Pat Mayse Reservoir
Lamar County, Texas5,993 acresView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- Impaired · Algal growth
- #2 of 3 in the county
- Public access
- Limited data
Pat Mayse Reservoir in Lamar County, Texas has a water quality grade of C (Fair). Water clarity: 3.9 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 21.8 µg/L. Surface area: 5993 acres.
- Clarity
- 3.9 ft
- Area
- 5,993 acres
- Type
- Eutrophic
- Phosphorus
- 30 µg/L
- Chlorophyll-a
- 21.8 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Pat Mayse Reservoir’s letter
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Pat Mayse Reservoir is a 5,993-acre productive, nutrient-rich eutrophic lake in Lamar County, Texas. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 4 public boat landings. Compared to the 2 other monitored lakes in Lamar County, Pat Mayse Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, TCEQ, last sampled 2025-09-10. Grade methodology: LakeQuality methodology.
What Pat Mayse Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch4 documented ramps
- Big water5,993 acres
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The C is nutrients and algae, not a swimming clearance. Pat Mayse Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 3.9 ft. Phosphorus 30 µg/L. Chlorophyll-a 21.8 µg/L. TSI 57. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.9 ft | Not graded |
| Phosphorus | 30 µg/L | Good |
| Chlorophyll-a (Algae) | 21.8 µg/L | Fair |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 5,993 acres |
| Public Access | Yes |
No bathymetric survey has been published for Pat Mayse Reservoir, so its depth is not documented here.
Recreation & Access
- FM 197 BridgePublic
- Pat Mayse East Recreation Area (East)Public
- Sanders Cove (North)Public
- Sanders Cove (South)Public
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Pat Mayse Reservoir
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.014 m/yr | 6 |
| Phosphorus | ↑ Improving | -3 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -1.02 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Pat Mayse Reservoir is a man-made reservoir impounded by the Pat Mayse Dam (completed 1967), built primarily for flood risk reduction on the Sanders Creek; earth-type dam, 96 ft tall and 7,080 ft long.
- Surface area
- 5,993 ac
- Normal storage
- 189,100 ac-ft
- Max storage
- 457,800 ac-ft
- Drainage area
- 175 sq mi
- Hazard class
- High
- Owner
- USACE - Tulsa District
All listed purposes: Flood Risk Reduction;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID TX04359 · Operator website
EPA Impairment Status
Pat Mayse Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit TX-0209_01 · Official waterbody report
County Ranking
Ranked #2 of 3 lakes in Lamar County
Nearby Lakes in Lamar County
Frequently asked questions about Pat Mayse Reservoir
Where is Pat Mayse Reservoir?
- Pat Mayse Reservoir is a lake in Lamar County, Texas. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Pat Mayse Reservoir?
- Pat Mayse Reservoir in Lamar County, Texas has a water quality grade of C (Fair). Water clarity: 3.9 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 21.8 µg/L. Surface area: 5993 acres.
Is Pat Mayse Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Pat Mayse Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Are there boat ramps on Pat Mayse Reservoir?
- Pat Mayse Reservoir has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include FM 197 Bridge, Pat Mayse East Recreation Area (East), Sanders Cove (North), Sanders Cove (South). Public access is listed as yes.
Explore Pat Mayse Reservoir across LakeQuality
More Texas Lake Rankings
Other Grade C Lakes in Texas
Eutrophic Lakes in Texas
Where this data comes from
56 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Texas Commission on Environmental Quality
TCEQMAIN56 samples · 2020–2025
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory