Is Flooding Good for Farmland?

As with most any topic, the best answer is, “It depends.” Flooding can be beneficial and also devastating. Throughout history and up to today, food is often grown on lands adjacent to the mightiest rivers, think the Nile, Tigris and Euphrates, Ganges, and Mississippi Rivers and on floodplains of the smallest creeks. Why grow food in the floodplains? It’s the soil and the water.

In early times, human and animal labor and the powerful force of gravity were the only tools for farmers to mold, shape, and sculpt the landscape to ensure the best possible growing ground. Mother Nature would provide the rains eroding the uplands just enough to loosen the sediments and soil minerals. The drainage ways, creeks, and streams would funnel fast moving sediment-laden waters rapidly downstream to the rivers’ flatlands. Gravity performed its job in the river deltas and floodplains, quickly slowing the waters, the water spreading out to the edges of the valley, dropping the nutrient-laden soils, and hence, building farmland.

2006 Flood at Full Circle Farm, Carnation (Photo courtesy of Stewardship Partners)

2006 Flood at Full Circle Farm, Carnation (Photo courtesy of Stewardship Partners)

The Nooksack, Skagit, Stillaguamish, Snoqualmie/Snohomish, Green and Puyallup Rivers are western Washington’s mightiest rivers. Each is fed from the snow slopes and nooks and crannies of the Cascade Mountain range filled by the incessant winter storms off the Pacific Ocean. As the Cascade creeks and streams release the water, it tumbles, jostles, tears, erodes, and carries new soils to feed the mighty rivers with depositions to build and augment the prime food growing lands on deltas and floodplains. Of course, not all viable farmland is found only on floodplains, as orchards, wheat and corn fields, and many row-crop truck farms are found on uplands. The upland farms, however, are more dependent on the vagaries of nature’s rainfall or man’s intentional irrigation systems than the farms located in the floodplains. More importantly uplands are much more expensive just because the land doesn’t flood! Many farmers can’t even begin to afford the cost of flood-free farm ground. 

As farming cultures advanced through the eons and became more mechanized with tractors and machinery, the farmers, often times with the governments’ help and financing, moved dirt and brought in construction materials to modify and change the forces of nature and to  control the rivers. Organizations such as diking districts, cities, county governments, and the Army Corps of Engineers built dikes, levees, seawalls, dams, and irrigation channels to control, direct, and channelize the water.

Bucolic Summer Days in the Skagit with Mt. Baker Looming in the Distance

Bucolic Summer Days in the Skagit with Mt. Baker Looming in the Distance

The Skagit River about one-hour north of Seattle, is a prime example of many of these man-made modifications. Highly fertile and productive farmland was always located at the edge of the Salish Sea in what was originally the Skagit River’s delta. The delta is now modified by levees, dikes, drainage channels, and floodgates–to protect and manage some of the most fertile and productive farmland in the world. About 35 miles upstream as the crow flies from the Skagit delta are two Puget Sound Energy dams, designed to generate hydroelectric power and to control and regulate flood flows. With warm, tropical, moisture-laden clouds pummeling the Cascade Mountains western slopes in what is classically known as a Pineapple Express during the rainy season, all of these manmade structures have modified and controlled the tempests of nature–both the influx of saltwater tides and the devastating floods from excessive rains or rapid snowmelts. In its original condition the Skagit was home and habitat for significant record salmon runs. Today the salmon runs are still the envy of many other watersheds, but are less than when the river was in an unadulterated state. Now, the land in the Skagit watershed grows potatoes, berries, row crops, dairy, tulips and seed crops—including being home to 95% of the beet crop in the world, carries significant salmon runs, and is home to more than 110,000 people. The people in Skagit County have created a structure through the Farm, Fish, and Flood Initiative to debate, analyze and evaluate these competing environment, farming and built communities issues. All of these issues are tough and not easy to resolve, as they are all important and impact many livelihoods.

