Hand-digging Vernal Pools in New Jersey

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cbernz
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Hand-digging Vernal Pools in New Jersey

Post by cbernz »

If you have the space, and you live in the right kind of area, building small vernal pools on your property can be a fun and satisfying project. I built my first one in the fall of 2011, after being inspired by this detailed PDF about vernal pond construction: http://herpcenter.ipfw.edu/Outreach/Ver ... dGuide.pdf There are many methods you can use to build vernal wetlands, but I discovered that I was able to build mine very simply with practically no specialized equipment. After 2 years, my pond is doing quite well, and I decided to build another larger one this fall, using the same easy method.

I live in Morris County, NJ, in a semi-rural area just south of Great Swamp NWR, the largest and best-known preserved area of the Passaic Meadows. The Meadows are the remnants of an ancient glacial lake, and include swamp, marsh, floodplain forest, bogs, and other habitats that are home to some pretty interesting herps, including a certain turtle and the southernmost population of Blue-spotted Salamanders. This whole area is full of vernal wetlands of all types, due to the high water table and frequent flooding. Here are some nearby "wild" vernals that I photographed this week:

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This is a small, fully shaded (surrounded by trees) vernal pool. We are having an exceptionally dry autumn, so it is totally waterless right now.

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Here's a larger, deeper, mostly shaded pool.

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This one is only partially shaded, and therefore has a greater diversity of grasses and other plants.

My property is on a quiet residential street that dead ends at the Passaic River on a small NWR parcel. From the street, my 2-acre yard slopes down towards a small red maple woodland drained by a small creek. The woodland extends in a narrow strip all the way up to the Passaic and to the Great Swamp. The site I chose for my first vernal pool is right where the lawn meets the woods. The first thing I did was dig several deep test holes to find out what my soil was like. I made them about 2.5 feet deep. The main thing you have to worry about with constructing a pond is water retention. If the soil is too loose or gravelly, you need to buy a liner, or use some elaborate construction techniques. What I found, to my delight, was that not only did I have some beautiful solid clay about 20 inches down, but my holes almost completely filled with water in a couple days, indicating a very high water table. This meant that all I really had to do was start digging, and as long as I dug deep enough, the pool would hold water for much or all of the year.

I don't have any photos of the construction process of this first pool, but I will go into more detail on the second one. Here is the pool as it appeared the day I finished it in November 2011:

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The hole is about 25 feet long and 15 feet wide at maximum, and 3 feet deep at the deepest end. I dug the entire thing myself, over the course of a couple weeks, using only a shovel, heavy duty pruning loppers, a small pruning saw, and a wheel barrow. The tarps are covering the fill dirt that I used to make a berm on two sides of the pool. Once I finished digging, I spread a couple inches of topsoil over the entire area, and then several inches of dead leaves over that.

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Here's what the pool looked like 3 days later, just from groundwater seeping in.

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After another 7 days and a few rainstorms, the pool was completely full of water. You can see that I added some branches and logs for cover and egg deposition sites for amphibians.

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This is what it looks like now, after 2 years. I've found quite a few amphibians and insects breeding in the pool over the past couple seasons:

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The first species I found in March, 2011, was this one, the newly described Leopard Frog whose name I don't know yet (does it have one?).

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This year I found this pair of Wood Frogs, so far the only vernal pool obligate species I've seen here.

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Wood Frog eggs.

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Northern Gray Treefrogs sang from the grass around the pool this May.

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Gray Treefrog tadpole. I had never seen one before. They hang from the surface looking just like little diseased leaves.

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My daughter holding one of the many Green Frogs that live in the pool.

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Great Blue Skimmer, one of several dragonfly species I've found breeding in the pool.

I'm very pleased so far with this vernal pool, and it's already a great little habitat, but of course the only thing better than one vernal pool in your yard is two, so this October I started digging a second one. I wanted the new one to be considerably larger than the first one, but also much shallower than the first, so that it would periodically dry out. My first pool, even in this drought, still has at least 18 inches of water.

Here is the bare site:

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It's just a few yards downslope of the first pool, which is basically hidden, just left of the bird house. The ground slopes gently downward from the background to the foreground, and also downward from right to left.

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Step one in the process is to dig out the top layer of soil. With the shovel method, this is by far the most tedious and difficult part of the project. Since the site is next to woods, this top 8-10 inches of soil is packed with tree roots, in addition to grass and grassroots. I started by digging a narrow trench (2 shovel widths) marking the perimeter of the pool, then cut out chunks of turf, soil, and roots using the spade and a pruning saw. Most sane people would probably just rent a bulldozer or steam shovel for this, but I had a lot of free time, I like manual labor, and I enjoy the feeling I get looking at something I built by hand.

