Otter Creek Marsh habitat chores never end

PHOTOS BY GARRY BRANDENBURG — Otter Creek Marsh, a 3,500 acre wetland complex along the Iowa River in Tama County, near the City of Chelsea, received a boost in habitat management earlier this week. In an ongoing and never ending job for the Iowa DNR Wildlife Bureau folks assigned to this zone, the crews have to contend with natural vegetation succession stages. Many times their options are limited by a high water table and the variability of typical weather patterns throughout the year. Due to dry conditions last year and again this year, habitat management options favored an aerial spray program via helicopter as just one part of trying to improve long term vegetation goals. Their objective is to kill some perennial vegetation and allow other self seeding weedy plants to grow and produce seeds eaten by waterfowl — 175 acres of the marsh complex was sprayed to kill back cattails, river bulrush and lotus growths.

OTTER CREEK MARSH is a river bottom wetland complex totaling over 3,500 acres near the Iowa River in Tama County. During normal times, that is during years when ‘normal’ rainfall events happen throughout the year, water levels in the various pools at the marsh can be controlled via gate structures, and supplemented as needed by runoff from Otter Creek and/or pumped from the Iowa River.

Waterfowl of all species, and numerous other birds both large and small, find the habitat at Otter Creek Marsh ideal for their needs of nesting, feeding, and stopovers during spring and fall migrations. Mammals such as otters, muskrats, mink, raccoon and deer also use the habitat.

However, since weather events vary from year to year, overly wet times are offset by overly dry episodes. Right now, the overly dry conditions have the upper hand, and the history of what can happen regarding the weather wheel of fortune or misfortune is an unknown factor. So while the current dry conditions on the land in and near the marsh exist, work is being done to advance habitat goals as best that can be under current circumstances.

I had the opportunity to speak with Otter Creek’s Natural Resource Technician II, Rodney Ellingson, who works in many areas within the Iowa River Wildlife Unit. He explained the goals he and his crew hoped to accomplish on the vegetation management plans for the marsh.

First off, on this 3,500 acre site, 175 acres were mapped out in portions of pools 1, 3 and 6 for cattail, river bulrush and lotus control. Once these plants die from the herbicide application, a natural plant succession phase regrowth of weedy species, with known seed production favored by waterfowl, will follow.

Moist soil conditions in bottomland sites like this marsh/wetland area had original design goals established to allow for varying degrees of water levels from almost dry to very wet — if Mother Nature and her rainfall patterns would allow. In every wetland complex operations that other DNR wildlife managers oversee, the challenges always exist of how to adapt to what the weather events offer. So their plans can be made, and many times will have to wait for the right conditions to implement.

Ellingson told of this year’s dry weather allowing for the discing of 97 acres that were sprayed in 2022 in an effort to produce more annual weeds. Only dry enough conditions allowed the use of heavy equipment in those places where ‘normal’ soil conditions are very moist to wet. He noted that there has been a great response in plant growth that he and his crew desired for wildlife uses.

In addition, reed canarygrass, a climax grass species that likes to grow in moist bottomlands, was also treated with the goal to eliminate it — until the next flood event. Crews mowed designated reed canarygrass segments, about 114 acres in 2022, then sprayed it. Other portions of canarygrass were round baled during 2023.

With the above work items checked off, the uncontrolled factor is how to add water. Will enough rain happen during September? Will the Iowa River’s present low flow rate recover enough that pumps can be operated to supplement water into Otter Creek’s pools? Will too much water fall from the sky and result in minor to major flooding?

No one knows the answers to these questions. Obviously at the present time, it does not look good to get enough water into the marsh segments. The Iowa River flow level is at this time two feet below the intake of the pumping station. That means a lot of new water has to bring the Iowa River flow high enough to allow pump use.

From a duck hunter’s perspective, significant rainfall will be needed to turn around the present drought. Waterfowl will still migrate through Iowa over the next several months.

Stopping at Otter Creek Marsh, if still dry, will make them move on to other water sources at places like Red Rock or Rathbun. Such is the nature of the job at Otter Creek Marsh, where the chores never end.


