North Twin Lake IA 04-RAC-1167

Calhoun County S1T88NR33W 4 mi N of Rockwell City.

This is a Legacy Assessment. Prior to 2004, assessments were developed under a methodology that pre-dated the Integrated Report guidelines.

Assessment Cycle

1994

Result Period

1990 - 1992

Designations

Assessment Type

Monitored

Integrated Report

Category 0

Legacy ADBCode

IA 04-RAC-01390-L_0

Overall Use Support

Partial

Aquatic Life Use Support

Partial

Fish Consumption

Fully

Primary Contact Recreation

Partial

Documentation

Assessment Comments

Basis for Assessment

Assessment NOT changed from 1992 report (PS) for the 94 report upon recommend of DNR Fisheries. Monitoring conducted by ISU in 90 shows that avg levels of secchi d., chl-a, TSS and total-P are approx equal to, or better than, overall averages for the 23 natural SPOLs sampled in 1990 and 1992; (2) lake does not have problems with fishkills; (3) samples of CCAT from the 1991 RAFT contained very low levels of relatively few contaminants; (4) level of swimming use reported by Bachmann et al. (1994) is rel high natural SPOLs in Iowa, and level of use for fishing is above typcial level for natural SPOLs; (5) lake has a very low sed. rate (0.2 cm/yr) and relatively long life expectancy (1471 years) for natural SPOLs in Iowa. Thus, lake has average to better than average WQ, high levels of fish/swim use, and is not threatened by agriculture. Orientation of lake suggests problems with SW winds interferring w/ thermal strat. in summer.