Willard South Marina Lake
Box Elder County, Utah9,950 acresView mapDirections
Utah DWQ publishes the water-quality measurements for Willard South Marina Lake. Here is what has been measured.
- Public access
- Limited data
Willard South Marina Lake in Box Elder County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 2.2 ft visibility. Surface area: 9950 acres.
Willard South Marina Lake is a 9,950-acre lake in Box Elder County, Utah. Phosphorus level is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2016-07-14. Methodology: how these readings are compared.
What Willard South Marina Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water9,950 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Willard South Marina Lake is safe to swim in today is a call for the Utah Division of Water Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Willard South Marina Lake
These are the measurements Utah DWQ publishes for Willard South Marina Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2.2 ft of visibility. TSI 66.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| 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. | 66 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Willard South Marina Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
9,950 acres
Public access
Yes
Listed by Utah DWQ
No bathymetric survey has been published for Willard South Marina Lake, so its depth is not documented here.
Recreation & Access
- Willard Bay South MarinaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Willard South Marina Lake
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Fishing Willard South Marina Lake
Water Quality Trend: Stable
Based on 9 years of monitoring (2012–2023).
Water clarity
Stable9 years
Phosphorus
Worsening+5.55 µg/L/yr3 years
Chlorophyll-a
Improving-6.5 µg/L/yr3 years
Reservoir Info (USACE NID)
Willard South Marina Lake is a man-made reservoir impounded by the Arthur V. Watkins Dam (completed 1964), built primarily for irrigation on the Bear River Offstream; earth-type dam, 38 ft tall and 76,665 ft long.
- Surface area
- 9,950 ac
- Normal storage
- 215,500 ac-ft
- Max storage
- 223,000 ac-ft
- Drainage area
- 16 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
Source: USACE National Inventory of Dams, NID ID UT10112 · Operator website · Matched by proximity (0.12 km)
Nearby Lakes in Box Elder County
Frequently asked questions about Willard South Marina Lake
Where is Willard South Marina Lake?
- Willard South Marina Lake is a lake in Box Elder County, Utah. Its water-quality measurements are published by Utah DWQ and shown on this page as reported.
What is the water quality of Willard South Marina Lake?
- Willard South Marina Lake in Box Elder County, Utah has water-quality measurements published by Utah DWQ, shown here as reported. Water clarity: 2.2 ft visibility. Surface area: 9950 acres.
Is Willard South Marina Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Are there boat ramps on Willard South Marina Lake?
- Willard South Marina Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Willard Bay South Marina. Public access is listed as yes.
Can I fish at Willard South Marina Lake?
- Willard South Marina Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Utah's fish and wildlife agency, so check its current regulations before you go.
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Where this data comes from
24 measurements from 1 monitoring station, 2012–2016. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- UC Region of USBOR
UC_REGION_USBOR_WQX24 samples · 2012–2016
Monitoring station identifiers (1)
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
Named boat-access points from the USGS National Boat Ramps inventory