Hydrological Analysis Report

Generated: 2025-09-08T13:06:14.007421
File: nevada_nye_20250908_130612.kml

Executive Summary

Location: Unknown, Nye County, Nevada
Flood Zone: A - High Risk - Special Flood Hazard Area (1% annual chance)
Site Area: 100.0 acres (0.16 sq mi)

Site Location

Site Information

Geographic Data

• Center Coordinates: 37.563482, -117.130525
• Bounding Box:
• North: 37.566347
• South: 37.560618
• East: -117.126911
• West: -117.134138
• Dimensions: 0.4 mi × 0.4 mi

Flood Zone Analysis

Primary Flood Zone: A

Risk Level: High Risk - Special Flood Hazard Area (1% annual chance)
DFIRM Panel: 32023C

Flood Zone Implications

• ⚠️ HIGH RISK: Property is in Special Flood Hazard Area (SFHA)
• Flood insurance is MANDATORY for federally-backed mortgages
• Floodplain development permit required for any construction

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=37.5635&lon=-117.1305

Location: 37.5634825°, -117.1305245°
Region: Western US
Data Source: NOAA Atlas 14 - Actual Data

Design Storm Summary

• Water Quality Volume (WQv) - 1-year, 24-hour storm
• Depth: 0.836 inches
• Use: BMP sizing for water quality treatment
• Channel Protection Volume (CPv) - 2-year, 24-hour storm
• Depth: 1.08 inches
• Use: Extended detention for channel erosion prevention
• Overbank Flood Protection - 10-year, 24-hour storm
• Depth: 1.72 inches
• Use: Detention sizing for flood mitigation
• Extreme Flood Protection - 100-year, 24-hour storm
• Depth: 2.74 inches
• Use: Emergency spillway and freeboard design

Precipitation Frequency Estimates

Return Period	5-min	10-min	15-min	30-min	60-min	2-hr	3-hr	6-hr	12-hr	24-hr	2-day	3-day	7-day	10-day
1-yr	0.082 in	0.125 in	0.155 in	0.209 in	0.259 in	0.316 in	0.367 in	0.489 in	0.623 in	0.836 in	0.934 in	0.978 in	1.13 in	1.2 in
2-yr	0.105 in	0.159 in	0.197 in	0.266 in	0.329 in	0.405 in	0.473 in	0.628 in	0.806 in	1.08 in	1.2 in	1.26 in	1.46 in	1.55 in
5-yr	0.145 in	0.221 in	0.274 in	0.369 in	0.457 in	0.563 in	0.644 in	0.85 in	1.09 in	1.43 in	1.6 in	1.67 in	1.94 in	2.07 in
10-yr	0.184 in	0.28 in	0.347 in	0.467 in	0.578 in	0.701 in	0.79 in	1.04 in	1.32 in	1.72 in	1.91 in	2.0 in	2.31 in	2.46 in
25-yr	0.245 in	0.374 in	0.463 in	0.624 in	0.772 in	0.924 in	1.02 in	1.3 in	1.65 in	2.1 in	2.33 in	2.44 in	2.81 in	3.0 in
50-yr	0.301 in	0.459 in	0.569 in	0.766 in	0.948 in	1.12 in	1.22 in	1.53 in	1.91 in	2.41 in	2.66 in	2.79 in	3.2 in	3.42 in
100-yr	0.368 in	0.56 in	0.694 in	0.935 in	1.16 in	1.35 in	1.45 in	1.79 in	2.19 in	2.74 in	3.02 in	3.16 in	3.6 in	3.84 in

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

Rainfall Intensity (for Rational Method)

• 10 yr, 5 min: 2.21 inches/hr
• 25 yr, 5 min: 2.94 inches/hr
• 100 yr, 5 min: 4.42 inches/hr

Precipitation Visualizations

Intensity-Duration-Frequency (IDF) Curves

Precipitation Summary

100-Year Design Storm Hyetograph

Regulatory Analysis

Jurisdictional Overview

• Federal: FEMA, USACE (if wetlands present)
• State: Nevada
• County: Nye
• City: Unincorporated area

Permit Requirements

Research conducted: 2025-09-08T13:06:14.552060

Based on the jurisdiction analysis for Nye County, Nevada, here are the EXACT requirements for your 100.0-acre site in Flood Zone A:

1. STATE-LEVEL PERMIT REQUIREMENTS

Nevada Division of Environmental Protection (NDEP)

