Backyard Swales in the Hudson Valley?

Hello Permies.  

I am new here.  I have designed a backyard swale, and I'm just not sure if it's a good idea.  I seem to change my mind every 10 seconds.  Perhaps you kind folks could lend some advice.  

Here are the facts about my site:

1/4 acre suburban lot in Beacon, NY.  Zone 6a
We get 49" of rain each year and 35" of snow each year, evenly throughout the year, except slight less in July and August.  (Wetter climate than many swale systems are designed for, from my understanding.)
The backyard has just a slight grade.  It drops about 1.5 to 2 feet over a 50 foot length.  However, the neighbor's yard (uphill from the proposed swale) has a steeper grade and would likely contribute runoff into the swale.
Soil is quite compacted and slightly clay-ey.  
I dug down about 4.5 feet to be sure I didn't hit the water table (on advice from Stefan Sobkowiak's permaculture orchard film).  I didn't hit water.  We've just melted a lot of snow over the last few weeks and the ground is not frozen, so I'd assume that this would be a high water table time (if it fluctuates).  The sub soil seems very clay-ey.  

I've got a nice chicken and annual bed rotation happening, which I really enjoy.  Now I'd like to get some fruit trees planted and have read a lot about swales as tree growing systems.  
The permanent nature of swales and trees has me a bit nervous about whether to do it or not.  

The swale would collect over ground runoff.  And I could rout some downspouts into it if necessary.  I have room for a swale width of 2 to 3 feet, and a berm with of about the same.  I want to plant fruit tree guilds on the berms.  

The swale is about 50 -60 feet in length, on contour a squiggly "C" shape - I've already marked it in the yard.  
I've attached a sketch of the plan.  The blue is the swale.  The brown is the berm.  Orange (they scanned in light brown) are approximate one foot contour lines.  Where it says vinyl fence is the highest point on my property, but the slope continues up in the yard where it says "N/F" in the bottom right of the page.  Blue arrows show rain runoff directions.  Overflow of the swale would head Northwest to the Asphalt Walk, between the house and garage toward the street.  Very minimal grade through there - I'd almost say completely flat.  

I've been on the property since August 2015 (not that long).  So far, the only time of year it seems like keeping more water on the property is a good idea would be July and August.  Yet, most every permaculture resource says the first thing we want to do is get our water harvest up.   But this might be a case of "if it ain't broke, don't fix it."

Really the questions I have are, do I want to keep more water around if we get that much rainfall and snow each year?  Will I end up with a swamp or trees with wet feet?  Would this small swale make a difference?  

I'd appreciate any advice you might have.  I have browsed the Permies forums quite a bit, as well as searched the internet far and wide, but I haven't found a lot of info for anyone who has tried this in this wet of a climate.  Point me to any relevant resources you know of.   Thanks!  Jesse

Geoff Lawton talks about the "watery wonderland" you'll get with a rain harvesting landscape.  His climate is even wetter than yours.  I think Ben Falk's situation in Vermont is more similar in climate to yours, but Ben has acreage and directs excess water to ponds and even a rice paddy.  I think in a small yard, you do risk making some areas too moist unless you specifically want to grow plants which demand more water.  It's not that swales are not meant for wet climates, it's that they may not be appropriate in every situation, where extra moisture might not be desirable.

Ben Falk's place:  https://vimeo.com/168769057

If potential water intrusion to a neighbors yard is a concern you could consider designing your swale into two parts. The higher elevation would retain water and feed into a lower swale that has been excavated and the clay replaced with asand and/or gravel so as to provide a drain into the water table for exceptional amounts of water. One advantage of this approach is the water level for the upper swale could be adjusted easily to flow less or more water into the drainage swale.

We have a small rain garden/swale in our suburban front yard in our clay, Mid-Atlantic yard that was put in by the city at little cost to us as a program to cut down on rain water flowing into the street and hence into the Cheasepeake watershed along with the pollution that it would gather on its travels. Basically they brought in sand and topsoil and used it to replace the clay which I used to build up the foundation around the house. A shallow pipe takes water directly from our gutters into the swale and even in torrential downpours it never overflows.

Another consideration you might entertain is the more traditional water barrel that could be used either in combination with a swale or on its own. I remember seeing a design for in ground water storage where an underground box is excavated and lined with a waterproof liner (I think like the rubber used on roofs) and the plastic milk crates stacked inside to proved structure and the waterproof wrap sealed up with a drain that was designed to prevent intrusion of leaves and sticks. Being shallow extraction of water from the reservoir would be bog easy, even without electricity and could be covered with a patio.

Good luck on your project regardless. Our farm is 2 hours north of you so we are neighbors! Beacon is very close to where my mother's family settled in Fishkill before the revolution and one family house still stands as a museum there, so we are very familiar with the area.

Thanks you Tyler and James.   Helpful stuff.  

I should clarify that I hadn't seen many examples of BACKYARD swales for my area.  I've seen a lot of Ben Falk's stuff online.  So awesome and inspiring, but a much bigger scale than I have.  I saw some of Geoff Lawton's stuff on Urban PC, some that he did in Sydney, which gets almost as much rain as us, but no snow.  

We are near the base of mount Beacon, so I think the city is more concerned about getting the runoff routed swiftly into the Hudson River - especially in a major rain event, without it eroding any land.    

i grew up on the river as well. my yard overlooks the river its potters clay anywhere from 4-18 inches down . do you by any chance have that thick clay layer? i have noticed my best results are with organic mater built up as apposed to depressions on contour. the way i test for this is digging a hole this time of year if its mucky and sloppy clay then its not a spot for a depression its a spot for a raised bed. regardless you are on the right track wanting to slow the water in my opinion. looking forward to seeing your progress after over a decade of a garden here this house will no longer be in family hands in the near future. i will have to live vicariously through your projects i guess.