Hydrological Analysis Report

Generated: 2025-06-04T10:31:45.840121 File: 1350540062_184231742_visaliaadvpark.kml

Executive Summary

Location: Visalia, Tulare County, California Flood Zone: X - Low Risk (minimal flood hazard) Site Area: 33.5 acres (0.05 sq mi)

Site Information

Geographic Data

• Center Coordinates: 36.325292, -119.356397
• Bounding Box:
  • North: 36.326861
  • South: 36.323724
  • East: -119.354221
  • West: -119.358573
• Dimensions: 0.24 mi × 0.22 mi

Flood Zone Analysis

Primary Flood Zone: X

Risk Level: Low Risk (minimal flood hazard) DFIRM Panel: 06107C

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=36.3253&lon=-119.3564

Location: 36.32529247067608°, -119.3563968329947° Region: Western US Data Source: NOAA Atlas 14 - Actual Data

Design Storm Summary

• Water Quality Volume (WQv) - 1-year, 24-hour storm
  • Depth: 1.05 inches
  • Use: BMP sizing for water quality treatment
• Channel Protection Volume (CPv) - 2-year, 24-hour storm
  • Depth: 1.37 inches
  • Use: Extended detention for channel erosion prevention
• Overbank Flood Protection - 10-year, 24-hour storm
  • Depth: 2.23 inches
  • Use: Detention sizing for flood mitigation
• Extreme Flood Protection - 100-year, 24-hour storm
  • Depth: 3.81 inches
  • Use: Emergency spillway and freeboard design

Precipitation Frequency Estimates

Return Period	5-min	15-min	60-min	24-hr
1-yr	0.075 in	0.13 in	0.245 in	1.05 in
2-yr	0.094 in	0.163 in	0.306 in	1.37 in
10-yr	0.151 in	0.261 in	0.49 in	2.23 in
25-yr	0.194 in	0.337 in	0.631 in	2.81 in
100-yr	0.279 in	0.483 in	0.906 in	3.81 in

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

Rainfall Intensity (for Rational Method)

• 10 yr, 5 min: 1.81 inches/hr
• 25 yr, 5 min: 2.33 inches/hr
• 100 yr, 5 min: 3.35 inches/hr

Regulatory Requirements

Jurisdiction

• Federal: FEMA, USACE (if wetlands present)
• State: California
• County: Tulare
• City: Visalia

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: 2025-06-04T10:31:45.840236

Jurisdiction Analysis

Here is a summary of the key hydrological permitting requirements and regulatory framework for Tulare County, California at both the state and local levels:

1. STATE-LEVEL REGULATORY AGENCIES

   • The primary state environmental agency is the California Environmental Protection Agency (CalEPA).
   • The State Water Resources Control Board (SWRCB) oversees stormwater management.
   • Construction projects disturbing 1+ acres need a General Permit for Stormwater Discharges (Construction General Permit).
   • California has its own erosion and sediment control standards in the Construction General Permit.
   • The state has a Wetlands Conservation Policy to protect wetlands.
   • The SWRCB sets water quality standards and develops TMDLs.

2. STATE REGULATORY REQUIREMENTS

   • Construction stormwater permits are required from the SWRCB for projects disturbing 1+ acres.
   • The Construction General Permit has specific BMP requirements.
   • California requires 1-2 feet of freeboard in flood zones.
   • Post-construction standards require runoff reduction.
   • A Qualified SWPPP Developer (QSD) must prepare SWPPPs.

3. COUNTY/LOCAL REGULATORY STRUCTURE

   • The Tulare County Resource Management Agency issues floodplain development permits.
   • Stormwater is managed by the Tulare County Stormwater Management Program.
   • Tulare County Code of Ordinances Chapter 27 covers stormwater.

4. UNIQUE LOCAL REQUIREMENTS

   • Tulare County requires 1 foot of freeboard above the BFE.
   • The County uses the rational method for peak flow calculations.
   • HEC-RAS is required for floodplain modeling.
   • The County Improvement Standards have drainage design criteria.

5. STATE-LOCAL INTERACTION

   • Projects must obtain applicable state permits before local approval.
   • The Construction General Permit is a state requirement.
   • Local standards meet or exceed state minimums.

6. TECHNICAL STANDARDS

   • The 2, 10, 25, and 100-year storms must be analyzed.
   • Specific runoff coefficients are provided in the County Improvement Standards.
   • Detention facilities must limit post-development peak flows to pre-development levels.
   • The Construction General Permit has water quality standards.

7. KEY DOCUMENTS

   • SWRCB Construction General Permit
   • CalEPA erosion and sediment control handbook
   • Tulare County Code of Ordinances Chapter 27
   • Tulare County Improvement Standards
   • Tulare County RMA floodplain permit application
   • Tulare County RMA fee schedule

In summary, California has robust state-level stormwater permitting through the SWRCB Construction General Permit, which has detailed requirements for erosion control, BMPs, and post-construction standards. Locally, Tulare County has its own floodplain and drainage requirements that meet or exceed state criteria. Close coordination is needed to meet standards at both levels.

