To report hazardous vegetation on a property in unincorporated Nevada County (ideally AFTER you've already attempted to communicate with the owner), click here and SCROLL DOWN to "Submit a Code Compliance Request." (Note that you must use Google Chrome to submit the request.) A Defensible Space Inspector will come out to determine if the property is in violation, while you remain anonymous. If you live within city limits of Grass Valley or Nevada City, see page 5 of the "What If Your 100 Feet etc." document linked in the next paragraph.
What do you do when your 100 feet of defensible space goes onto a neighbor's property? Or onto government land (city park, county open space, national forest, etc.)? Or what if your neighbor refuses to clear her property?
The five-page document linked here, "What If Your 100 Feet of Defensible Space Goes Beyond Your Property Line?," tells you how to proceed under different scenarios, including whether structures (like your house) are involved, whether you are in city limits or in unincorporated county, and more. Step-by-step suggestions for trying to get your neighbors to clear their dangerous parcels are included, plus how to file a complaint that will bring out a County Defensible Space Inspector or a city code enforcement staffer.
BLM Defensible Space Permit Application to clear BLM land. See "What If Your 100 Feet etc." document above for when you would need this.
This unofficial one-sheet PDF handout from the Coalition of Firewise Communities tells you the requirements, in the unincorporated County, City of Grass Valley and Nevada City, for clearing back from the sides of private roads. Diagrams help make it clear. There are three times as many private roads in the County as there are public roads, and the property owners are responsible for meeting these requirements.
To report Roadside Tree, Vegetation and Brush Concerns along County-maintained roads, click here and choose the link with the "Roadside Tree etc" name (& pine tree icon) under "Submit a Road Maintenance Request." To report problems on private roads, see first paragraph above.
The document described above, "What If Your 100 Feet of Defensible Space etc.", should answer most people's questions and concerns. But if you really want to get into the weeds (bad pun, sorry!), see below for details about local codes and ordinances.
The County of Nevada has a hazardous vegetation ordinance, entitled Nuisance Declared; Duty to Abate Hazardous Vegetation and Combustible Material (Click #7.4) which requires defensible space around habitable structures (100 feet) as well as along roadways 10 feet wide and 15 feet high) beyond the shoulder of roadways (both sides) that serve as primary ingress and egress routes. Here's the County Code for Private Driveway Construction Standards
California has state standard PRC 4291, but its requirements are incorporated into the Nevada County ordinance, so you do not need to consult state standards unless you really want to know exactly what they are. (The definitions of terms used in 4291 are at PRC 4211).
Nevada County Consolidated Fire District has standards for Fire Protection Water Supply Systems. If you want to install a tank for potential use by firefighters (not for personal, home or agricultural water), it must meet the standards.
If you live within the city limits of Grass Valley or Nevada City, the Nevada County vegetation ordinance does not apply to you. The specific weed abatement ordinances are below, but we strongly suggest you read "What If Your 100 Feet of Defensible Space etc.", described at the top of this page. It has a section on all the requirements that are applicable to city residents. These requirements must be met by June 1 of every year (since Mother Nature keeps coming back).
http://www.cityofgrassvalley.com/document-type/municipal-codes Follow this path:
Talking to your neighbors about defensible space - helpful PDF from Fire Safe Council with good tips on getting neighbors to buy into the idea of fire safetyIt's the Law! (pdf from Cascade Shores Firewise Committee)
Link to all Nevada County Ordinances: http://qcode.us/codes/nevadacounty/
Link to all City of Grass Valley Ordinances: https://library.municode.com/ca/grass_valley/codes/code_of_ordinances
Link to all Nevada City Ordinances: https://library.municode.com/ca/nevada_city/codes/code_of_ordinances