swales water collection in PNW

I find swails and water collection exciting. There is a lot of talk of keeping water on your land for as long as possible. My question is how does that fit in here where we have a dry season and a rainy season and clay soils that when saturated can become unstable (landslides/mudslides). Is the PNW the exception to this rule?

Thanks,
Carmela

Hi Carmela,

Naturally you can have a proper dam like structure where you can store the rainy water and away from sunlight. You can have such storage facilities that don't allow water to evaporate and through pipes you can use that water in dry season to wet your ground.

Thank you Joseph. Can you point me to water resource information specifically for the Pacific Northwest?

I have started collecting some 'programmatic level' information on the following two pages.

https://salishsearestoration.org/wiki/Agricultural_water_management
https://salishsearestoration.org/wiki/Surface_water_havesting_for_irrigation

There is not single fount of knowledge that I am aware of. You have glacial landscape and older landscapes. PNW can alternately include or exclude the Columbia plateau. You have Two to Four states and hundreds of counties. You have residential vs. industrial applications. There are urban and rural applications. In some locations you probably do have slope stability issues, but not in all situations. You have 150 years of water rights conflict and laws combined with wetland regulation. You have a regional push for 'rain gardening'.

I might be able to direct you a little if you could provide more info.

Carmela - have you read Brad Lancaster's books Rainwater Harvesting for Drylands and Beyond - Vols. 1-2? Volume 1 is an introduction to the practice of rainwater harvesting. Volume 2 is all about earthworks and when to use which kind.

The PNW is NOT the exception - there are TONS of good examples of water harvesting in the PNW. Check out the following:

Green Infrastructure Case Studies: One section of this webinar is lead by a guy from Portland

This is an image of street runoff being harvested in streetside infiltration basins (a swale-ish type water harvesting technique) in Seattle. There are more pics HERE - many are from the PNW.

Hello Paul and Jennifer. Thank you for your replies.

I am located ten minutes west of Longview, WA. There are rivers that run into the Columbia River along its Northern side. I guess they would be considered foot hills. Not quite as far as the coastal range. Route 4 runs along the northern side of the columbia. I live uphill from there. The soil here is clay and there have been slides along route 4 in the winter/rainy season. Since I am 5 miles or so from 4, I am not worried about landslides happening for no reason near my home.

There is so much rain in the winter and so little in the summer, that rain barrels seem silly to me. Within a week of winter rains they would be overflowing. It is a wonderful thing for other places I've lived, just not here.

But I like the idea of having swails to water the trees during the dry months. I am just not sure what it would do in the winter.

Thanks for helping me.

Carmela - do you know the degree of slope on your property and those upstream from you?

Usually swales are only recommended for slopes up to 17 degrees, any steeper than that and it is best to plant it out in hardy natives to stabilize the slope. Net and pan designs may also work on steeper slopes.

If you are really concerned about your situation - I would talk to your Ag Ext agent or geologist to see what they say. Mostly swales slow and spread water and are tree growing systems. In most cases I would think that this would stabilize your soils more than having water rush across it. However certain soils may be problematic.

Again, reading Brad's volume 2 below will give you more insight.

I live in Seattle and I've never felt that swales would be useful for me. The reason being that I never have any water runoff, even in the heaviest winter rains, so there is no need to try and restrict the flow of water. It all soaks into the soil already. During the dry months, I only need to dig 2 or three feet down to find moist soil, so once trees are established, they should not need any water. Instead of swales, I use hugelkulture mounds to make sure that shallow rooted annuals have access to moist soil year round. I do employ rain barrels for watering new trees and my vegetable beds. I let them drain out each fall (to avoid the possibility of freezing damage) and only fill them back up starting in March/April once the chance of hard frosts are gone. For my urban garden, I only need about 250 gallons to get through the dry summer months.

One thing you can use rain barrels for is to redirect the flow of water to places that aren't getting wet even when it rains. I have a spruce tree that is death to all that is under it. My closest barrel has a drip hose that circles all of my shrubs that are under the tree. Every time it rains that area now gets a slow watering that lasts a few days. It does overflow almost immediately, but I'm setting up a French drain in hopes of feeding many a thirsty plant along the way. I've killed off a few shrubs under there by not watering, but now I have three huckleberries doing well with plenty of moisture to go around for the wintergreen and lingonberries I plan on putting next to them.

No experience with swales, though, sorry

Thank you all for taking the time to comment, I appreciate that.


I definitely want to talk to a geologist about this. I am taking the Master Gardener class now and have access to WSU extension. Because there are so many very different areas in the PNW it is hard to get information specific to my own property or anyones specific property. I will be doing a lot more observation before trying anything.

Tom OHern wrote:I live in Seattle and I've never felt that swales would be useful for me. The reason being that I never have any water runoff, even in the heaviest winter rains, so there is no need to try and restrict the flow of water. It all soaks into the soil already. During the dry months, I only need to dig 2 or three feet down to find moist soil, so once trees are established, they should not need any water. Instead of swales, I use hugelkulture mounds to make sure that shallow rooted annuals have access to moist soil year round. I do employ rain barrels for watering new trees and my vegetable beds. I let them drain out each fall (to avoid the possibility of freezing damage) and only fill them back up starting in March/April once the chance of hard frosts are gone. For my urban garden, I only need about 250 gallons to get through the dry summer months.

