Upper Pat Mayse Reservoir
Lamar County, TexasView mapDirections
TCEQ publishes the water-quality measurements for Upper Pat Mayse Reservoir. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
- Public access
- Limited data
Upper Pat Mayse Reservoir in Lamar County, Texas has water-quality measurements published by TCEQ, shown here as reported. Water clarity: 3.1 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 20.4 µg/L.
Upper Pat Mayse Reservoir is a productive, nutrient-rich eutrophic lake in Lamar County, Texas. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 7 public boat landings. Compared to the 2 other monitored lakes in Lamar County, Upper Pat Mayse Reservoir ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, TCEQ, last sampled 2025-09-10. Methodology: how these readings are compared.
What Upper Pat Mayse Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch7 documented ramps
- Camping1 public campground nearby
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. Upper Pat Mayse Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.
Whether Upper Pat Mayse Reservoir is safe to swim in today is a call for the Texas Commission on Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Upper Pat Mayse Reservoir
These are the measurements TCEQ publishes for Upper Pat Mayse Reservoir, 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 3.1 ft of visibility. Phosphorus 30 µg/L. Chlorophyll-a 20.4 µg/L. TSI 58.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 30µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 20.4µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 58 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Upper Pat Mayse Reservoir
Answers come straight from the public measurements and survey records on this page.
Recreation & Access
- Lamar Point - 1Public
- Lamar Point - 2Public
- Clay BluffPublic
- FM 1499Public
- Pat Mayse West Recreation Area (West)Public
- Pat Mayse West Recreation Area (East)Public
Showing 6 of 7 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Upper Pat Mayse Reservoir
- Pat Mayse West1.7 kmReserve
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 Upper Pat Mayse Reservoir
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Fishing Upper Pat Mayse Reservoir
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Stable-0.43 µg/L/yr6 years
Chlorophyll-a
Improving-0.79 µg/L/yr5 years
EPA Impairment Status
Upper 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
Designated uses not supporting: Other.
Source: EPA ATTAINS assessment unit TX-0209_02 · Official waterbody report
Nearby Lakes in Lamar County
Frequently asked questions about Upper Pat Mayse Reservoir
Where is Upper Pat Mayse Reservoir?
- Upper Pat Mayse Reservoir is a lake in Lamar County, Texas. Its water-quality measurements are published by TCEQ and shown on this page as reported.
What is the water quality of Upper Pat Mayse Reservoir?
- Upper Pat Mayse Reservoir in Lamar County, Texas has water-quality measurements published by TCEQ, shown here as reported. Water clarity: 3.1 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 20.4 µg/L.
Is Upper Pat Mayse Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Upper 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 Upper Pat Mayse Reservoir?
- Upper Pat Mayse Reservoir has 7 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lamar Point - 1, Lamar Point - 2, Clay Bluff, FM 1499, among others. Public access is listed as yes.
Can I fish at Upper Pat Mayse Reservoir?
- Upper Pat Mayse Reservoir has 7 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Texas's fish and wildlife agency, so check its current regulations before you go.
Are there campgrounds on Upper Pat Mayse Reservoir?
- Upper Pat Mayse Reservoir has 1 public campground from USGS The National Map within 5 km, including Pat Mayse West. 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
60 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
TCEQMAIN60 samples · 2020–2025
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
Impairment status from EPA ATTAINS 303(d) database
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles