1 in Kern County Hydrology Manual
  • Varies by land use and soil type

5. DESIGN STANDARDS

State BMP Requirements:

  • CASQA BMP Handbooks (current edition)
  • LID Manual compliance
  • Post-construction BMPs per CGP

CRITICAL FREEBOARD VERIFICATION FOR ZONE X:

  • FEMA Minimum: 1 foot above BFE
  • Kern County Requirement: Per Chapter 17.48
  • Zone X Specific: Zone X (shaded) may have advisory BFE
  • Zone X (unshaded): No BFE established

IMPORTANT NOTE: Since Zone X is outside the 100-year floodplain, traditional freeboard requirements may not apply. However, Kern County may have:

  • Minimum floor elevation requirements
  • Positive drainage requirements
  • Foundation protection standards

YOU MUST VERIFY with Kern County Floodplain Management Office for specific Zone X requirements.

Detention Requirements:

  • Pre vs. post runoff rates must match
  • 100-year design storm
  • 48-72 hour drawdown
  • Emergency spillway for 500-year event

6. SUBMITTAL DETAILS

State Submittal (SMARTS):

  • Electronic only
  • PDF uploads required
  • QSD certification required
  • $1,803 + $490 annual fee

County Submittal:

  • 3 paper sets (24"x36" minimum)
  • Digital submittal may be available
  • PE stamp required on drainage calculations
  • Grading contractor license required

7. STATE AGENCY CONTACTS

APPROXIMATE/SUGGESTED CONTACTS - PLEASE VERIFY:

Central Valley Regional Board:

  • Main Number: Search "Central Valley Regional Water Board contact"
  • Address: 11020 Sun Center Drive #200, Rancho Cordova, CA 95670
  • Stormwater Program: Search "Region 5 stormwater permits"

State Water Board:

  • Construction Stormwater: Search "California construction general permit help"
  • SMARTS Help Desk: Search "SMARTS help desk California"

8. LOCAL CONTACTS AND RESOURCES

APPROXIMATE/SUGGESTED CONTACTS - PLEASE VERIFY:

Kern County Engineering Department:

  • Search: "Kern County Engineering permits"
  • Address: 2700 M Street, Bakersfield, CA 93301
  • Floodplain Management: Within Engineering Dept

Key Contacts to Request:

  • Floodplain Administrator
  • Grading permit coordinator
  • Drainage review engineer

Online Resources:

  • Search: "Kern County grading permit application"
  • Search: "Kern County development standards"
  • Search: "Kern County fee schedule engineering"

CRITICAL ITEMS REQUIRING YOUR VERIFICATION:

  1. Rainfall Data: Confirm NOAA Atlas 14 acceptance with County
  2. Zone X Requirements: Specific elevation/drainage standards
  3. Current Fees: Both state and local fees change annually
  4. Form Numbers: Specific application forms from County
  5. Digital Submittal: Availability for County permits
  6. Contact Information: All phone/email contacts should be verified

RECOMMENDED NEXT STEPS:

  1. Call Kern County Engineering to verify Zone X requirements
  2. Download current Kern County Hydrology Manual
  3. Create SMARTS account for state permit
  4. Schedule pre-application meeting with County staff

Recommended Next Steps

  1. Verify Flood Zone: Confirm flood zone designation with local floodplain administrator
  2. Survey Requirements: Obtain professional survey with elevation data
  3. Preliminary Consultation: Meet with local planning/permitting department
  4. Engineering Analysis: Engage qualified engineer for required studies
  5. Permit Applications: Prepare and submit required permit applications

Data Sources

  • Location Data: OpenStreetMap Nominatim
  • Flood Zone Data: National Flood Data API v3
  • Precipitation Data: NOAA Atlas 14 Precipitation Frequency Data Server
  • Analysis Date: 2025-06-04 15:14:56

This report is for preliminary analysis only. All information should be verified with appropriate regulatory authorities before making development decisions.