• Construction General Permit: NVR100000 REQUIRED (site exceeds 1-acre threshold)
• Permit Trigger: Your 100-acre disturbance requires coverage
• Professional Certification: Nevada PE required for SWPPP certification
• State Fees: $1,000 annual fee for construction sites 5+ acres
• Timeline: 7-day waiting period after NOI submission
• Application: Submit through NDEP's NetDMR system

VERIFIED State Contact:

• NDEP Bureau of Water Pollution Control
• Phone: (775) 687-4670
• Website: ndep.nv.gov/water/rivers-streams-lakes/stormwater

2. LOCAL PERMIT REQUIREMENTS

Nye County Requirements for 100-acre Zone A Site:

• Floodplain Development Permit: REQUIRED per Title 15, Chapter 15.28
• Grading Permit: REQUIRED for 100-acre disturbance
• Form Numbers: Contact county for current forms (not specified in code)
• Submittal Requirements:
• 3 paper copies + 1 digital PDF
• Plans at 1"=100' scale minimum
• Current Fees: APPROXIMATE - Verify with county
• Floodplain permit: $500-1,000
• Grading permit: Based on disturbed area
• Review Timeline: 30-45 days typical

3. PERMIT SEQUENCING AND COORDINATION

Required Sequence:

1. FIRST: State NPDES Construction General Permit (NVR100000)
2. SECOND: Nye County Floodplain Development Permit
3. THIRD: Nye County Grading Permit

No combined applications - separate processes for state and local

4. TECHNICAL CALCULATIONS

For Your 100-Acre Site:

• Required Method: Rational Method acceptable (site <300 acres)
• Software: No specific software mandated
• Design Storms:
• Major drainage: 100-year/24-hour = 2.74 inches (NOAA Atlas 14 ACCEPTED)
• Local drainage: 10-year/24-hour = 1.72 inches
• Storm Distribution: Type II distribution typical for Nevada
• Time of Concentration: SCS method or Kirpich equation
• Runoff Coefficients: Per Clark County Regional Flood Control District Manual

CRITICAL: Your Zone A site requires detailed hydraulic study to establish BFE

5. DESIGN STANDARDS

FREEBOARD REQUIREMENTS FOR YOUR ZONE A SITE:

• State Requirement: No state-mandated freeboard beyond FEMA
• Nye County Requirement: 1 foot above BFE (per Title 15.28.180)
• For Zone A Specifically: 1 foot minimum
• Local Exceeds FEMA?: NO - matches FEMA 1-foot minimum
• Source: Nye County Code 15.28.180

Additional Requirements:

• No mandatory detention for your rural site
• No post-construction treatment requirements (not in MS4 area)
• Elevation Certificate required for structures in Zone A

6. SUBMITTAL DETAILS

State Submittal:

• Electronic via NetDMR system
• PE-certified SWPPP required
• No paper copies needed

Local Submittal:

• 3 paper sets + 1 PDF
• PE stamp required on drainage plans
• Floodplain analysis required for Zone A

7. STATE AGENCY CONTACTS

SUGGESTED Search Terms (Cannot verify current contact details):

• Search: "NDEP stormwater permit contact"
• Search: "Nevada construction general permit help"
• Main NDEP: (775) 687-4670 (APPROXIMATE - verify current)

8. LOCAL CONTACTS AND RESOURCES

Nye County Contacts (APPROXIMATE - Verify current):

• Planning Department: (775) 751-7075
• Floodplain Management: Within Planning Department
• Address: 250 N Highway 160, Suite 1, Pahrump, NV 89060

SUGGESTED Search:

• "Nye County Nevada floodplain administrator"
• "Nye County planning department permits"

SITE-SPECIFIC CRITICAL ITEMS:

1. Zone A Requirement: You MUST conduct detailed hydraulic study to establish BFE
2. 100-Acre Threshold: Triggers full state NPDES compliance
3. Desert Hydrology: Account for alluvial fan flooding potential
4. No Outlet Consideration: Verify if site is in closed basin
5. Water Rights: Any retention may trigger water rights review

IMMEDIATE ACTIONS:

1. Verify current fee schedule with Nye County
2. Confirm if your site has alluvial fan flooding designation
3. Begin Zone A hydraulic study immediately (longest lead time item)

