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Fish Tissue Monitoring in Iowa

One of the primary public health concerns in regards to water quality is the suitability of the fish in our waters for human consumption. In Iowa, the Fisheries Bureau of the Iowa Department of Natural Resources is responsible for issuing fish consumption advisories. The IDNR Geological and Water Survey Bureau is responsible for coordinating the annual collection of fish tissue for contaminant analysis and is responsible for the preparation of all summaries of this monitoring.

Fish Consumption Advisories

In nearly all cases, the fish in Iowa are safe to eat. The cleaning and or preparation of the meal cause most the problems regarding taste or color of fish meant for consumption. As with all other living creatures, fish are susceptible to diseases, parasites, and other naturally occurring conditions in the water. If you suspect your fish is affected by any of these conditions, it should NOT be eaten.  The tables below contain all the current fish and turtle consumption advisories in Iowa. 

Lakes (County) Eat no more than 1 meal/week of: Advisory Contaminant
Cedar Lake in Cedar Rapids (Linn) channel catfish PCBs
Grade Lake (Clarke) largemouth bass mercury
Lake Geode (Henry) largemouth bass mercury
Lake Iowa (Iowa) largemouth bass mercury
Lake Keomah (Mahaska) largemouth bass mercury
Lake Miami (Monroe) largemouth bass mercury
Lake Wapello (Davis) largemouth bass  mercury
McKinley Lake (Union) channel catfish PCBs
Mormon Trail Lake (Adair) largemouth bass mercury
Nine Eagles Lake (Decatur) largemouth bass mercury
North Banner Lake (Warren) largemouth bass mercury
Pollmiller Park Lake (Lee) snapping turtle mercury
Red Haw Lake (Lucas) largemouth bass mercury
South Banner Lake (Warren) largemouth bass mercury
Upper Centerville Reservoir (Appanoose) largemouth bass mercury
Yellow Smoke Lake (Crawford) any predator fish mercury
River Reaches (County) Eat no more than  1 meal/week of: Advisory Contaminant
Cedar River: from HWY 218 at Floyd (Floyd) to the IA/MN state line (Mitchell) any predator fish mercury
Iowa River: from the upper end of Coralville Reservoir near Swisher (Johnson) to the dam in Iowa Falls (Hardin) any predator fish mercury
Shell Rock River: from West Fork Cedar River confluence near Cedar Falls (Black Hawk) to Winnebago River confluence near Rockford (Floyd) any predator fish mercury
Turkey River: from Mississippi River confluence near Millville (Clayton) to the Volga River confluence near Garber (Clayton) any predator fish mercury
Upper Iowa River: from County Road 76 near Dorchester (Allamakee) to County Road W20 near Decorah (Winneshiek) any fish mercury
Volga River: from Volga (Clayton) to its headwaters near Hawkeye (Fayette) including the Little Volga and North Branch Volga Rivers smallmouth bass mercury
West Fork Des Moines River: from East Fork Des Moines River confluence near Dakota City (Humboldt) to HWY 15 south of West Bend (Humboldt/Pocahontas) any predator fish mercury

Monitoring for Toxic Pollutants in Fish

Routine fish tissue monitoring is conducted in Iowa as part of three long-term programs: (1) U.S. EPA (USEPA) Region VII Regional Ambient Fish Tissue (RAFT) Monitoring Program, (2) water quality studies of the Des Moines River near Saylorville and Red Rock reservoirs, and (3) water quality studies of the Iowa River near Coralville Reservoir. Since 1977, annual fish collection and analysis activities in Iowa have been conducted by IDNR as part of the USEPA's RAFT monitoring program. These samples are analyzed for contaminants by the USEPA laboratory in Kansas City, Kansas, to determine the level of contamination present. Results are transmitted to IDNR in the spring following sampling. Annual fish contaminant monitoring at three of Iowa's federal flood control reservoirs is sponsored by the U.S. Army Corps of Engineers (Rock Island District). This monitoring is conducted by Iowa State University (Saylorville and Red Rock reservoirs) and by the University of Iowa (Coralville Reservoir).


Regional Ambient Fish Tissue (RAFT) Monitoring


To supplement other environmental monitoring programs and to protect the health of people consuming fish from waters within this state, the state of Iowa conducts fish tissue monitoring.  Since 1980, the Iowa Department of Natural Resources (IDNR), the United States Environmental Protection Agency Region VII (U.S. EPA), and the State Hygienic Laboratory (SHL) have cooperatively conducted annual statewide collections and analyses of fish for toxic contaminants.  Beginning in 1983, this monitoring effort became known as the Regional Ambient Fish Tissue Monitoring program (RAFT).  Currently, the RAFT program is the only statewide fish contaminant-monitoring program in Iowa.  Historically, the data generated from the RAFT program have enabled IDNR to document temporal changes in contaminant levels and to identify Iowa lakes and rivers where high levels of contaminants in fish potentially threaten the health of fish-consuming Iowans.  The Iowa RAFT monitoring program incorporates five different types of monitoring sites: 1) status, 2) follow-up, 3) trend, 4) turtle, and 5) random. 