Iowa’s teal season kicked off on Sept. 1. Hunters know that teal, both Blue-winged and Green-winged, may be early migrators, so an early teal-only season is allowed by the US Fish and Wildlife Service when the overall population is above certain levels.

The 16 day season is considered bonus hunting days that do not take away any days from later regular duck seasons. Water levels in production states in the Dakotas were favorable during 2023, and like clockwork, teal migrate early and will have or soon will move south. All it takes is a cold front up north and these species of waterfowl will move overnight into wetland sites across the Midwest.

Iowa DNR posts waterfowl migration updates every Friday during duck and goose seasons, and additional poses on wetland conditions are also available. According to Orrin Jones, State Waterfowl Biologist, Teal favor mudflats and shallow water areas.

Hunters are encouraged to check out potential hunting areas before assuming that a favored wetland will have enough water to be wet. Teal hunting hours begin at sunrise, which is different from the hours during regular duck seasons. In addition to the hunter’s hunting license, a state migratory waterfowl fee is needed along with a signed Federal Migratory Bird Stamp.


Also opening up for hunters will be the 2023 cottontail rabbit and squirrel season, which began Sept. 2. Rabbit meat is a lean, low fat product that is a culinary delicacy in some private kitchens.

The rabbit season goes through Feb. 28, 2024. Ten is the daily limit, with 20 in possession. Squirrels may be hunted from now through Jan. 31, 2024. Daily limit is six, and the possession limit is 12.


I attended a meeting in Baxter on Tuesday evening. It was hosted by the Iowa DNR deer biologist Tyler Harms and the topic concerned recent confirmed deer with Chronic Wasting Disease (CWD) in Jasper, Marshall and Grundy County.

Harms showed a slide depicting how the disease has slowly spread across portions of Iowa from its first confirmed site in far northeast Allamakee County in 2002. His slide ticked off more year by year advances this disease has made so that the viewers obtained an improved understanding of how it is slowly invading more territories.

So far, after 100,168 tested white-tail deer, 260 have had positive CWD results. Marshall County has one positive case — so far. One could get the false impression that all deer are carriers of CWD.

That is not the case, but there is no way to tell outwardly just by looking at a deer. Even areas of Iowa with a twenty year history of a few positive CWD deer still have a robust deer hunting cadre of people returning every fall for their special hunts.

What is the plan of action recommended to hunters? For starters, there will be an increased need to gather more data and test more deer. All deer hunters are highly encouraged to contact area wildlife biologists to assist in obtaining the lymph node samples from a deer’s neck area.

Second, meat from a positive deer may be utilized if the hunter desires but discretion is recommended in this process. The disease is not known to cross over into humans.

Thirdly, CWD takes a long time to show itself in a deer. It can take three to five years before a deer exhibits outward body condition degradation from CWD.

A photo was shown of a hunter with a very normal and healthy looking buck deer that did get sampled after it was taken. That test turned out to be positive.

Fourth, mature buck deer tend to be more likely to contract CWD. Fifth, getting deer sampled and the results of a negative (or positive) test before complete processing of the meat is encouraged. Hunters and even locker plants will have to identify and keep separate deer carcasses into negative tested and positive tested.

The problem for deer that are positive for CWD is that it is 100 percent fatal, and it takes years for the disease to progress sufficiently enough to take its life. It is a serious problem in 31 states and four Canadian provinces.

Members of the deer family — moose, caribou, mule deer, whitetails, and elk — can get CWD. I’ll have more updates on CWD contacts and testing in a future column.


September is here. Look for day lengths to get shorter from the 13 hours, 11 minutes on Sept. 1 to 11 hours and 50 minutes by the end of the month. Air temperatures during September will also begin to cool off.

In the first of the month an average high can range from 79F to 59F. By month’s end, the average high will have dipped to 69F with a range down to 48F. Average rainfall events can add three to four inches. Fall season begins officially on Sept. 23.


Garry Brandenburg is the retired director of the Marshall County Conservation Board. He is a graduate of Iowa State University with a BS degree in Fish & Wildlife Biology.

Contact him at:

P.O. Box 96

Albion, IA 50005


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