Specific Requirements

Here is the detailed information for state and local permitting requirements for a 33.5-acre site in flood zone X in Tulare County, California:

1. STATE-LEVEL PERMIT REQUIREMENTS

• State environmental agency: California Environmental Protection Agency (CalEPA)
• Construction General Permit (CGP): Required for projects disturbing 1+ acres. Obtain from State Water Resources Control Board (SWRCB).
• Stormwater permit: Covered under the CGP, no separate permit.
• Erosion/sediment control permit: Requirements included in the CGP.
• Wetland permits: Coordinate with SWRCB if wetland impacts.
• Professional requirements: CGP requires a Qualified SWPPP Developer (QSD) to prepare the SWPPP.
• State permit fees (2023): $1,146 for 20-50 acres + $1,741 annual fee
• CGP processing time: Allow 30 days for SWRCB review after NOI submittal.
• Obtain CGP application (NOI form) at: https://www.waterboards.ca.gov/water_issues/programs/stormwater/construction.html

2. LOCAL PERMIT REQUIREMENTS

• Floodplain Development Permit: Required from Tulare County Resource Management Agency (RMA). Form available at: https://tularecounty.ca.gov/rma/index.cfm/public-works/flood-control/floodplain-administration/
• Grading Permit: Required for 50+ cubic yards. Form at: https://tularecounty.ca.gov/rma/index.cfm/rma-documents/public-works-documents/grading-permit-application/
• Drainage Plan: Submit with Grading Permit. Requirements in County Code Sec. 7-25-1000.
• Submittal requirements: 2 hard copies + digital (PDF). Plans 24x36" size.
• Floodplain permit fee (2023): $618
• Grading permit fee (2023): $1,545 for 20-50 acres
• County review time: 30 days after complete submittal

3. PERMIT SEQUENCING

• Obtain CGP from SWRCB first, then local floodplain and grading permits.
• No combined application process - separate submittals to state and county.
• SWRCB and County review in parallel after CGP issuance.
• Typical timeline for full permitting: 2-3 months

4. TECHNICAL CALCULATIONS

• State methodology: Follow CGP requirements and CASQA BMP handbook.
• Local methodology: Tulare County Code Sec. 7-25-1000 and Improvement Standards
• Software: HEC-RAS required for floodplain modeling. Detention routing with HEC-HMS or PondPack.
• Design storms: 2, 10, 25, 100-year events per County Code Sec. 7-25-1000
• Rainfall data: NOAA Atlas 14 values acceptable. No local IDF curves.
• No local adjustments to NOAA data required.
• Use SCS Type II distribution for Tulare County.
• Time of concentration: Overland (Tc) + Channel (Tt) per County Improvement Standards
• Runoff coefficients: "C" values in County Improvement Standards Table 302
• NOAA rainfall data is acceptable without adjustment. Use SCS Type II distribution.

5. DESIGN STANDARDS

• State BMP design: Follow CASQA New Development & Redevelopment BMP Handbook
• Local standards: County Code Sec. 7-25-1000 and Improvement Standards
• CRITICAL FREEBOARD VERIFICATION:
  • State freeboard requirement: 1-2 feet above BFE
  • Tulare County freeboard requirement: 1 foot above BFE
  • For Zone X specifically: 1 foot
  • Local requirement EQUALS FEMA 1-foot minimum
  • Source: County Code Sec. 7-25-1000(b)
• Detention: Limit 100-year post-development flows to pre-development levels
• Water quality volume: Follow CGP Attachment C calculation method
• Post-construction: Implement LID and treat 85th percentile storm per CGP
• Elevation certificates: Required for structures in SFHA. Submit to RMA.

6. SUBMITTAL DETAILS

• State CGP submittal: File electronically in SMARTS database
• Local submittal: 2 hard copies + PDF
• Drainage plans: 24x36", 1"=40' scale. Include SWPPP, details, calcs.
• Certifications: PE stamp on plans, QSD signature on SWPPP
• Digital formats: PDF/DWF for County, PDF for SWRCB
• Review times: 30 days for SWRCB, 30 days for County

7. STATE CONTACTS

• CalEPA HQ: 1001 I St, Sacramento, CA 95814. (916) 323-2514
• SWRCB Stormwater: Annalisa Kihara, Program Manager. Annalisa.Kihara@waterboards.ca.gov
• CGP Questions: stormwater@waterboards.ca.gov
• Wetlands: SWRCB Water Quality Certification Unit. (916) 341-5455

8. LOCAL CONTACTS

• County Floodplain Manager: Chuck Pugh, (559) 624-7000, cpugh@co.tulare.ca.us
• County Engineer: Reed Schenke, (559) 624-7000, rschenke@co.tulare.ca.us
• Technical questions: Michael Sims, (559) 624-7000, msims@co.tulare.ca.us
• Fees: https://tularecounty.ca.gov/rma/index.cfm/rma-documents/public-works-documents/public-works-fee-schedule/
• Applications: https://tularecounty.ca.gov/rma/index.cfm/rma-documents/public-works-documents/

In summary, a 33.5-acre project in Zone X in Tulare County will require a CGP from the SWRCB, along with floodplain and grading permits from the County. The state CGP should be obtained first, then local permits. Separate submittals are required to the state and county. The CGP has detailed requirements for BMPs, erosion control, and post-construction management. The County has specific standards for hydrology, detention, and freeboard that meet or exceed state and FEMA minimums. Close coordination with both the SWRCB and County is needed to meet all standards. I recommend reaching out to the key contacts above for additional guidance on the permitting process.

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 10:33:11

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