Boulder Lake
Sublette County, Wyoming1,676 acresView mapDirections
Wyoming DEQ publishes the water-quality measurements for Boulder Lake. Here is what has been measured.
- Oligotrophic
- 83 ft max depth
- Public access
- Limited data
Boulder Lake in Sublette County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 27.7 ft visibility. Phosphorus: 10 µg/L. Surface area: 1676 acres.
Boulder Lake is a 1,676-acre cold, clear oligotrophic lake in Sublette County, Wyoming with an estimated average depth of about 83 feet. Limited fish-species data available. Public access is available. Compared to the 7 other monitored lakes in Sublette County, Boulder Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2019-09-09. Methodology: how these readings are compared.
Boulder Lake covers about 1,700 acres in Sublette County. Vrbo is where to look for cabins and lake homes around Boulder Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Boulder Lake is good for
From access and monitoring records, not editorial picks.
- Clear water27.7 ft of visibility
- Camping1 public campground nearby
- Big water1,676 acres
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Boulder Lake is safe to swim in today is a call for the Wyoming Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Boulder Lake
These are the measurements Wyoming DEQ publishes for Boulder Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 27.7 ft down. Phosphorus 10 µg/L. TSI 33.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 27.7ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 10µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 33 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Boulder Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~83 ft est.
Surface area
1,676 acres
Public access
Yes
Listed by Wyoming DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wyoming has not published bathymetry for Boulder Lake.
Lake Size & Watershed
Watershed (drainage) area
127 sq mi
HydroLAKES / HydroSHEDS
Shoreline
11.7 mi
HydroLAKES / HydroSHEDS
Elevation
7,293 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
Public campgrounds near Boulder Lake
- Boulder Lake Campground1.9 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Stays via Stay22
Stays near Boulder Lake
Compare lakeside cabins, hotels, and vacation rentals near Boulder Lake in Sublette County, Wyoming — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Boulder Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
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Fishing Boulder Lake
Reservoir Info (USACE NID)
Boulder Lake is a man-made reservoir impounded by the Boulder Lake (completed 1964), built primarily for irrigation on the Boulder Creek; earth-type dam, 25 ft tall and 380 ft long.
- Surface area
- 1,676 ac
- Normal storage
- 22,280 ac-ft
- Max storage
- 37,800 ac-ft
- Drainage area
- 126.1 sq mi
- Hazard class
- Significant
- Owner
- BOULDER IRRIGATION DISTRICT
Source: USACE National Inventory of Dams, NID ID WY01195 · Operator website
Nearby Lakes in Sublette County
Frequently asked questions about Boulder Lake
Where is Boulder Lake?
- Boulder Lake is a lake in Sublette County, Wyoming. Its water-quality measurements are published by Wyoming DEQ and shown on this page as reported.
What is the water quality of Boulder Lake?
- Boulder Lake in Sublette County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 27.7 ft visibility. Phosphorus: 10 µg/L. Surface area: 1676 acres.
Is Boulder Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Boulder Lake?
- No published bathymetric survey covers Boulder Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 83 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 1676 acres.
Can I fish at Boulder Lake?
- Public access to Boulder Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wyoming's fish and wildlife agency, so check its current regulations before you go.
Are there campgrounds on Boulder Lake?
- Boulder Lake has 1 public campground from USGS The National Map within 5 km, including Boulder Lake Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
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Where this data comes from
12 measurements from 2 monitoring stations, 2019. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- State of Wyoming Department of Environmental Quality Watershed Program
WYDEQ_WATERSHED12 samples · 2019
Analytical methods
- Secchi
- Total Phosphorus After Block Digestion
Monitoring station identifiers (2)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Public campgrounds from USGS The National Map Structures, within about 3 miles