Aspect Teams with Ecology on Innovative Conservation Effort

In a recent post, the Department of Ecology celebrated a successful pilot project with the Auvil Fruit Company in Vantage, WA. The project created two water banks and helped the orchard reduce their water demand by 50%. Aspect partnered with Ecology on the water rights permitting as well as the bank development efforts, but it was an innovative strategy developed by Auvil that led to this water-saving achievement.

Shade cloth installed at Auvil Fruit Company.

The solution was to cover Auvil’s orchards with shade cloth, which has multiple water savings, worker safety, and fruit quality benefits. Aspect and Ecology used two high-tech weather stations to monitor water loss: one in the area of the orchard covered by shade cloth, and one in an adjacent, uncovered area. According to Ecology, the effectiveness of the shade cloth was striking:

We found that shade cloth improved a number of growing conditions. The coverage greatly increased relative humidity, drastically reduced wind speed, stabilized soil moisture, and cooled the air temperature. Combined, all these changes now help Auvil use much less water to produce fruit. 

A weather station positioned beneath shade cloth at Auvil Fruit Company. 

The shade cloth was so effective that Auvil was able to remove windbreaks made of water-hungry poplar trees. The study also led to other water-saving strategies, such as installing soil moisture monitors and replacing overhead sprinklers with a drip system that delivers water directly to the root zone of the trees. Both of these systems communicate with one another to regulate water in real time. Water savings from the project are being used to reduce drought risk on Auvil’s interruptible water rights, and for instream flow benefit for fish. Auvil continues to be a leader and innovator in irrigation practices and Aspect’s permitting and technical skillset is making the most of these water savings.

For more details, check out Ecology’s website!

Aspect’s Dan Haller Weighs in on Water for Washington’s French-Fry Boomtown

Aspect’s Dan Haller was recently quoted in a Washington Post story about Othello, central Washington’s self-proclaimed french-fry “boomtown.” As climate change has impacted the potato business in other parts of the country, Othello has become an industry leader, but the key to sustaining this success going forward will be water.

Groundwater supply concerns have been in the news this summer (notably in this comprehensive New York Times article). Only a few years ago, Othello’s water future seemed in doubt, as the city faced decreasing yields from its wells. Aspect was brought in to evaluate the City’s well yield and determine the causes of declining groundwater supplies. Working with the City, the Washington State Department of Ecology, Office of Columbia River, and the US Bureau of Reclamation (BOR), Aspect helped develop an Aquifer Storage and Recovery (ASR) program that would support long-term growth and provide stable water supplies. The ASR program, which was first tested in 2021, operates by diverting and treating canal water to drinking water standards, then introducing (recharging) that water to the declining aquifer using existing wells. This artificially recharged and stored water combats the declining groundwater issues and can be later recovered by the City for municipal supply.

This work has been vital to Othello’s success, but as Dan points out in the Post article, the well system that farmers rely on was only ever supposed to be a temporary solution. Othello’s use of BOR canal supplies is a step towards the original vision for primary water use in the region: transitioning away from groundwater and connecting to the Columbia Basin Project, a government-funded program that stores Snake and Columbia river supplies. As Othello’s wells begin to run dry, this water will be critical to the town’s survival. The good news is there’s plenty of supply to be had; according to the Post article, the Columbia has only been tapped for 3 percent of its available water flow. Building out this infrastructure will be essential for Othello’s continued reign at the top of the french-fry world.

Perspectives on Stormwater Design and Climate Change in the Pacific Northwest

During the 2022 NEBC Stormwater Conference, which focused on emerging stormwater practices in the Pacific Northwest, a city engineer asked if the next update for Western Washington’s Hydrology Model (WWHM) will consider global warming factors. Climate change has been a prominent topic of conversation in the stormwater world recently, prompting industry professionals across all levels to ask similar questions in how tools like WWHM will accurately model future conditions so stormwater designs effectively protect water quality, communities, and habitat.

Floodwaters covered Iowa Street in Bellingham after historic rainfall in November 2021. (Image Credit: City of Bellingham)

Stormwater engineers design and size facilities using past hydrologic event models and observations – for example, western Washington uses precipitation records starting in 1948 through water year 2009 to estimate total rainfall and peak events. While this calculation method was suitable in the past, the impact on stormwater runoff due to more recent changes in precipitation and air temperature suggest that drainage infrastructure designed to manage storms based on historical data may be undersized for future storm scenarios.

According to the April 2022 Stormwater University “Climate Change Impacts to Stormwater” webinar led by Clear Creek Solutions, Inc.’s co-founder Doug Beyerlein, engineers should consider the following factors when calculating stormwater runoff in order to effectively design for future climate conditions: (1) expected changes in rainfall intensity, frequency, and duration, and (2) expected changes in evaporation and evapotranspiration. Anticipating future climate conditions at the design phase will help reduce the risk of unmitigated stormwater causing flooding, erosion, and threatening the health of aquatic species and their habitat.