The State of Washington also evaluates impacts from flood events. According to the 2013 Washington State Enhanced Hazard Mitigation Plan, the lower Skagit around Mt. Vernon is one of the highest risk areas for flooding. As said in the same document, despite the fact that the environment–farmland, habitat, and undeveloped lands–are impacted by flooding, it does not merit the same attention that people, developed property and the economy receives from the effects of flood events. Still farmers often do take the brunt of flooding, as it is land that is readily available to accommodate flood waters. Floods are inevitable, but the question still remains, is flooding good for farmland?

Flooding and Farmers

Katahdin Sheep at Ninety FarmsNever tell Farmer Linda Neunzig, that flooding is good for farmers. Linda farms 50 acres adjacent to the Stillaguamish River, just west of the City of Arlington, WA, at Ninety Farms. She  raises Katahdin lambs for export around the world as breeding stock and to be sold to local high-end restaurants such as terra plata in Seattle’s Capitol Hill neighborhood. For Linda, her farm, being located on the inside of one of the “Stilli’s” many oxbows, can have devastating flood effects from which there is lots of cleanup and economic loss. “The economic impact from cleaning up the river carried debris, replacing the lost and damaged crops, and removing the excessive silt deposits can be a severe economic and time impact on any farmer, including myself,” says Linda. With each upcoming winter flood season, Linda has to always be prepared to load her 125 breeding ewes into a truck to get them to higher ground,  out of the way of potentially ravaging flood. After any impactful storm, it’s also absolutely necessary to remove debris that has been carried downstream by the flood. Any thick layers of sediment on the fields is either tilled back into the ground or overseeded to ensure that spring grasses can grow again. Flooding for Linda is not an economic or farm benefit.

Summer Radishes and Carrots

Summer Radishes and Carrots

Local Roots Farm, a local truck farm, grows multiple row crops including cabbage, rutabaga, tomatoes, kales, beans, and more in the Snoqualmie Valley near Duvall, WA. They sell their product through their thriving Community Supported Agriculture (“CSA”) business and sell to local restaurants and at several local farmers markets, too. Flooding is not as significant an issue for Siri Erickson-Brown, Local Roots Farm owner and farmer. Specifically, Siri says, “Our farm is located on a reach of the Snoqualmie River which does not have highly erosive flows, but rather the river deposits just the right amount of silt and sediments during the winter months to augment our farm’s soil rather than impact it negatively.” Further, Siri explains, “Being in the Snoqualmie River’s floodplain allows us to have minimal irrigation concerns through the dry summer months. The soils hold the moisture well, allowing us to grow a wide variety of crops.” Siri does however, agree that the flood impacts on the local roads can be terrible. Flooding closes bridges, diverts traffic, and can cause significant cleanup costs and time for many people.

Floods are a constant concern during Western Washington’s rainy season and are often not beneficial to a farmer. Depending on the intensity of a storm–how much water is held in the clouds, the existing snowpack in the mountains, and the ambient air temperatures in both the lowlands and in the mountains, flood impacts to farmland can vary greatly. It’s important to remember that just because the urban legends says that floods benefit farmland, it’s best to ask the farmer. The farmer knows what’s best for their farm.

Kathryn Gardow, P.E., is a local food advocate, land use expert and owner of Gardow Consulting, LLC, an organization dedicated to providing multidisciplinary solutions to building sustainable communities. Kathryn has expertise in project management, planning, farmland conservation, and civil engineering, with an emphasis on creating communities that include food production. Kathryn is a Washington Sustainable Food and Farming Network board member and on the Urban Land Institute–Northwest District Council’s Center for Sustainable Leadership planning team. Kathryn’s blog muses on ways to create a more sustainable world and good food!

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Flood Info 101: Flood Season is Here

Despite a dry month, October 1st is the start of the regulated flood season in King County, Washington which ranks 13th out of 39 counties in agricultural revenue and is home to Seattle, the State’s largest city. From almost 1,800 farms, $127 million is earned growing food, fiber, and animal feed, even though the County houses almost one-third of the State’s 6.7 million people. Combined Snohomish, King, Pierce and Thurston counties generate $435 million in agricultural revenue from over 6,000 farms.