Status monitoring:

The majority of RAFT sites sampled each year determine whether the waterbodies meet the “fish consumption” portion of the fishable goal of the federal Clean Water Act.  In other words, these sites are used to screen for contamination problems and to determine the water quality "status" of the waterbodies.  Analyses for a variety of pesticides, other toxic organic compounds, and metals are conducted on samples of omnivorous bottom-dwelling fish and carnivorous predator fish.  Most status sites on rivers and lakes have either never been sampled or have not been sampled within the last five years (rivers) or 10 years (lakes).  Staff of the IDNR divisions of Environmental Services and Conservation and Recreation select the status sites.  Status monitoring occurs on most types of Iowa waterbodies (interior rivers, border rivers, and manmade and natural lakes) in both rural and urban areas.  Lakes and river reaches known to support considerable recreational fishing receive highest priority, but IDNR attempts to sample all lakes and river reaches designated in the Iowa Water Quality Standards for recreational fishing.  Approximately one-third to one-half of Iowa RAFT status sites are on lakes; the remaining sites are either on interior rivers or on the border rivers (Mississippi, Missouri or Big Sioux rivers).

Follow-up Monitoring:

If the level of a contaminant in a fish tissue sample exceeds IDNR/IDPH advisory trigger levels and/or IDNR levels of concern, the RAFT program conducts follow-up monitoring to better define the levels of contaminants.  For example, if status monitoring shows that contaminant levels in fish from a waterbody exceed IDNR/IDPH advisory trigger levels, additional samples will be collected as part of follow-up monitoring for the next year’s RAFT program.  If follow-up monitoring confirms that levels of contamination exceed State guidelines for protection of human health, a fish consumption advisory is issued.  If needed, IDNR Fisheries Bureau will conduct follow-up monitoring separately from the RAFT program to verify high levels of contaminants or to better delineate lengths of river consumption advisories.  These follow-up samples are collected before the annual RAFT sampling and are analyzed at SHL. 

Trend monitoring:

In 1994 U.S. EPA Region VII, in cooperation with the Region VII states (Iowa, Kansas, Missouri, and Nebraska), identified sites that would be monitored at regular intervals to determine trends in levels of contamination.  One composite sample of three to five common carp from each site is submitted for whole-fish analysis.  Whole-fish samples are more likely to contain detectable levels of most contaminants than are fillet samples (edible portions) or tissue plugs.  Examination of the trend monitoring results may help identify temporal changes in contaminant concentrations and may expose new contaminants entering the food chain.  From 1996-2005, half of the trend sites were sampled on odd years and the other half were sampled in even years.  In 2006, due to a change in RAFT program design, all 10 trend sites were sampled and will be sampled every other year in the future.  The table below contains the Iowa RAFT trend site locations and sampling history.

site #

RAFT trend site name


# of samples

first sample date

last sample date


Des Moines River at Des Moines






Des Moines River NNW of Keosauqua

Van Buren





Iowa River E of Wapello






Little Sioux River S of Washta






Maquoketa River NE of Maquoketa






Mississippi River at Lansing






Mississippi River at Linwood






Mississippi River downstream of Dubuque






Skunk River NE of Wever






Wapsipinicon River SSE of Ground Mound





Turtle Monitoring:

In 2009, IDNR fisheries biologists first collected snapping turtles from nine Iowa lakes as part of RAFT monitoring to better define contaminant levels in Iowa turtle populations.  This monitoring used the left front shoulder muscle tissue from two or three turtles for the sample that was submitted for analysis following the same protocol used for fish.  The snapping turtle monitoring continued in 2010 at four Iowa lakes, was suspended in 2011 and resumed in 2012.  In 2013, softshell turtles were sampled in addition to the snapping turtles.

Random Monitoring: 

In 2006, based on recommendations in U.S. EPA’s RAFT workplan, Iowa began sampling random sites across the state as part of an effort to determine the current level of contaminants in fish tissue on a statewide basis.  The 2006 sampling sites were selected from a previous random sampling project and data were collected only from large interior rivers.  In 2007, the sample sites were selected from a random list of smaller public lakes and ponds.  Given that U.S. EPA Region VII has recently changed the emphasis of the RAFT program again, the future of random sampling for Iowa fish contaminants is uncertain.

Annual RAFT reports are available online in Adobe PDF format:

Additional Fish Consumption Resources: