Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Ephemeral pond © Drew Feldkirchner

To learn more about ephemeral ponds visit dnr.wi.gov and search keywords "ephemeral ponds".
© Drew Feldkirchner

June 2013

Often overlooked

Ephemeral ponds deserve our attention, too.

Cary Kostka

Ephemeral ponds are a vital but often overlooked component of wetland systems in our state, and as such need the same TLC as other wetland systems. By learning more about ephemeral ponds, better protection strategies can be developed.

What are ephemeral ponds?

Ephemeral ponds are formed from winter runoff and spring rains. These ponds are temporary and typically dry out by early summer, though this is dependent on other factors such as seasonal precipitation and temperature. Ephemeral ponds do not have inlets or outlets, and are isolated from other wetlands, making them fully reliant on winter snows and spring rains. Because they don’t have inlets and dry out each year, ephemeral ponds do not support fish populations. They provide habitat for a diverse collection of invertebrates, amphibians and plant life, including wood frogs, blue salamanders, fairy shrimp, turtles, dragonflies, damselflies, pond snails, water sow bugs, smartweeds and orange jewelweed. The first three species mentioned are considered ephemeral pond indicators, because they spend most, if not all, of their life cycles in these ponds.

Ephemeral ponds and ecology

The diversity of species that rely on ephemeral ponds is key to local ecologies. The variety of plants that ephemeral ponds support provides a place for songbirds to breed, feed and rest. Amphibians and certain invertebrates rely on these ponds for breeding and maturing. Small mammals and migrating waterfowl find food sources here as well.

The isolated, still nature of these ponds complicates life for ephemeral pond species. Ephemeral ponds are shallow and have no currents so the water warms quickly and has lower levels of oxygen. Shallow, warm water with little oxygen evaporates quickly so time is not on the side of these species. To cope with unpredictable, ever changing conditions, many of these species can hasten their maturity into adulthood to beat the pond drying out.

Autumn leaves become a part of the food supply for invertebrate residents of woodland ponds which have longer life cycles since the surrounding trees provide cooling and shade, reducing evaporation. Many species reliant on ephemeral ponds bury their eggs in the mud, where they wait for the spring melt to hatch. Plants add energy to the pond by becoming compost at the end of their growing season. Plants also attract birds, insects and small mammals, whose waste products add to the natural composting process in and around the ponds.

The need for conservation

According to the DNR’s "Species of Greatest Conservation Need" list, 12 species of birds, mammals and amphibians are listed as being "significantly associated" to ephemeral ponds, with another six species listed as having some pond association. Those 18 species reliant on ephemeral ponds can best be helped by furthering ephemeral pond protections.

The primary natural threat to ephemeral ponds is drought. A lack of precipitation, like Wisconsin experienced in 2012, can have wide ranging effects that we may not see for two to three years, according to Tom Bernthal, the DNR’s Wisconsin Ephemeral Ponds Project (WEPP) manager.

What if drought conditions persist? Jim Hyatt, WEPP program director for the Schlitz Audubon Nature Center writes that he would, "imagine that these species would have to find any source of water, even a permanent pond." He adds, "Permanent ponds also have more predators. This would mean a decline in the population of amphibians."

 Salamander camouflaged by leaves. ©Carman Wagner
Ephemeral ponds provide critical breeding habitat for some rare birds, mammals, reptiles and amphibians.
© Carman Wagner

Landowners and developers also threaten ephemeral ponds by draining and filling them, perhaps unintentionally. Since ephemeral ponds are considered part of the Wisconsin wetland system, anyone wishing to drain, fill, or make any other changes to an ephemeral pond must first seek a permit with the Department of Natural Resources.

But how do you know if the pond is ephemeral? Identifying ephemeral ponds is a challenge, as many remain unmapped in the state.

Mary Hollebeck, Adult Program Coordinator at Riveredge Nature Center, says, "The biggest challenge is getting permission from landowners to monitor their ponds. Another challenge is that not all temporary ponds are ephemeral ponds. This is why surveying potential ephemeral ponds, and mapping out those that prove to be ephemeral, is so crucial and an important goal of WEPP."

How to help

WEPP currently focuses its conservation efforts in the eastern and southeastern part of the state. According to Katie Beilfuss at Wisconsin Wetlands Association, the focus is on these areas because they have the fastest development growth. The ponds in these areas are at greater risk, making the need to map them sooner rather than later a must.

WEPP volunteers have monitored ephemeral ponds since 2008 with local partners throughout eastern and southeastern Wisconsin. WEPP partners monitored over 150 sites in the first two years of the program. Those interested in helping can do so by volunteering to be a part of the Citizen Monitoring Network. A listing of partners can be found at http://watermonitoring.uwex.edu/ level1/wepp/index.html

Volunteers are required to attend an eight-hour training session and are expected to monitor a minimum of three sites on a monthly basis from April through October, or until the ponds have dried out. Volunteers in the project work in teams of two or more, and enter various measurements and readings onto a supplied one-page datasheet. A common request from organizers is that if you decide to volunteer, be consistent and stick with the program through the entire season.

Making a difference

Hollebeck adds, "Since WEPP’s inception, hundreds of ephemeral ponds have been verified in southeastern Wisconsin, which hopefully will ultimately lead to their protection."

According to the Milwaukee County Parks/UW-Extension Natural Areas Program, 306 ephemeral ponds have been located and inventoried in the Milwaukee County Park System. The program only has the Menomonee River and Little Menomonee River corridors left to survey in Milwaukee County.

Brian Russart, the Natural Areas Coordinator and primary contact of the program, says that the project should be completed within the next year or two.

Conservation efforts of programs like WEPP and the Milwaukee County Parks/UW-Extension Natural Areas Program are yielding good results thanks to their dedicated efforts. Although ephemeral ponds have fallen below the conservation radar of most Wisconsin residents, awareness is growing. By raising awareness, ephemeral pond conservation efforts will continue to grow, ensuring that their dependent ecologies continue to thrive for generations to come.

The Department of Natural Resources Wetland Identification Program helps residents determine wetland presence on their property. For more information, Visit Wetlands benefit people and nature or the interactive webmapping tool at Surface Water Data Viewer .

Cary Kostka has participated in the Wisconsin Ephemeral Ponds Project through the Schlitz Audubon Nature Center in Bayside. He writes from Cedarburg.