Some are referring to it as the swimming hole for Laconia City Hall's employees and others are calling it a wading pool.

One thing is for sure: People are talking about the hole being dug behind City Hall and its smaller clone behind the old police station.

"Fear not," said City Manager Eileen Cabanel. "They're a rain garden."

Designed by Public Works Engineer Kevin Dunleavy, the two rain gardens are part of the storm water runoff portion of the Laconia Riverwalk project and are designed to keep pollutants from running into the Winnipesaukee River.

When finished, Assistant Planner Seth Creighton said, each garden will have a variety of plants and will look like a garden. The various layers of silt will absorb the rain runoff.

Although this hole beside Laconia City Hall is a bit of an eyesore at the moment, it soon be a rain garden and oil separator for the city hall parking lot. (DARYL CARLSON/CITIZEN PHOTO) * Order a print of this photo

In a memorandum to City Planner Shanna Saunders, Dunleavy said they chose a "bio-retention" bed for a number of reasons but mostly because the city did not want a retention pond that could act as a breeding ground for mosquitoes; nor was a traditional catch basin because the water table is too high relative to the river.

Dunleavy said the area is exempt from the N.H. Department of Environmental Services purview but the rain garden "may be considered a new technology, they are quickly becoming the norm for proven storm-water treatment" and are, by no means, "cutting edge ideas."

He said the advantages are a relatively low cost and they are relatively attractive for those people walking along the Riverwalk. They are necessary because the Beacon Street parking lot is domed to prevent puddling and, as it stands now, there is no storm-water treatment so runoff goes directly into the river.

Dunleavy said that, even following a big rainstorm, the water should be absorbed within 24 hours.

Crieghton said the garden may be ready for planting this fall but, depending on the weather, the city may wait to plant until next spring.

When finished, the rain garden will have silky dogwood shrubbery with black-eyed Susans, Caesar's Brothers Iris, meadow sweet feather reed grass and bee balm.

Dunleavy said the two rain gardens would need maintenance like any other gardens.

Cabanel said the rain garden behind the City Hall cost the city a few parking spaces.