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My daughter helping out. I dumped the wheelbarrows full of dirt at the downslope edge of the pool to form a berm that will help contain the pool during high water.

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Step 1 complete. The top layer of soil is gone, and you can see the low berm of soil along the back edge.

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Step 2. I decided where I wanted the deepest area of the pool to be, and dug a narrow trench to mark it off (visible in the center of the photo). Then I dug about 8-12 inches of soil out from this area, making a deep area about 12-16 inches below the level of the grass. Due to the slope of the terrain and the berm constructed at the back, this area will actually be somewhat deeper, because the water at the low end of the pond will rise a little above where the soil used to be.

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Step 2 mostly finished. The darker reddish-brown area is the freshly dug deep section. The berm has grown with the additional soil, and I've used the spade to slope the sides of the pool as naturally as I could.

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You can see the deepest parts of the pool after a brief rain. The very next day, these puddles were gone. The water table is pretty low right now, well below the deep end of the pool, but in a normal autumn, this whole pool would probably have 4-8 inches of water, at least.

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With the fallen leaves covering the whole site, it looks fairly natural. I'll try to post an update once the pool fills in and starts getting some action.

Over the past couple weeks, I've been going out every now and then to do a little soil sculpting: shaving down a couple of the sides, making the deep end slightly deeper, taking off a bit more of the grass layer, and tamping down the soil on the berm by walking back and forth on it. Several times already, I've decided the digging is done, but since we continue to have this drought, and the soil is dry, I keep going out and digging some more. Just to give you an idea of the weather, our average rainfall for the months of October and November is about 8 inches, and we have only had about 1.25 inches. Not great for the environment, but fantastic for digging.

Once the digging is done, the only other concern is erosion control. With my first vernal, I used tarps over the exposed soil, and later seeded it with winter rye. My new pool is much broader and shallower, and I am less concerned about erosion. I'll probably compact the steepest areas with my feet, and maybe cover them with dead leaves. After the ground freezes, erosion won't be a problem at all until spring, at which point I can mulch or seed the areas of exposed soil. One of the advantages of the shovel method is that you only minimally disturb the soil, so there is far less loose dirt lying around than there would be if you used a bulldozer or other heavy equipment.

Anyway, this has been a fun ongoing project for me. I hope this post will be of use or interest to some of you. My method certainly won't work everywhere, but I hope I showed that building habitat on your property can be a fairly simple and rewarding experience. If you have the room, and if you can hear, find, or know of vernal pool breeding species in your area, I highly recommend trying to build a vernal pool.

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umop apisdn
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Re: Hand-digging Vernal Pools in New Jersey

Post by umop apisdn »

That's pretty awesome. I can't wait for the day I can afford a piece of property to call my own. I've tried convincing my parents to make their yard more herp-friendly since I was a kid, to little avail. Fortunately, my mother developed a taste for gardening throughout the yard, and it has served to make the yard more wildlife friendly in general. As a result, I've seen herps around in the past couple of years that I hadn't seen in the previous 20 years.

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John Martin
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Re: Hand-digging Vernal Pools in New Jersey

Post by John Martin »

Dude, you are a complete nutter :shock: , and a kindred spirit! :thumb: Many kudos for taking such a great amount of time and effort to give Mother Nature a bit of a helping hand - well done!!

Tamara D. McConnell
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Re: Hand-digging Vernal Pools in New Jersey

Post by Tamara D. McConnell »

That is just beyond awesome.

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chris_mcmartin
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Re: Hand-digging Vernal Pools in New Jersey

Post by chris_mcmartin »

Very cool! Coming from the comparatively parched Southwest, the thought of a high water table amazes me. :lol:

jspreitzer
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Re: Hand-digging Vernal Pools in New Jersey

Post by jspreitzer »

Great post. That is some wonderful work that you are doing!

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justinm
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Re: Hand-digging Vernal Pools in New Jersey

Post by justinm »

My parents still own the 37 acres of upland forest I grew up on. I'm going to see if they wouldn't mind me making at least one vernal on the property. Awesome post man, I love it.


Justin

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BillMcGighan
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Re: Hand-digging Vernal Pools in New Jersey

Post by BillMcGighan »

OK,
That's the best thing since jelly beans.
Sincere Kudos for doing that.
There was no shortage of natural pools where I grew up in Sussex County, but I still would have liked one close to the house for observation.

