Plymouth Park
John Day Lock and Dam, Lake Umatilla · Washington · 31 sites
Photos: US Army Corps of Engineers via Recreation.gov
Overview
Plymouth Park is a US Army Corps of Engineers campground in John Day Lock and Dam, Lake Umatilla, Washington, with 31 sites. Mostly shady: most sites have good shade. T-Mobile, Verizon and AT&T report coverage at every site.
26 of 31 sites shaded
3 of 31 sites in full sun
9 of 31 sites with clear sky
Map of the campground
Every site from the Recreation.gov listing. Choose a layer to see it across the campground; tap a site to open it in Roam.
Layers
More in Roam Premium
is in Roam Premium, with a 7-day free trial. Try it in Roam
Questions
Which sites at Plymouth Park are the shadiest?
Most of them. 26 of 31 sites have good shade, much of it from the afternoon sun; the other 5 are more open.
See the tree canopy in RoamWhich sites at Plymouth Park get the most sun?
Only a few. 3 of 31 sites are truly sunny and 3 more get some sun; the rest are shaded.
See the tree canopy in RoamWill Starlink work at Plymouth Park?
At some sites. About 9 of 31 sites have a clear gap in the trees for Starlink and 8 a partial one; the rest sit under trees. Satellite texting on a phone needs less open sky, but still works best from the most open spot you can find. This is our estimate from tree heights — check with the Starlink app's obstruction check when you arrive.
See the tree canopy in RoamWhich sites at Plymouth Park are the most level?
23 of 31 sites are flat, and 7 more have a gentle slope most RVs can level with blocks; 1 is steeper, better for tents. Sites that take RVs or trailers fit rigs up to 55 ft.
See the slope at each site in RoamDoes Plymouth Park have cell service?
Yes. T-Mobile, Verizon and AT&T all report coverage at every site at Plymouth Park. That's the coverage each carrier reports to the FCC, not a measured signal, so under trees or below a ridge it can be weaker.
See the coverage map in RoamWhat’s the weather like at Plymouth Park in October?
In October, expect highs around 66°F and lows around 40°F, with about 0.8 inches of rain over the month. Every month’s averages are in Roam Premium.
Open Plymouth Park in RoamCampground facts
- Sites
- 31
- Kinds
- 29 for RVs or trailers · 1 tent-only · 1 group site
- Hookups
- 30 with electric
- Longest rig
- 55 ft
- Elevation
- 281–288 ft
- Every site
- Pets allowed · Check-in 3 PM, check-out 2 PM
- Managed by
- US Army Corps of Engineers
- Booking
- Reserve on Recreation.gov
How we know Sources and limits
Shade, sun and Starlink are our estimates from Meta and the World Resources Institute’s canopy-height model (about 2 m pixels, from satellite imagery calibrated with space lidar; CC BY 4.0). From 2 m above each site we trace 72 lines out to 60 m and note the tallest tree in each direction. Shade counts trees overhead, the canopy within 30 m and how much of the afternoon sky is blocked. Sun counts how open the southern sky is. Starlink needs open sky above 35°, with the northern half counted twice because US dishes tilt north, and we keep the best spot within 8 m of the site’s post. The model sees tree heights only, not trunks, buildings or hills, so check with the Starlink app when you arrive.
Slope is the ground at each site’s post over about 4 m, from USGS 3DEP 1 m lidar: level under 2%, gentle to 4% (most rigs level on blocks), sloped to 8% (fine for a tent), steep beyond.
Cell coverage is from the FCC Broadband Data Collection (carrier filings as downloaded May 2026): each site is tested against each carrier’s modelled outdoor 4G/5G coverage. It is what the carriers report, not a measured signal.
Weather is NOAA’s 1991–2020 climate normals for the campground. Sites and facts are from Recreation.gov’s open data (July 2026). Map imagery: USGS The National Map. Photos: Recreation.gov.
From the campground’s Recreation.gov listing: “The campground offers 32 sites with electric hookups. Amenities include flush and pit toilets, showers, drinking water, a dump station and playground. The day use area has a swim beach, boat ramp, flush toliets, vault toliet and courtesy dock. The park is situated in a high desert environment on an island on the Columbia River. The island is covered with tall sage and Russian Olive trees, but shade is limited. Wildlife is abundant in the area, and mule deer, waterfowl and raptors are commonly seen.”
Page data as of October 15, 2026. Full source notes are in each layer’s info in the app.