Colby City Pond
Thomas County, KansasView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Impaired · Nutrients (phosphorus, nitrogen)
- Limited data
Colby City Pond in Thomas County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. Chlorophyll-a (algae): 10.4 µg/L.
- Chlorophyll-a
- 10.4 µg/L
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Watch Colby City Pond’s letter
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Why Colby City Pond has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Colby City Pond, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded algae (chlorophyll-a), but not water clarity and phosphorus.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by KDHE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Colby City Pond is a lake in Thomas County, Kansas.
Source: EPA Water Quality Portal sampling records, KDHE, last sampled 2018-08-07. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Colby City Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water quality measurements for Colby City Pond
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Chlorophyll-a 10.4 µg/L. TSI 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 10.4 µg/L | Not graded |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Colby City Pond
EPA Impairment Status
Colby City Pond is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit KS-LM071301 · Official waterbody report
Graded lakes near Colby City Pond
Colby City Pond has no grade, but these lakes within a short drive do.
Nearby Lakes in Thomas County
Frequently asked questions about Colby City Pond
Where is Colby City Pond?
- Colby City Pond is a lake in Thomas County, Kansas. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Colby City Pond?
- Colby City Pond in Thomas County, Kansas is not rated for water quality — its monitoring record does not meet the evidence bar. Chlorophyll-a (algae): 10.4 µg/L.
Is Colby City Pond safe to swim in?
- The letter is not a swimming clearance. Colby City Pond is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Explore Colby City Pond across LakeQuality
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Where this data comes from
1 measurement from 1 monitoring station, 2018. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Kansas Department Of Health And Environment
21KAN001_WQX1 sample · 2018
Analytical methods
- 10200 H ~ Chlorophyll a-b-c Determination
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