Thanks for all your patience, folks.

How do you manage the interaction of plants and animals in a large water system? What problems do plants and fish cause in the canals, and how do you take care of them? What about beaver?

Plants and animals?!! HAH HAH HAH HAH Hah Hah hah hah hah!! Take care of PLANTS and FISH in your canals!!!! HAH HAH HAH hah hah hah hah ha ha ha. Oh holy shit that was funny. HAH HAH HAH hah hah hah. Oh ho. Operate your canals for fish. HAHHAHHAHAHHAHHA. Hah hah hah. That cracks me up every time I think about it.

We don’t do that. Well. I mean, barely, some people do. But mostly we don’t do that. You tend the fish and plants with pesticides is what you do. Beaver? I believe you meant to say vermin. What you do if you encounter an endangered fish in your system or giant garter snakes on your canal banks is you SHUT YOUR MOUTH and hope no one else ever sees it.

From what I’ve seen, district level water systems and natural systems within a district are thought of entirely differently. Natural systems are, like, cricks. They’re all pretty, so you go fishing in them with your boys and shoot the waterfowl. There is some fair respect for any remnant streams and concern for wildlife in them. However, you will simultaneously have a separate and parallel controlled system for getting water to every field in your district and drainage ditches from each field*. Friends, those are incredibly extensive; every agricultural field in the west is reachable by a rudimentary road and by one or two ditches.

The built system is built for irrigation and that is the purpose district operators use it for. Introducing a secondary purpose, like acting as habitat for fish and wildlife, compromises how well the system can accomplish the first purpose. But it is undeniable that the canals and ditches serve as habitat by default. There’s so little else left out there. There are fish in canals; they are frequently fished**. Plants grow on the banks; those can transpire noticeable amounts of water. They’re usually mowed or killed by herbicide in the summer. One district I visited last summer gets non-native aquatic mosses in the summer; he said they take up over half the capacity in the canal. They can’t poison the moss (the herbicides would damage the crops that water is later applied to), so they spend about a third of their O&M budget on chaining the canals to shake the moss loose. Imp*rial Irrig*tion D*strict controls the plant growth in their canals by stocking them with sterile grass carp. But the district I visited can’t do that because the carp could escape in flood flows, and who knows if they could revert to fertility like in Jurassic Park and become velociraptors. Whether a canal has plants in it is a standard design question; the extent of the plants dictates the way you have to screen your pumps or gates or whether you can install propeller meters.

The drainage ditches end up doing more work as habitat. They aren’t managed for that, either. They carry sediment, pesticides and fertilizers in them. A real pollutant, actually, is heat. Water warms up in fields before it enters the ditches. Warm water holds less oxygen in it and can drown fish that aren’t adapted for it. But for all that, drainage ditches are fairly neglected and that neglect may be the best option fish and wildlife have.






I wish I could tell you more about how natural systems and water districts interact. I wish I knew more about FISH SCREENS and FISH LADDERS. I wish I had a friend who designs that stuff and tells me my blog is boring when I talk about dating. I sure wish she would come on here and tell us how the pumps at the Red Bluff diversion dam work, since they were designed by Archimedes and everything. Or why installing fish ladders would make those four dams on the Klamath more expensive to keep than to pull out.








*I know you’ve wondered. Tilewater is water that has percolated into your field and is collected in a system of pipes a few feet beneath the ground. (You have to be careful not to rip up your tilewater system when you plow.) I think those are mostly pvc now (with holes in the side, so water in saturated soils will enter the relatively low pressure pipe and be drained away), but they used to be ceramic tile pipes. They collect water and drain it to a sump or drainage ditch. Depending on the soil, it may be fairly salty or selenium-laden (for example).

Tailwater is water that runs off the surface of your field into a drainage ditch. You get tailwater re-circulation systems that’ll pump it back up to the head of the field (if water is more expensive than electricity in your area). Tailwater may pick up some sediments, but it probably won’t be much saltier than the incoming irrigation water.

**My awesome irrigation professor taught us to design all canals with safety haul-outs, so that people who fall in, primarily from fishing, can get themselves out. You can see the ladders in the California Aqueduct. The other primary use of canals in ag districts is as make-out spots; you regularly find nests of empty beer cans and used condoms on the banks. My professor also told us that if you design water projects for third world countries, you MUST include shelves for doing laundry. It is unavoidable, he said, so build facilities so that people don’t drown trying to wash their clothes.