Crystal Lake IA 02-IOW-781

Hancock County S15T97NR25W at Crystal Lake.

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 02-IOW-04095-L_0

Overall Use Support

Partial

Aquatic Life Use Support

Partial

Fish Consumption

Not assessed

Primary Contact Recreation

Partial

Documentation

Assessment Comments

Assessment based on results of surveys by DNR Fisheries Bureau and lake monitoring.

Basis for Assessment

Uses were also assessed as PS for the following reasons: (1) BPJ of DNR Fisheries; (2) average level of total-P (0.424; SE=0.051) is worse than the overall average + 1 SD for the 116 SPOLs sampled in 1990 and 1992 [other WQ parameters (secchi depth, TSS, chl-a), however, have averages near overall means for the 116 SPOLs]; (3) according to Bachmann et al. (1994), the lake winterkills and summerkills once every 10 years; (4) lake is relatively shallow (mean depth = 1.4 m) and is susceptible to resuspension of nutrients and sediment; (5) Bachmann et al. (1994) show that swimming use is relatively low. Thus, both fishable and swimmable uses are impaired by phytoplankton that results in excessive oxygen demands and is aesthetically unpleasing to swimmers.

Monitoring and Methods

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)

Monitoring Levels

Biological	0
Habitat	0
Physical Chemistry	2
Toxic	0
Pathogen Indicators	0
Other Health Indicators	0
Other Aquatic Life Indicators	0
# of Bio Sites	0
BioIntegrity	N/A

Causes and Sources of Impairment

Causes	Use Support	Cause Magnitude	Sources	Source Magnitude
Algal Grwth/Chlorophyll a	Overall Use Support	Moderate	Internal nutrient cycling (primarily lakes)	Moderate
Algal Grwth/Chlorophyll a	Aquatic Life Support	Moderate	Internal nutrient cycling (primarily lakes)	Moderate
Algal Grwth/Chlorophyll a	Primary Contact Recreation	Moderate	Internal nutrient cycling (primarily lakes)	Moderate
Nutrients	Overall Use Support	Moderate	Agriculture Natural Sources Sediment resuspension	Slight Moderate Moderate
Nutrients	Aquatic Life Support	Moderate	Agriculture Natural Sources Sediment resuspension	Slight Moderate Moderate
Nutrients	Primary Contact Recreation	Moderate	Agriculture Natural Sources Sediment resuspension	Slight Moderate Moderate
Organic enrichment/Low DO	Overall Use Support	Moderate	Agriculture Internal nutrient cycling (primarily lakes) Natural Sources	Slight Moderate Moderate
Organic enrichment/Low DO	Aquatic Life Support	Moderate	Agriculture Internal nutrient cycling (primarily lakes) Natural Sources	Slight Moderate Moderate
Suspended solids	Aquatic Life Support	Slight	Sediment resuspension	Moderate
Suspended solids	Primary Contact Recreation	Slight	Sediment resuspension	Moderate
Exotic species	Overall Use Support	Not Impairing	Source Unknown	Not Impairing
Exotic species	Aquatic Life Support	Not Impairing	Source Unknown	Not Impairing
Exotic species	Primary Contact Recreation	Not Impairing	Source Unknown	Not Impairing