Remnants of the November 2006 Flood

Remnants of the November 2006 Flood

It has been almost 7 years since the November 2006 election day 100-year storm.  In 60 degree weather, Monday, November 6, 2006, 3.29 inches of rain fell at Sea-Tac airport. Concurrently, the warm, tropical, moisture-laden clouds, also known as a Pineapple Express, pummeled the Cascade Mountain’s western facing slopes about 60 miles east of Seattle, melting newly fallen snow and sending torrents of water into the lowlands. The flat Snoqualmie Valley received more than 32 million gallons per minute (71,800 cubic feet per second [c.f.s.]) of turbid, rapid-flowing water carrying anything not secured.

2006 Flood at Full Circle Farm, Carnation (Photo courtesy of Stewardship Partners)

2006 Flood at Full Circle Farm, Carnation (Photo courtesy of Stewardship Partners)

Only two years and two months later, in January 2009, another 100-year Pineapple Express storm inundated the Snoqualmie Valley with an amplified repeat performance surging 37 million gallons per minute (82,900 c.f.s.) downstream reaching an unprecedented flood stage of 62.21 feet near Carnation, which was almost one foot higher than the 2006 record of 61.28 feet.

Despite the misnomer that a 100-year storm happens only every 100-years, in scientific terms it is the storm that has a 1% probability of happening in any particular year.  With probability theory, there is really a 63.4% chance of a 100-year storm occurring in each wet season. Consequently, the chances of another devastating flood happening is much greater than it not occurring.

Thankfully, many western Washington counties have heeded Mother Nature’s wrath and now provide tools for farmers and homeowners to be warned of upcoming fury from exceptional weather systems.

King County’s Flood Alert System

King County has designed a message alert system to send texts, e-mails or phone calls to those who have signed up with the free King County Flood Alerts system for timely information on flood events. Notification of 3-different flood stages on the Cedar, Green, Tolt, and White Rivers, Issaquah Creek and for the Snoqualmie Basin are sent.  The first notification level is Phase 2 indicating minor flooding in some areas. The Phase 3 message designates moderate flooding, while a Phase 4 notice signifies that there will be road closures and major impacts from the deluge. These alerts show the level of storm impact and are beneficial even for those people not directly in harm’s way, since excessive rainfall can impact travel plans and localized flooding, too.

Floodzilla's Snoqualmie Stream Flow, Nov. 19, 2013

Floodzilla’s Snoqualmie Stream Flow, Nov. 19, 2013

Another informative Snoqualmie River tool is Floodzilla, created by a computer geek that wanted real time information on predicting whether there will be a noteworthy flood event.  He didn’t want to receive notifications as each flood phase was reached, since that could be in the middle of the night.  Rather he wanted to see what the National Oceanic & Atmospheric Administration (NOAA) computer model predicted for future flood potential.  His model can forecast flood elevations up to three days ahead based on anticipated rainfall, which gives homeowners time to prepare for a flood.

As shown on the above graph, the Snoqualmie River is expected to reach minor flood stage at Carnation (red line), mid-day Tuesday, November 19th and then begin to recede. The forecast is predicting additional precipitation late Wednesday or early Thursday morning, which will slightly increase the river’s flow, but not reach flood stage.

Thurston County’s Emergency Management System

Anticipated Chehalis River Levels on January 11, 2014

Anticipated Chehalis River Levels on January 11, 2014

Thurston County Emergency Management has the most usable interface for flood monitoring for the layperson for the Black, Chehalis, Deschutes, Nisqually and Skookumchuck Rivers.  The two pieces of information on the Emergency Management website are 1) a graph of the river water elevation for a full week, including the previous 3 days, the next 3 days and today and 2) a table depicting the different flood elevations with the potential impacts from too much water in the drainage basin. On the graph above, the amateur flood watcher can see whether the water elevation is expected to continue to rise on the Chehalis River at Grand Mound, or when the flood stage is expected to start falling.  On this January 11, 2014 graph, the flow and water rates are expected to rise through the weekend with the weekend storm, but no significant flooding is currently expected.

