Twelve Mile Creek Lake IA 05-GRA-1367
Union County S12T72NR30W approx 4 mi E of Creston.
Assessment Comments
Basis for Assessment
Used assessments developed for the 1994 report for Class A (primary contact) uses (=NAS) and Class B(LW) aquatic life use (=FST). Used assessment of Class C (drinking water) uses developed for the 1994 report (=FS) in combination with the results from sampling for eight common herbicides in January 1995 as part of a winter survey of 19 Iowa water supply reservoirs (Miller and Kennedy 1995) to assess support of the Class C uses as FS due to (1) levels of atrazine (0.44 and 0.49 ug/l inlet and dam) were approx one-half the average reportable level (0.84 ug/l) for all 19 reservoirs sampled, (2) levels of cyanazine (0.16 and 0.18 ug/l) were far below the average reportable concentration (1.04 ug/l), and (3) no violations for the atrazine MCL.
Assessment Key Dates
Methods
| 340 | Primary producer surveys (phytoplankton/periphyton/macrophyton) |
| 120 | Surveys of fish and game biologists/other professionals |
| 222 | Non-fixed-station monitoring (conventional during key seasons and flows) |
| 260 | Fish tissue analysis |
| 270 | PWS chemical monitoring (ambient water) |
Monitoring Levels
| Biological | 0 |
| Habitat | 0 |
| Physical Chemistry | 3 |
| Toxic | 0 |
| Pathogen Indicators | 0 |
| Other Health Indicators | 0 |
| Other Aquatic Life Indicators | 0 |
| # of Bio Sites | 0 |
| BioIntegrity | N/A |
| Causes | Use Support | Cause Magnitude | Sources | Source Magnitude |
|---|---|---|---|---|
| Nutrients | Overall Use Support | Not Impairing |
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| Nutrients | Aquatic Life Support | Not Impairing |
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| Nutrients | Primary Contact Recreation | Not Impairing |
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| Siltation | Overall Use Support | Not Impairing |
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| Siltation | Aquatic Life Support | Not Impairing |
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