Makes me want to get off my butt and do the same here in the southern Appalachians, since many of the vernal pools are incidental to the NFS scooping holes and building mounds to keep folks from driving on closed roads (our glaciers down here were alpine not contiental.)

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cbernz
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Re: Hand-digging Vernal Pools in New Jersey

Post by cbernz »

Thanks, guys.
John Martin wrote:Dude, you are a complete nutter :shock: , and a kindred spirit! :thumb: Many kudos for taking such a great amount of time and effort to give Mother Nature a bit of a helping hand - well done!!
Yeah, I'm definitely a nutter. I'm also trying to kill half my lawn by smothering it with wood chips so I can turn it into a wildflower meadow. So far it's been an exercise in futility. The wood just turns into mulch that the invasive grass grows right on top of.
justinm wrote:My parents still own the 37 acres of upland forest I grew up on. I'm going to see if they wouldn't mind me making at least one vernal on the property. Awesome post man, I love it.


Justin
Thanks. You should definitely look into it. Read through that PDF - it should give you all the info you need. Where is the property?

I left out a couple things from my post. After I built my first pool and it filled up with water, I went to a nearby vernal and took a few liters of water and muck to "seed" the new one. I'm not sure if this is totally necessary, because many microorganisms and invertebrates are either already in the soil or eventually find their way to vernal pools, but I figured it gave a bit of a head start to the pool's biodiversity.

The other thing worth mentioning is being careful about your trees. I had to cut through quite a few tree roots to build the pond. I am not a tree expert at all, so I was kind of concerned about accidentally killing trees when I built the first one. The two closest trees, a catalpa and a red maple, had pretty much all the lateral roots severed from about 90 to 120 degrees around their trunks (roughly a quarter to a third of the entire circumference). That seems like a lot to me, but I have a lot of trees, so I did it anyway and just waited and watched, hoping they did ok. I can find no visible signs of stress in either tree after 2 years. I cut through roots of a lot more trees this time, so I will be keeping an eye on these trees in the next year. I guess the bottom line is if you have any concerns about damaging or killing your trees, do some research on how much root damage they can take, and definitely don't try to dig a vernal next to any prized specimens.

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klawnskale
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Re: Hand-digging Vernal Pools in New Jersey

Post by klawnskale »

Bravo! An ambitious and commendable project! Amphibians need all he help they can get!

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justinm
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Re: Hand-digging Vernal Pools in New Jersey

Post by justinm »

cbernz wrote:Thanks, guys.
John Martin wrote:Dude, you are a complete nutter :shock: , and a kindred spirit! :thumb: Many kudos for taking such a great amount of time and effort to give Mother Nature a bit of a helping hand - well done!!
Yeah, I'm definitely a nutter. I'm also trying to kill half my lawn by smothering it with wood chips so I can turn it into a wildflower meadow. So far it's been an exercise in futility. The wood just turns into mulch that the invasive grass grows right on top of.
justinm wrote:My parents still own the 37 acres of upland forest I grew up on. I'm going to see if they wouldn't mind me making at least one vernal on the property. Awesome post man, I love it.


Justin
Thanks. You should definitely look into it. Read through that PDF - it should give you all the info you need. Where is the property?

I left out a couple things from my post. After I built my first pool and it filled up with water, I went to a nearby vernal and took a few liters of water and muck to "seed" the new one. I'm not sure if this is totally necessary, because many microorganisms and invertebrates are either already in the soil or eventually find their way to vernal pools, but I figured it gave a bit of a head start to the pool's biodiversity.

The other thing worth mentioning is being careful about your trees. I had to cut through quite a few tree roots to build the pond. I am not a tree expert at all, so I was kind of concerned about accidentally killing trees when I built the first one. The two closest trees, a catalpa and a red maple, had pretty much all the lateral roots severed from about 90 to 120 degrees around their trunks (roughly a quarter to a third of the entire circumference). That seems like a lot to me, but I have a lot of trees, so I did it anyway and just waited and watched, hoping they did ok. I can find no visible signs of stress in either tree after 2 years. I cut through roots of a lot more trees this time, so I will be keeping an eye on these trees in the next year. I guess the bottom line is if you have any concerns about damaging or killing your trees, do some research on how much root damage they can take, and definitely don't try to dig a vernal next to any prized specimens.

I'm going to read over the PDF, my family bought up all the forest in the area to keep it from development. So we're good stewards of the land. It's in Central Illinois, Tazewell county. So I could do this at the other forest the family owns as well, we have each side of the street. The other side away from the house was sold, partially to some folks so that they could have the lake on their property to fish on it and whatnot. I could probably do whatever I wanted on this side of the property. There are more herps on the forest with a lake on it, which makes sense.

