Ruminations as we develop and manage a small farm in southeast Iowa. Click photos for larger images. Click here for farm map.

Thursday, May 10, 2012

Dam Maintenance

The principal spillway for the dam is a four-inch diameter pipe. The image is of today's early morning sky and a waning gibbous moon sailing among clouds of algae. Donna & I have now been out in the canoe with a sprayer, applying an algicide to what's become a serious bloom of the stuff, which starves other aquatic life of oxygen. We're assured it's not a poison but a dye that interferes with the algae's ability to photosynthesize. Saturday we pick up the bass and catfish to stock the pond, the next step in enhancing the ecological and recreational value of this asset.


The dam seems to have gotten little maintenance since construction. Typically one would control for woody vegetation, burrowing animals, erosion and similar threats to the integrity of the compacted fill. Erosion is not a threat here, but there are large trees on the downstream embankment, mostly black cherry and some willow, and lots of undergrowth, thickets of native dogwood and invasive honeysuckle, but also wild grape, gooseberry, and raspberry. I've been clearing it out, so far just the trees I could cut with the giant compound loppers. Here's the view to one side of my starting point:


And here to the other side:


Next: taking a chainsaw to those remaining trees up to about four inches diameter. The limit is somewhat arbitrary, but the larger the tree the more problematic its removal because rotting roots leave channels in the fill that weaken the structure and can convey seepage.

Here's a mystery I encountered. Along a line about five vertical feet above the toe of the dam, I found several of these strange things. The holes are about two inches in diameter, about ten inches apart. One seems to go "in" and the other "out". The out hole seems like an enormous worm casting, or as if a very liquid sand-mud mixture had belched from the ground. I intend to keep an eye on these things. Update: Donna's research indicates these structures are made by voles, and we've now seen them in various places, usually near water.


Last evening we drove up to Tipton to meet D&G for dinner at a quite nice family Mexican place, and got some good advice from them about noxious weeds and vegetable gardening.

Almost every day, it seems, we spot a new species of wildlife. Yesterday it was a mink. Last night I dreamt of the bobcat. This place is getting pretty deep inside me.

1 comment:

  1. After further study it looks like our mounds may be the work of voles. Voles or crayfish, but the crayfish would have to be awfully dumb to build their homes just across the driveway from a pond :P

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