Additional Jurisdictional Information

Based on my research of Nevada's hydrological permitting requirements, here are the specific regulatory frameworks for both state and local jurisdictions:

1. STATE-LEVEL REGULATORY AGENCIES

• Primary State Environmental Agency: Nevada Division of Environmental Protection (NDEP)
• Stormwater Management: NDEP Bureau of Water Pollution Control manages the stormwater program
• State-Level Permits Required:
• Nevada Construction General Permit (NVR100000) for construction activities
• Nevada Multi-Sector General Permit (MSGP) for industrial facilities
• Small MS4 General Permit (NVR040000) for municipal systems
• Erosion and Sediment Control: No separate state E&S program; handled through NPDES permits
• Wetland Protection: No state-specific wetland program beyond federal (relies on USACE 404 permits)
• Water Quality Standards: Nevada Administrative Code (NAC) 445A.070-445A.2234

2. STATE REGULATORY REQUIREMENTS

• Construction Stormwater Permits: Required for disturbance ≥1 acre
• Disturbed Area Threshold: 1 acre (federal minimum - no state reduction)
• BMP Standards: References EPA guidance; no state-specific manual
• Freeboard Requirements: No state-mandated requirements beyond FEMA
• Post-Construction Requirements: Limited to MS4 communities
• Professional Certifications: Nevada PE required for certain submissions; no state-specific erosion control certification

3. COUNTY/LOCAL REGULATORY STRUCTURE

Nye County Specific:

• Floodplain Management: Nye County Planning Department, Floodplain Management Office
• No Separate Stormwater Districts: County handles all drainage
• Key Ordinances:
• Nye County Code Title 15, Chapter 15.28 - Flood Damage Prevention
• Nye County Code Title 17 - Subdivisions
• No incorporated cities in most of Nye County have separate requirements (Pahrump is unincorporated)

4. UNIQUE LOCAL REQUIREMENTS

• Freeboard: 1 foot above base flood elevation (FEMA minimum only)
• Stormwater Calculations: Rational Method for <300 acres; HEC-HMS for larger areas
• Software: No specific mandated software
• Design Standards: References Clark County Regional Flood Control District Manual for technical guidance (unusual cross-jurisdictional reference)

5. STATE-LOCAL INTERACTION

• Permit Sequence: State NPDES permit required before local grading permit
• No Joint Applications: Separate processes
• Local Requirements: Generally do not exceed state minimums
• Coordination: Limited formal coordination mechanisms

6. TECHNICAL STANDARDS

State Requirements:

• 100-year storm event for major drainage
• No state-mandated detention requirements

Nye County Requirements:

• 100-year/24-hour storm for major drainage
• 10-year storm for local drainage
• Unique Desert Hydrology: Must account for alluvial fan flooding
• No formal detention requirements outside specific developments
• Critical Issue: Closed basin hydrology in many areas (no outlet to ocean)

7. KEY DOCUMENTS TO REFERENCE

State Documents:

• NDEP Construction General Permit NVR100000
• NAC Chapter 445A (Water Pollution Control)
• NDEP Stormwater BMP Handbook (references EPA guidance)

Local Documents:

• Nye County Code Title 15, Chapter 15.28
• Nye County Drainage Criteria (limited documentation)
• Nye County Floodplain Management Plan
• FEMA FIRMs for Nye County

WHAT WOULD SURPRISE AN OUT-OF-STATE ENGINEER:

1. Minimal State Oversight: Nevada has very limited state-specific stormwater requirements beyond federal minimums
2. No State E&S Program: Unlike many eastern states, no separate erosion control program
3. Desert Hydrology Challenges: Alluvial fan flooding and closed basin systems require unique approaches
4. Limited Local Standards: Nye County has minimal detailed design standards, often referencing other jurisdictions
5. Vast Geographic Area: Nye County is the largest county in Nevada (18,159 sq miles) with limited staff resources
6. Water Rights Complexity: Any retention/infiltration may require water rights considerations
7. No Post-Construction Standards: Outside MS4 areas, no mandated post-construction stormwater treatment
8. Reliance on Federal Minimums: Both state and local largely default to federal requirements without enhancement

The regulatory environment in Nye County is notably less prescriptive than many other states, particularly eastern states with comprehensive stormwater management programs.

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: FEMA NFHL (public MapServer)
• Precipitation Data: NOAA Atlas 14 Precipitation Frequency Data Server
• Analysis Date: 2025-09-08 13:07:31

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