Chehalis River Historic Flood Stages

Chehalis River Historic Flood Stages

At the same time, as shown on the table to the right, there are dates of past flood events with the expected damage at each flood elevation which can help homeowners anticipate whether they should consider evacuating to higher ground or not. With the expected 11.5 foot water elevation later this weekend, the river is not anticipated to reach the 12.2 foot elevation when minor flooding begins with banks overflowing into nearby fields and over a few roads.  It will be interesting to monitor the online real-time graph throughout the weekend to see if there will be additional flood concerns. Minor fluctuations in temperature in the mountains, where the precipitation changes from snow to rain or the intensity of the lowland storm changes could change the current predictions.

Pierce County’s Flood Alert and Mapping System

Pierce County Rivers Flood Forecast

Pierce County Rivers Flood Forecast

The Pierce County Alert System has a flood alert system where the County will e-mail, text or phone you with critical information about the status of specific County rivers.  More importantly, the County has a “quick look” flood status map, called the Pierce County Flood Monitor, which expeditiously depicts where flooding is occurring.  This map is real time, but does not give any indication of anticipated future flood flows.

Snohomish County’s Flood Mapping System

Oct. 29, 2013 Snohomish County Flood Map

Oct. 29, 2013 Snohomish County Flood Map

Snohomish County Flood Warning System has a great map that is updated every 15 minutes with flood information at key locations along major County rivers.  Depending on the color of the square on the map, a quick observation of the flood status can be determined.  A green square signifies normal flow, a yellow square depicts a Phase 2 flood elevation, which has minimal impacts, Phase 3 (orange) and Phase 4 (red) signify increasing flood concerns. Clicking on a square pops up a new window where the river elevation in relation to the flood phases can be compared.

Prepare Yourself

As we head into flood season it is important to find out what information is available in your County and sign-up for alerts or “bookmark” your river resource, so you can take precautions to protect your livelihood and home.  These are amazing tools our government have created to help us prepare for flooding and it is important to take advantage of them.  With a 63% chance of a 100-year storm event any given wet season, it is critical to be prepared.

Kathryn Gardow, P.E., is a local food advocate, land use expert and principal of Gardow Consulting, an organization dedicated to providing multidisciplinary solutions to building sustainable communities.  Kathryn has expertise in project management, planning, and civil engineering, with an emphasis on creating communities that include local food production.  

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Vulnerability of Agricultural: Kent Valley

Foodies and agricultural preservationists reminisce the vast acres of lush agricultural soils now covered by asphalt, shopping malls, aerospace giants, and warehouses in western Washington’s Kent Valley.

Historic Kent Valley

For generations, the Kent Valley, with its meandering Green River, was home to a robust agricultural community feeding the  burgeoning Seattle metropolitan area.  What is less remembered or romanticized are the ferocious floods that used to plague the valley.  Dave Sprau historian for the White River Valley Museum, writes that floods were expected to overflow the Green River banks “nearly every winter.”  These were not just nuisance floods, but significant floods that left two to three feet of water running through living rooms, while the waterway momentarily considered new paths as rivers are wanton to do.

Old Kent Valley Barn

Old Kent Valley Barn

Today, the answer to these devastating floods would be to elevate or relocate an existing home out of the flood’s fury.  Any future development would be restricted by strict building codes requiring flood doors to allow water passage beneath an elevated home or to transfer the legal right to develop flood prone property to land more suitable for higher density development, usually in a neighboring city.

Accommodating inundation waters was not a solution for our predecessors, as farmers and landowners were looking to decrease the annual cleanup process from continued flood devastation.  As a result beginning in 1926, a new group the Associated Improvement Club of South King County with its subgroup “The Need for Flood Control in our Valley” began to look for solutions to control the river.

Kent Valley Heritage Farm adjacent to suburban development.

Kent Valley Heritage Farm adjacent to suburban development.

The Great Depression and World War II intervened and delayed significant progress on Green River flood solutions.  However, by 1955, a location at the base of Eagle Gorge on the Green River and a congressional appropriation accelerated  erection of the earthen dam now known as the Howard A. Hansen Dam, named after the man that worked tirelessly to ensure its completion.  As construction commenced, the Green River gave one last punch in 1959 with a flood that cost upwards of $35 million in today’s dollars.  By 1962, the Green River was officially tamed and what once was a water-logged, soggy, flood-prone farming valley looked highly desirable for urban/suburban, commercial (Southcenter Mall) and industrial (Boeing) development, since it was flat, dry, and easy to access.

