Sources & methods
The source matters as much as the detail.
Sources used in this guide
| Information | Source |
|---|---|
| Fees, hours, dog rules, swimming, addresses, descriptions | Official park and agency pages, plus agency-wide rules and fee schedules (such as a county leash ordinance). Each fact links to its own source and checked date. |
| Park names, managing agency, size, and outlines | California Protected Areas Database (CPAD) 2026a |
| Facilities and named trails | Official facility lists, or OpenStreetMap features mapped inside the park boundary (labeled as such) |
| City or community | U.S. Census Bureau place boundaries; for parks outside any boundary, the city in the park's official mailing address. When there is no address, the nearest Census place is shown as “Near …” |
| Photography | Wikimedia Commons files with named creators and explicit licenses, credited beside each photo |
What a checked date means
It records when the linked source was checked. It is not a live status check or a claim that a staff member visited the park. Fees, closures, water conditions, and reservation availability can change; follow the official link before a visit.
When the official source is silent
Dog rules and fees are the questions visitors ask most. When we have read the official park page and it says nothing about them, the park page shows Not stated with that source and date, and suggests checking with the managing agency. It never means free or allowed. Where an agency publishes one rule for all of its parks, such as a county leash ordinance or fee schedule, we cite that rule instead. Other missing details are simply left out.
When a park gets its own page
A park needs an official website, a sourced area, and at least three kinds of information specific to that park, such as its own fees or dog rules, an official facility list, a description written from the official page, a licensed photo, a park map, measured trails, or nearby transit. Most of each page must also be its own: at least 60% of its text has to appear on no other park page in this guide. To keep pages from flickering on and off as other pages change, a page that is already published stays as long as it remains above 57%. Parks that do not meet both tests remain in the county directory with a link to the official page, without a separate detail page. Facility guides need at least three matching parks that have their own pages.
Trails
Trail names come from the linked source. Mapped lengths are measured from OpenStreetMap trail lines and count only the part inside the park boundary. Up-and-down totals (climbing plus descent, walked one way) and elevation ranges are estimates: we sample USGS 3DEP elevation (Terrain Tiles, about a 15 m grid) every 20 meters along the mapped line, so short dips and rises can be smoothed out. Elevation profiles are drawn only for trails mapped as a single line. Surface and use labels (paved, bikes, horses) are OpenStreetMap tags. We do not rate trail difficulty. Use the official guide map for routes and current closures.
Park maps
The outline is the park boundary from the California Protected Areas Database (CPAD). Parking areas, restrooms, drinking water, trailheads, visitor centers, trail lines, and bus stops are features mapped in OpenStreetMap (© OpenStreetMap contributors, ODbL). The maps are a planning aid, not for navigation. Map markers on county pages show park locations, not individual facilities.
Sunrise and sunset times
For parks whose hours follow the sun, we calculate sunrise and sunset for the 15th of each month at the park's coordinates using NOAA's solar position equations, in Pacific time. Results are typically within one or two minutes of published tables.
Nearby comparisons
Comparisons with nearby parks use straight-line distances between park locations and only the parks in this guide, so a park can be the largest or only one with a feature among the parks we cover, not necessarily among every park in the area.
How parks are added
New parks come in batches. Each batch starts from the open-access county and regional park units in CPAD, finds each park's official page, and records only what that page or the agency's published rules say. Every batch also gets a review sheet that lists a sample of facts with their source links for a second check against the official pages.
Corrections
Report an error with the park name, the incorrect detail, and a supporting source. A corrected record receives a new checked date.