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Mike VanValen
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Re: Hand-digging Vernal Pools in New Jersey

Post by Mike VanValen »

I remember you mentioning this project several months ago. Awesome job! This would make a great Herp Nation magazine article. Hopefully you attract some salamanders this coming spring.

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Cole Grover
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Re: Hand-digging Vernal Pools in New Jersey

Post by Cole Grover »

Interesting. Pretty cool to see it work after having observed lot of failed attempts at making an "artificial ecosystem."

I know New Jersey and the federal government both have regulations regarding stormwater pollution prevention (SWPP). Many municipalities do, too. Major silt run-offs from mis-managed construction projects can band news to local aquatic ecosystems. Did you have to acquire permits and comply with inspections, or were you given some sort of "pass" due to the nature of you project? It's also possible that the tarping, etc. you used was sufficient to satisfy the requirements of whichever environmental agency has primacy in your area/case.

Were there any wetland permitting issues you had to deal with?

Also, is there a reason you chose to revegetate using a non-native grass (i.e. Secale) rather than a native? Was it simply the speed with which the non-native would cover the ground? Availability?

Thanks,
-Cole

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cbernz
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Re: Hand-digging Vernal Pools in New Jersey

Post by cbernz »

Cole Grover wrote:Interesting. Pretty cool to see it work after having observed lot of failed attempts at making an "artificial ecosystem."

I know New Jersey and the federal government both have regulations regarding stormwater pollution prevention (SWPP). Many municipalities do, too. Major silt run-offs from mis-managed construction projects can band news to local aquatic ecosystems. Did you have to acquire permits and comply with inspections, or were you given some sort of "pass" due to the nature of you project? It's also possible that the tarping, etc. you used was sufficient to satisfy the requirements of whichever environmental agency has primacy in your area/case.

Were there any wetland permitting issues you had to deal with?

Also, is there a reason you chose to revegetate using a non-native grass (i.e. Secale) rather than a native? Was it simply the speed with which the non-native would cover the ground? Availability?

Thanks,
-Cole
Umm, yeah, about those permits... I never looked into it or really thought much about it. Certainly not on the state level. I guarantee that on the township level their biggest concern would be mosquito-borne illness, and if they were going to have me spray chemicals or treat my water to kill mosquito larvae, then I'd just as soon skip the whole project. The first season, the mosquitoes were pretty abundant. The second year they were not so bad, because of the number of tadpoles, beetles, and other predators in the water. Anyway, the pool is at least 200 feet from the nearest house. Siltation from the pool was not a concern at all, because of the small scale of the project and its distance from the stream. In reality, the biggest siltation problem in my yard probably comes from the deer trampling and eating all the understory plants. At some point, I'll fence off the woods and try to replant some native understory.

So the answer to your question is that basically I gave myself a "pass" and went ahead with the project, but I was always mindful of what I did with the fill. Oh, I should also mention that the Passaic River is one of the more polluted waterways in the area, and for years was an unmitigated dumping ground for raw sewage and industrial waste. It's gotten a lot better since then, but there's still so much going on in and around the river that I doubt anyone's really concerned with silt from small-scale building projects. But yeah, if I lived right near a pristine stream with sensitive fish populations in it, I would definitely be more mindful of permit issues.

I know of a Green Acres site with a population of state-threatened Blue-spotted Salamanders. It's right off a major highway. The state owns a frontage road about 300 feet from some vernal pools, and it uses this road to park dozens of huge DOT vehicles, which make mud and leak who-knows-what into the ecosystem. The cops patrol the area and prevent people from accessing the park (even though it's marked public access), but somehow can't do anything about the people who periodically dump garbage bags and car parts all over the place. Welcome to NJ.

As for your last question, I chose winter rye because it's an annual that will germinate in cold weather. It served its function, and was pretty much gone by the following fall. I probably could have even skipped that step, because almost as fast as the rye grew in, the invasive Japanese Stiltgrass had pretty much overwhelmed the area. The plant situation in my yard (as in much of the state) is pretty dire. I love Japan and the Japanese, but if I could wave a magic wand and make every plant with "Japanese" in front of its name disappear from my life forever, I'd be a happy person, even though I'd lose my pretty Japanese Maple. Eventually I will figure out a way of getting rid of the Stiltgrass and the Barberry, hopefully without resorting to chemicals.

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Cole Grover
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Re: Hand-digging Vernal Pools in New Jersey

Post by Cole Grover »

Right on. Thanks for the info. I appreciate the response!

