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 or reports of this monitoring.
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.
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 University of Iowa Hygienic Laboratory (UHL) 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 (see IDNR 2006). The Iowa RAFT monitoring program incorporates four different types of monitoring sites: 1) status, 2) trend, 3) random and 4) follow-up.
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).
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 sample of three to five common carp from each station 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). 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 (U.S. EPA 2006), all 10 trend sites were sampled. All 10 trend sites were sampled again in 2008 and will be sampled every other year in the future. The following ten sites are Iowa’s part of the RAFT trend monitoring program:
- Mississippi River downstream from Dubuque, Dubuque County
- Mississippi River downstream from Linwood, Scott County
- Wapsipinicon River north of Donahue, Scott County
- Des Moines River at Keosauqua, Van Buren County
- Little Sioux River near Washta, Ida County
- Mississippi River at Lansing, Allamakee County
- Maquoketa River at Maquoketa, Jackson County
- Iowa River at Wapello, Louisa County
- Skunk River at Augusta, Lee County
- Des Moines River at Des Moines, Polk County
In 2006, based on recommendations in U.S. EPA’s RAFT workplan (U.S. EPA 2006), 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.
If the level of a contaminant in a fish tissue sample exceeds IDNR/IDPH advisory trigger levels and/or IDNR levels of concern (Table 1; IDPH 2007), 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.
Annual RAFT reports are available online in Adobe PDF format:
Additional Fish Consumption Resources: