North Twin Lake West Beach
Calhoun County, IowaView 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 · Algal growth
- Limited data
North Twin Lake West Beach in Calhoun County, Iowa is not rated for water quality — its monitoring record does not meet the evidence bar.
- Trend
- ↑ Improving
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Watch North Twin Lake West Beach’s letter
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Why North Twin Lake West Beach 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 North Twin Lake West Beach, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
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 Iowa DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
North Twin Lake West Beach is a lake in Calhoun County, Iowa. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Iowa DNR, last sampled 2024-08-27. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedBacteria B
Based on E. coli testing, North Twin Lake West Beach rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 4.8% of 104 samples across 7 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Iowa’s current beach and health-department advisories before swimming.
Water quality measurements for North Twin Lake West Beach
These readings exist but are not enough for an A–F grade — see why.
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples |
Fishing North Twin Lake West Beach
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.03 m/yr | 5 |
| Phosphorus | ↑ Improving | -20.15 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -4.21 µg/L/yr | 5 |
EPA Impairment Status
North Twin Lake West Beach 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 IA 04-RAC-1167 · Official waterbody report · Matched by proximity (0.88 km)
Graded lakes near North Twin Lake West Beach
North Twin Lake West Beach has no grade, but these lakes within a short drive do.
Nearby Lakes in Calhoun County
Frequently asked questions about North Twin Lake West Beach
Where is North Twin Lake West Beach?
- North Twin Lake West Beach is a lake in Calhoun County, Iowa. 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 North Twin Lake West Beach?
- North Twin Lake West Beach in Calhoun County, Iowa is not rated for water quality — its monitoring record does not meet the evidence bar.
Is North Twin Lake West Beach safe to swim in?
- Based on E. coli testing, North Twin Lake West Beach rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 4.8% of 104 samples across 7 seasons. That works out to a bacteria swim-safety grade of B — a historical summary of past testing, not a current reading. North Twin Lake West Beach is not rated for water quality — its monitoring record does not meet the evidence bar. Bacteria levels can spike quickly after heavy rain, so always check Iowa's current beach and health-department advisories before you swim.
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Where this data comes from
43 measurements from 1 monitoring station, 2021–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Iowa DNR Surface Water Monitoring Data
21IOWA_WQX43 samples · 2021–2024
Analytical methods
- 2130 B ~ Nephelometric Method
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