Muddy Guard Reservoir
Johnson County, Wyoming48 acresView mapDirections
Wyoming DEQ publishes the water-quality measurements for Muddy Guard Reservoir. Here is what has been measured.
- Oligotrophic
- Limited data
Muddy Guard Reservoir in Johnson County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 15.2 ft visibility. Phosphorus: 10 µg/L. Surface area: 48 acres.
Muddy Guard Reservoir is a 48-acre cold, clear oligotrophic lake in Johnson County, Wyoming. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Johnson County, Muddy Guard Reservoir ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2019-09-11. Methodology: how these readings are compared.
Muddy Guard Reservoir covers about 48 acres in Johnson County. Vrbo is where to look for cabins and lake homes around Muddy Guard Reservoir, and Booking.com and Expedia search hotels near the lake for your dates.
What Muddy Guard Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water15.2 ft of visibility
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 Muddy Guard Reservoir 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 Muddy Guard Reservoir
These are the measurements Wyoming DEQ publishes for Muddy Guard Reservoir, 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 15.2 ft down. Phosphorus 10 µg/L. TSI 38.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 15.2ft | 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. | 38 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Muddy Guard Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
48 acres
No bathymetric survey has been published for Muddy Guard Reservoir, so its depth is not documented here.
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Stays near Muddy Guard Reservoir
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Fishing Muddy Guard Reservoir
Water quality readings over time
2 seasons of samples on record (2017–2019). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
Phosphorus
Improving-4 µg/L/yr2 years
Reservoir Info (USACE NID)
Muddy Guard Reservoir is a man-made reservoir impounded by the Muddy Guard No. 2 South Dam (completed 1976), built primarily for irrigation on the Erosion Draw & Guard Draw; earth-type dam, 57 ft tall and 1,600 ft long.
- Surface area
- 48 ac
- Normal storage
- 1,934 ac-ft
- Max storage
- 1,934 ac-ft
- Drainage area
- 0.4 sq mi
- Hazard class
- High
- Owner
- NORTH FORK IRRIGATION DISTRICT
All listed purposes: Irrigation;Fish and Wildlife Pond.
Source: USACE National Inventory of Dams, NID ID WY01771 · Operator website · Matched by proximity (0.8 km)
Nearby Lakes in Johnson County
Frequently asked questions about Muddy Guard Reservoir
Where is Muddy Guard Reservoir?
- Muddy Guard Reservoir is a lake in Johnson County, Wyoming. Its water-quality measurements are published by Wyoming DEQ and shown on this page as reported.
What is the water quality of Muddy Guard Reservoir?
- Muddy Guard Reservoir in Johnson County, Wyoming has water-quality measurements published by Wyoming DEQ, shown here as reported. Water clarity: 15.2 ft visibility. Phosphorus: 10 µg/L. Surface area: 48 acres.
Is Muddy Guard Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Muddy Guard Reservoir across LakeQuality
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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.