The difference is climate, climate, climate! What is appropriate for one climate might be abysmal for another. You live in a HUMID climate - therefore swales might not be the best technology to employ. On the other hand hugelkultur would be awesome there.

Using aboveground hugelkultur in the hot desert (dryland) is a bad idea (more surface exposure to EXTREME evaporation, sheds limited water, and so forth). Swales, infiltration basins,- are FANTASTIC for drylands. Another example of a horrible permaculture application in hot, dry deserts are herb spirals - they are the "spirals of death" in Phoenix.

Jennifer Wadsworth wrote:The difference is climate, climate, climate! What is appropriate for one climate might be abysmal for another. You live in a HUMID climate - therefore swales might not be the best technology to employ. On the other hand hugelkultur would be awesome there.

Using aboveground hugelkultur in the hot desert (dryland) is a bad idea (more surface exposure to EXTREME evaporation, sheds limited water, and so forth). Swales, infiltration basins,- are FANTASTIC for drylands. Another example of a horrible permaculture application in hot, dry deserts are herb spirals - they are the "spirals of death" in Phoenix.

Right, but Carmela was specifically asking about the Pacific NW. In Longview, she gets nearly the exact same marine layer that I get in Seattle, gets the same amount of rain, and about the same temperature range. Longview is not a dryland. So I thought my experiences were actually quite appropriate.

My mistake - I thought she was on the "dry side" near the Columbia river!

I'm sorry I guess I should verify, I am about an hour from the Pacific coast. The Columbia is a very loooong river. It goes from eastern to western WA, two very different climates. The temperatures are also very effected by elevation. It is much colder at my home than in Longview, because Longview is in the valley.

So I am getting some reassurance to what I have been questioning and debating in my mind.

"Permaculture is different from place to place and will have different techniques, for different areas and communities"

Most of the information I have been intrigued with was located in Australia. Can I assume they have little water to work with? Amazing stuff though. I just bought Gaia's Garden which is supposed to address things in the NW. It should be interesting.

I Love the Net and Pan idea. Thanks Jennifer.

I'd agree that 55 gal drums are very inefficient. Surface storage (pond) is far more efficient if you have the land. If you actually have clay, that provides an advantage in developing a pond.

Understanding your local hydrology is a big deal... naturalized plant community composition can indicate the kind of water situation you are in. Digging holes can be useful too if you know what to look for. In our climate a south facing slope might get bone dry in summer, in another situation you might have perennial wetlands. Managing water up slope by putting it in the soil could increase water in soil and prolong the time before the summer dry down, if you have a dry down.

Then there is storage for irrigation, which is a different kind of technology although your swales could be used to collect and concentrate water at a storage, with overflow being used to hydrate a slope. I'd start with Conservation District staff, before hiring a geologist.. you'd want someone who can read soil water regime based on plant community composition.

The "principles" still apply, although the technology differs. In our climate we think about summer water, but we also think about catching and storing heat to extend our season and to keep southern European herbs and crops happy.

Alas, there is no replacement for site observation, and learning your naturalized species... in my opinion the WSU master gardeners classes don't teach enough ecosystem science.

Thanks Paul, for your response. I agree that the WSU MG class doesn't teach everything I need, but it is a start. And I really need all the info because that is the field I want to work in, and I find I don't know diddly. I am getting my feet wet so to speak. I am also doing an online permaculture class. I will probably need even more training after that. But really, that is what I want to do. I hope I have the ability to retain all the information I am reading and learning about.

I certainly didn't mean to say that MG training isn't valuable... AND its a great network. Just suggesting to compliment it with some ecological studies. Congratulations on your enthusiasm.

I was agreeing with you Paul. Is ecological studies a college course?

Usually ecology isn't taught until college level. It should be taught in grade school, and elements of ecology are embedded in the current WA state science standards.

Here's one of the books I read in school thats heavy on the assembly and structure of communities... Whittaker was a vegetation ecologist.
http://www.amazon.com/Communities-Ecosystems-R-H-Whittaker/dp/0024273902
It can be heavy weather if you are not used to technical writing.

This is one of my favorite... for extreme geeking, but it really is a seminal work in vegetation ecology--I have a library card for my local university and can get things on interlibrary loan.
http://www.amazon.com/Strategies-Vegetation-Processes-Ecosystem-Properties/dp/047085040X

Wandering far from swales... although a swale is useful because it can alter the environment which controls plant community dynamics. I believe that there are many good applications of swales in our region. The one risk is that they concentrate water, which could turn into an gully if not managed in the wrong situation. Once you get water in a swale you kind of become responsible for it...

Thanks Paul. I have a lot to learn. Wish me luck.

There are some locally relevant publications about water infiltration by WSU--focused on water quality and catering to mainstream landscape design aesthetics or capital project specifications... but interesting all the same. LID is an entry point for permaculture that has been poorly developed.

http://www.wastormwatercenter.org/low-impact/

I suspect that grey water use may be more critical in settled areas, because it occurs during our dry season and doesn't require storage.

http://www.doh.wa.gov/CommunityandEnvironment/WastewaterManagement/GreywaterReuse.aspx