Man I'm glad I found PondBoss. I was pulling my hair out trying to figure this stuff out on my own. Just a quick summary of my situation: I have a 2-acre pond in Central Texas that was recently (3 years ago) expanded from an old stock tank on the 8.5 acre property I bought. The developer put just enough money into the expansion to give the appearance of a nice big pond. The problem is he only dug it to an average depth of 2-3 feet (4-5 feet at the dam). I'm now looking to renovate the pond and increase the depth, add structure, restock, etc. I have contacted dirt movers, pond builders and lake management contractors who all have different ideas and obviously costs. I want the pond to be primarily a LMB fishery with no real concern for swimming or other uses.
I have a LOT of questions but here is my first - I have a fairly large watershed that dumps a lot of water into the pond during heavy rain events. There is an existing 24" corrugated culvert pipe in good condition passing horizontally through the damn and an emergency spillway (not concrete) on the left side of the damn. This spring we had 5" of rain in about 2 hours and the spillway was flowing knee deep and 20' wide. Normally, though, a decent rain would just flow out the pipe and keep the level consistent. One contractor said he would remove the pipe and lower the spillway to pond level. Does that make sense or should I keep the pipe or use another type of outflow device? I've seen other types but I don't know enough to know what I really need and why.
Thanks for your help
Google Earth pic : [img]http://maps.google.com/maps?t=h&hl=en&ie=UTF8&ll=30.494788,-96.264589&spn=0.002538,0.003465&z=18[/img]
I would give Mike Otto at Otto's Dirt Service a call. Bending one more ear wouldn't hurt and he has a bunch of experience with ponds.
An emergency spillway is just that, for emergency usage if the primary spill device can't handle the volume of water. If the dirt spillway is used continually for overflow, the dirt will erode, leading to a dam failure. He will know (providing you furnish him with enough information) on whether or not your primary spill pipe is large enough for your watershed.
Ok, thanks, I'll definitely get in touch with Mike.
Your comments on the spillway are exactly what I thought. It makes sense to me to have a pipe to keep the pond level consistent without making a muddy mess and risking erosion during a big rain. I just wonder why that contractor wanted to get rid of it. There has been absolutely no leakage and the pipe looks in great shape. Are there reasons besides leakage to do the drain differently? Another contractor mentioned a vertical drain pipe. How exactly does that work and is it better for some reason?
I'm obviously a newbie so feel free to point me to previous posts or articles I haven't seen yet. I've been reading as much as I can but there is a tremendous amount of information at PB. Thanks again for your comments.
Looking at the aerial picture, I have another idea for you to think about. If the spillway flows knee deep, that means the watershed is large enough to support a bigger lake. Consider this. If you raised the dam and the spillway a few feet and raised your overflow pipe with an extension, you could gain the depth you need by going up instead of down. That's a lot less expensive. Get the dirt from the periphery of the pond that will become the new shoreline by digging channels, cuts and creating shoreline fish habitat/cover and use that dirt to raise the dam (if it is good dam building material). That kills many birds with one stone. First, the rest of the lake becomes 3-4 feet deeper by raising the dam. Second, build your bass fishing paradise around the edges. Third, take the dirt you build you structure/habitat/cover with and raise the dam. Win, win, win. And, it's the least cost to get what you want....as long as the dirt has enough clay to compact into the dam.
Teach a man to grow fish... He can teach to catch fish...
Plus that plan gives you more water (deeper water) to withstand a drought. The greater the % surface area to the total water vol the faster it will evaporate.
I wish it were that easy. I read the article about going up instead of down but in my case it won't work completely. The dry creek that feeds the pond with runoff has a very slight slope and I would back the water up into that creek with very little additional water. I had to add 3' of fill to my back yard to keep the pond from encroaching into a marginless, swampy marsh. There are also 6-8 mature oaks on the north side that would be flooded. I might be able to go up by 12" or so but the rest will have to be dug unfortunately.
On the bright side we have some of the best clay around for building ponds and dams so our thought is to thicken the dam and extend it away from the spillway and deepen the entire pond.
I'm pretty sure there wasn't an engineering effort that went into sizing my drainage pipe so it could probably stand to be a little bigger. The E-spillway has topped over twice in the last 3 years but they were both pretty big spring rainstorms. Any thoughts on what type of pipe to use, and in what configuration, if we decided to upgrade? Is the un-hooded horizontal pipe sufficient or should I look at a vertical standpipe?
Deepen at least some spots and shallow areas and raise the dam some. Change the pipe to an adequate siphon as it will move more water faster and it will be bad bottom water rather than your good top 2 feet.
A 4-5 ft deep pond in the south is set for water problems. With summer stratification you can have DO problems limiting the fish to only the top 2 feet of water. That is too stressful for good fish growth. Shallow water also is subject to rapid temp change which can cause problems in winter. It also is prone to plant problems.
May be able to use 2 pipes - old one and a smaller siphon.
See what Mike suggests - an eyes on opinion is much better. Tell him your concerns. He has excellent creative instincts and experience. My 2 cents - you need some deeper water.
Just got off the phone with Mike and he recommended cutting the dam to drain the pond so we can get started. He also highly recommended replacing the CMP drain with a plastic or aluminum one for longer life. He said we MAY be able to elminate the pipe altogether since we have a flat rock- and gravel-lined spillway that shows no erosion problems during flood events. That's all based on a site visit after the pond has drained and fish removed of course. I'll post pics once the project is underway.
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