-Cole

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Kelly Mc
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Re: Hand-digging Vernal Pools in New Jersey

Post by Kelly Mc »

Once apon a time in Jersey a cool Dad and his cool Kid, did some Great Work together.

Coluber Constrictor
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Re: Hand-digging Vernal Pools in New Jersey

Post by Coluber Constrictor »

Keep up the great work :beer: I have wanted to do this exact thing for a while now, but have no land to do it on. Ephemeral ponds really are magical little places.

Good luck with your wildflower meadow too, the butterflies will really appreciate it. I've been able to plant some native stuff in my parents' yard, and I see some pretty impressive bugs there now.

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cbernz
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Re: Hand-digging Vernal Pools in New Jersey

Post by cbernz »

So far, so good. The pool filled up nicely after a winter storm dumped almost 3 inches of rain:
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The deepest part of the pond was filled up to about 17 inches.

Here's what it looks like right now, frozen over:
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I spread wood chips over the exposed dirt to prevent erosion. When the ice thaws, I'll go back out and dump a whole bunch of dead leaves into the pond, to cover the bare mud at the bottom and provide nutrients and habitat for benthic organisms. I'll also dump in some logs and branches.

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Brian Hubbs
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Re: Hand-digging Vernal Pools in New Jersey

Post by Brian Hubbs »

This is awesome. Now all you need are spotted turtles.

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Zach Cava
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Re: Hand-digging Vernal Pools in New Jersey

Post by Zach Cava »

Looks great, and hopefully will inspire others to get into similar projects. Thank you for sharing!

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Fundad
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Re: Hand-digging Vernal Pools in New Jersey

Post by Fundad »

Bravo, Great work.. :thumb:

Thanks for sharing :beer:

Fundad

tkennedyfour
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Re: Hand-digging Vernal Pools in New Jersey

Post by tkennedyfour »

Looks awesome! I hope to someday take part in a project like this, definitely checking out that PDF for more info!

Thanks for the post,
-Taylor

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Tyler G
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Re: Hand-digging Vernal Pools in New Jersey

Post by Tyler G »

Awesome job man. I did something similar earlier this year and it's been a fun and successful project so far. When I moved 3 years ago my new place (which is right next to a large pond) had an old fire pit in the back yard, but it was always filling up with water when it rained so I never used it. I always found frogs and some snakes from time to time around it, so I just left it there and enjoyed the easy access to nature. Eventually it struck me to clear it out and make it into a little pond since it was always flooded anyway, and make it as appealing as possible to the wildlife.
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After I cleared it out, I saved all of the rocks and any of the wood that wasn't burnt or rotted all the way and laid it out around the pond. I salvaged as much of the tall grass as possible and replanted it, and also set up a little bird bath (with bird seed in it...). The whole thing is about 8 feet long by 6 feet wide, and I dug maybe 2 or 3 inches of dirt out of it, just to make it even all around. It was functional by the time spring rolled around, filling up and retaining water for weeks any time it rained. The center of the pond (I dug it an additional few inches - which I guess met the water table) retained water throughout the entire summer although the rest was mostly mud during dry spells.
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A few months ago I added a little roof over the bird bath and a rail - stuff for the birds to perch on and give them cover. This is what it's looking like now:
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Over the last 8-10 months this little pond has provided habitat for:
Bullfrogs
Green Frogs
Garter Snakes
a baby Northern Water Snake
Breeding Fowler's Toads
Gray Treefrogs calling in the oak tree right next to it
Pickerel Frogs hang out under the logs
Lots of cool bugs on the plants around it (I let it get over-grown from time to time)

My bird feeders see 3 species that come through on a pretty regular routine (Carolina Chickadees, Tufted Titmouse, and a woodpecker that's been out there for the past month or two - not sure on the ID) and plenty more that stop through from time to time. I've had a Heron hanging out in there and a family of Canada Geese (with babies) who thought it looked nice enough to take a mud bath in.

The project took very little work; all I really had to do was scrape enough dirt out of it so the water laid even when it rained, and decorated with natural stuff around it. Having a huge pond 10 feet away from it doesn't hurt, either. This spring I'm going to get some native plants to plant, and I'm sure I'll add more features to it as time goes on. I hope to do it on a bigger scale one day, and seeing your project helps inspire it. Good work.

Here's a few shots of my pond's visitors:
Bullfrogs hang out in there all day, every day.
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I thought this baby Musk Turtle was a muddy acorn when I was going through my dip net.
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This little dude was hiding under one of the logs near the water.
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