American Farmland Trust in its January 2012 publication entitled, Losing Ground:  Farmland Protection in the Puget Sound Region states that King County lost 162 square miles of farmland between 1950 and 2007.  The lower Green River basin between Auburn and Tukwila, which corresponds to the acreage of the cities of Kirkland, Bellevue, and Redmond combined,  is approximately 1/3 of those lost farmland acres.

Recent Flood Threats in the Kent Valley

During the original dam design in 1949, concern was expressed about a 10,000 year old geologic formation that was created when a mountainside slid into the Green River proposed for the right abutment.  At the time, confident with 10,000 years of geological solidification, designers thought the failure risk was minimal and developed a dam design that further decreased any threat.

Temporary levee reinforcement on top of existing levee

Temporary levee reinforcement on top of existing levee

Fast forward to 2009, and an inspection of the Howard A. Hansen structure after a significant winter storm revealed seepage through the right river abutment  and dam fragility.  Local and state governments scrambled to reduce the risk of catastrophic failure, by reducing the water held behind the barrier, developing escape routes and warnings, and temporarily raising levees in the flat former farmlands to mitigate any impacts from a possible deluge.  Concurrently, engineers worked fervently developing a solution for dam integrity.

Why was it so compelling that the dam be fixed?  What was at risk besides loss of life, limb and property (as if that was not enough), if the structure failed?  Why do we work so hard to protect human built features from the potential ravishing destruction that nature or man’s failing could bring?  Farm advocates were breathlessly watching to see if this was a rare opportunity to slowly bring the valley back to its agricultural roots.

Kent Valley is Washington’s Economic Engine

What is critical to know is that elected officials, business people, and our state economy could not tolerate a catastrophic dam failure.  To evaluate the importance of the Howard A. Hansen Dam, Washington State Department of Commerce in cooperation with King County prepared an April 2010 analysis of the Economic and Revenue Impacts of Potential Flooding in the Green River Valley and found that the Valley’s economic impact on the State’s economy is staggering:

  • 1/8 or 12% of Washington’s Gross State Product equaling $107 million per day resides in the valley;
  • About 100,000 jobs or approximately 8% of all jobs in King County are found in the inundation area;
  • $112 million in annual property tax is collected on real estate worth $10 billion in taxable value; and
  • Approximately $100 million in annual Business and Occupation tax (10% of the current legislative biennium shortfall) is paid by valley businesses to the State’s coffers.
Kent Valley trucking business

Kent Valley trucking business

Crisis averted.  As anticipated, an engineering solution was found and completed by the start of the 2011-2012 winter wet season to stabilize the abutment thereby substantially decreasing the odds of any major flood event in the valley.

Will Kent Valley ever revert to its agricultural roots?  Probably not.  Will other western Washington valleys be able to maintain their agricultural economies?  Maybe or maybe not.  Some issues to ensure long-term agricultural production are out of our local control such as national food corporation policies, prices of products from international and domestic markets, and impacts from climate change.  These issues we can influence but most likely cannot easily change.

However, there are issues over which we have power to affect our local food economy.  To effect that influence, it takes political will and a community dedicated to maintaining a vibrant agriculture economy, by farming food production lands, removing development rights from rural lands, maintaining farm animal veterinarians, feed stores, and other agricultural infrastructure, creating land use regulations kind to growing food, and developing solutions to adapt to climate and market change.  We can have western Washington locally grown food provided we continue to work, advocate, and support it.

Kathryn Gardow, P.E., local food advocate, a land use expert and owner of Gardow Consulting, an organization dedicated to providing multidisciplinary solutions to building sustainable communities.   Kathryn has expertise in project management, planning, and civil engineering, with an emphasis on creating communities that include food production.   Kathryn’s blog will muse on ways to create a more sustainable world.

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