I'm breaking ground shortly on an 11 acre foot oval shaped pond that will be 20' deep with 2/1 interior slopes all around. It's to store water for irrigation, but most years, we'll only draw it down between 10%-30%. Location is northern California (west Sonoma County).

What are the indispenseable maintenance steps I need to implement as soon as the pond fills up for the first time this winter? May consider fish later, but for now, I just want to avoid run away problems with water quality, the underwater living environment and the plant community along the variable water's edge.

I appreciate that some maintenance techniques are highly site specific. In my area, Summer is dry and generally mild, and winter is cool and rainy.

On the other hand, I suspect there are some essentials that should be considered regardless of where you are located. For example, should I give serious consideration to installing an aeration system because it is certain to pay greater dividends in decreased chemical or physical maintenance down the road?

I am happy "do nothing" and see what develops, but my instincts tell me that "an ounce of prevention" with a pond of this size is "definitely going to be worth a pound of cure."

Thanks in advance for your thoughts and suggestions.

Welcome to Pond Boss!

There is a lot of information to convey both ways to help you.

While others chime in, did you go through a formal process in your state to plan the pond, or are you just making it happen?

I'd plan on having some type of small fish in there to minimize the amount of living mosquito larvae. Be it Gambusia or Fathead Minnows. The intake of the irrigation system will need to be screened so you don't plug your sprinkler system with ground up fish parts. That's just the first thing of many....

Welcome to the forum!

Yes, the pond is fully engineered and permitted. The civil and soils engineers will also work with contractor during construction to deal with any issues that may crop up.

The only "intake" that there will be is the 1 1/4" intake end of a shallow well jet pump. Only need to transfer 20-30 gal/min to the IR tanks when we're irrigating. I suspect that it will be easy enough to keep the foot valve clean on the pump intake.

What sort of grass or other plants, if any, should I consider planting around the water line to prevent the establishment of unwanted (i.e., invasive) weeds or grasses?

If I do nothing to aerate and/or manipulate the chemistry of the water, am I certain to see problems that will require a great deal more effort to correct?

My engineers and contractors have built alot of ponds, but they haven't had to maintain a pond well after it was built. Hence, they don't have much guidance to provide on the "must do's" once the thing fills up.

Thanks, jr

Be careful about that plant community. It can get out of hand in a hurry.

Check for leaks.

Expect the pond to rise and then drop some. It is wicking back into the surrounding dirt.

Bump??

Other than the mosquito control and checking for leaks, what should a new pond owner like me plan to do to maintain water quality and manageable bank vegetation? Climate is coaatal Northern California. Would installing diffuse aeration from the start ensure a healthy pond with a minimum of chemical and/or physical maintenance? Is there certain non-invasive vegetation that I can plant that will help prevent invasive vegetation from establishing itself? Or is it preferrable to try to maintain some amount of bare ground near the pond's edge (e.g., with tillage, compatible herbicides, etc.)?

I'd prefer not to wait until I'm staring at an out-of-control problem before I do some maintenance. Thanks!!

Riddler, I'm a plant guy(vs structure) and I'll tell you this. Not sure what invasive species grow in N CA, but as Dave said be careful. Most shoreline plants that I like are slow to grow, so therefore don't always out compete invasives. You can plant something like Arrowhead, that grows well, but still allows Primrose to grow outside it. When this happens, you wind up spraying the Primrose, and killing the Arrowhead with residual spray.

The only plant I've personally experienced that will keep other invasives in check is American Lotus, and it's a bear to control as well. It is a bad invasive also, but it seems to choke out everything else. That's why it's such a nuance.

If it was me, I'd get the shoreline sodded and clear of weeds below the future waterline, and then go from there. As a general rule, I spray agricultural herbicides no closer than 4' from the waterline, then aquatic herbicides on the water's edge. Again, it's just my experience, but bare soil at the pond's edge creates all kinds of weed problems.

I will add this. If you're drawing down the water up to 30% a year, shoreline invasives are much easier to control naturally, but also hinder any preferred plants.

Just my 2 cents.

Al, your thoughts are exactly what I'm looking for.

We always have glyphosate based herbicides (i.e., Round Up) on hand for other purposes. What is the "aquatic" herbcide of choice? I can stock some it as well.

The pond will probably be drawn down at least 15%-20% each year. Not sure we'll hit 30%, but we might.

I am not familiar with Arrowhead, but I will check to see if it grows well in my climate. What other shoreline plants do you like, nothwithstanding their slow growth habits?