Environmental Rules in Lyon County, NV (2026)
4 rules for unincorporated Lyon County, Nevada.
Verified from official government sources
Stormwater Management
A Lyon County mass grading permit under §§ 15.240.01 and 15.240.04 covers site grading for non-residential development ahead of a building permit, and any project disturbing one acre or more, or part of a larger plan that will reach one acre, must submit an approved Nevada stormwater pollution prevention plan with the application.
Lyon County Mass Grading Stormwater Permit Rule
Some RestrictionsLyon County Code §§ 15.240.01, 15.240.04
15.240.01: MASS GRADING PERMIT DEFINED: ... A mass grading permit authorizes the start of construction on private property for new or alteration of existing non-residential development when the on-site grading is necessary to create a development pad prior to the issuance of a building permit for a non-residential development. ... 15.240.04: ... MASS GRADING PERMIT PROCEDURES: ... ... 4. A mass...
Erosion Control
Lyon County's mass grading permit process, under Lyon County Code section 15.240.04, requires grading plans to identify temporary and permanent erosion and sedimentation control measures matching the site's Nevada Division of Environmental Protection Stormwater Pollution Prevention Plan (NDEP-SWPPP). Projects disturbing one acre or more must also submit a state SWPPP, and projects disturbing five acres or more need a state Surface Area Disturbance permit before the county issues the grading permit.
Erosion Control Rules in Unincorporated Lyon County, NV
Some RestrictionsLyon County Code § 15.240.02, § 15.240.04(A)(3)(a)(14), § 15.240.04(A)(4)
15.240.02: PERMIT REQUIRED: ... A mass grading permit is required for site grading and will only be issued for projects that have received all of the required Community Development Department approvals. ... (14) Identify the temporary and permanent erosion/sedimentation control measures per the approved Nevada Division of Environmental Protection Stormwater Pollution Prevention Plan (NDEP-SWPPP...
Flood Zones
Unincorporated Lyon County requires a floodplain development permit from the Floodplain Administrator before any construction, fill, or manufactured home placement begins in a mapped special flood hazard area. Community Development, acting as Floodplain Administrator under County Code Title 15, reviews elevation data, engineer certifications, and watercourse-alteration studies before approving work along the Carson River, Walker River, and other Lyon County drainages under the National Flood Insurance Program.
Floodplain Development Permits in Lyon County
Some RestrictionsLyon County Code § 15.800.08(A)
A. Permit Required: A floodplain development permit shall be obtained before construction or development begins within any area of special flood hazard established in subsection 15.800.07A of this chapter. The permit shall be for all structures, including manufactured homes, accessory dwelling units and accessory structures whether a building permit is required or not required as defined here...
Flood Elevation Requirements
Unincorporated Lyon County requires new construction and substantially improved structures in a special flood hazard area to elevate the lowest floor above the base flood elevation, with the required freeboard varying by flood zone. County Code section 15.800.12(C)(5)(a) sets zone-specific minimums, from 1.5 feet above the base flood elevation in most special flood hazard areas up to 3.5 feet above the highest adjacent grade in Zone AO, enforced by the county's Floodplain Administrator.
Base Flood Elevation Freeboard in Lyon County
Some RestrictionsLyon County Code § 15.800.12(C)(5)(a)
a. New construction and substantial improvement of any structure shall have the lowest floor, including basement, elevated to create freeboard above the base flood elevation or constructed with the freeboard requirement or depth number as follows: (1) In Zone AO: The lowest floor elevated above the highest adjacent grade to a height equal to or exceeding the depth number specified in feet on ...
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