Stormwater in Washington State

Stormwater management is heavily scrutinized in Washington state. The state helped jump-start the nation’s development of municipal stormwater permit programs in the 1990s and continues to be at the forefront of modern stormwater management approaches. The Washington State Department of Ecology (Ecology) issues water quality permits to cities, counties, and the state’s department of transportation (WSDOT) to ensure that stormwater runoff is being regulated and managed. These public agencies are then responsible for making sure that projects comply with permit requirements through the development and enforcement of flow control and stormwater treatment standards. Stormwater experts routinely use hydrologic models (such as WWHM) to help permit applicants and public agencies monitor stormwater conditions and forecast how stormwater will behave in the future.

Current Stormwater Calculation Methods in Washington State

From a stormwater perspective, Washington state is a tale of two lands. Western Washington (defined, regionally, as land west of the crest of the Cascade mountains) gets annual precipitation between 30 and 200 inches per year depending on location. Within this area is the Puget Sound region, home of the state’s densest population and urbanization. It receives a lot of rainfall, thus impacting runoff and stormwater management codes that influence water quality in receiving waters like the Puget Sound. Eastern Washington, the state’s more arid region, receives from less than 10 to 60 inches per year depending on location.

Washington State Annual Precipitation Map. (Image Credit: Washington State Department of Commerce)

Due to the unique climate and rainfall pattern differences between western and eastern Washington, two separate stormwater design manuals were developed for each region outlining different stormwater calculation methods (i.e., continuous simulation (applying to western WA) vs. single-event hydrology (applying to eastern WA)). Analysis of precipitation data and patterns within Washington define these two methods:

Click to Enlarge Summary of Commonly Used Hydrologic Analysis Methods and Software in Washington State

  1. Rainfall in western Washington often occurs over longer (multi-day) time frames and with relatively moderate intensities compared to eastern Washington. To accurately model and compare pre and post development runoff, it is important to account for the influence of preceding storm events and longer durations of continuous precipitation. Therefore, continuous simulation modeling is required for designing flow-based stormwater quality treatment systems and flow control systems in western Washington. Conveyance systems and some erosion and sediment control systems in western Washington can be sized using either continuous or single-event modeling.  

  2. Rainfall in eastern Washington usually occurs in shorter (often under 1 day) time frames and with relatively high intensities (like during a thunderstorm) compared to western Washington. Therefore, single-event modelling is used to size all stormwater quality treatment systems and flow control systems in eastern Washington. Conveyance systems and erosion and sediment control systems in eastern Washington are typically sized using single-event modeling.

Current Challenges to Adding Climate Change Assumptions to Stormwater Design

The design of our current drainage systems is often based on a traditional assumption that storm events are static or unchanging (also referred to, statistically speaking, as ‘stationarity’ where assumptions for future events are based on past data). However, recent studies conducted by the University of Washington Climate Impacts Group (UW CIG) indicate that storms are expected to become more severe with climate change. These projected changes in extreme precipitation in the Pacific Northwest due to a changing climate can be visualized using UW CIG’s online tool, as shown below. The example here shows that a 6-hour-long, 25-year storm event in Seattle will likely increase in intensity by 27 percent by the 2080s relative to the 1990s, assuming a high greenhouse gas scenario.

This tool provides extreme precipitation projections as a function of decade, duration, and frequency.

In order to accurately capture changes in heavy rainfall events, engineers may consider the projected changes in extreme precipitation for single-event modeling. For use in a continuous stormwater simulation like WWHM, engineers may need to incorporate the climate model projections that have been bias-corrected to match the statistics of a particular rain gauge. Click here for hydrologist Jeff Burkey’s presentation about possible impacts to King County’s stormwater design standards from projected increases in storm sizes due to climate change.

What’s Next for Stormwater Prediction Methods in Washington State?

Engineers attempting to design conveyance, treatment, and flow control systems to account for future conditions are currently stuck in a gray area. With climate change, the assumption of stationarity and exclusive reliance on historical observations for estimating future conditions is questionable.

While updates to continuous and single-event modeling techniques can be implemented using UW CIG’s regional climate model projections, software developers and public jurisdictions have limited resources and funding to quickly do so. Therefore, the current pace of change will likely continue to rely on public agencies (like Ecology and King County) to update guidance for stormwater design manuals, evaluate the capacity of their existing infrastructures to focus on locations to prioritize needed upgrades, and find ways to optimize the effects of retrofit facilities to help mitigate climate change impacts to stormwater.

Contact Stormwater Engineer Cleo Pineda to learn more.

Dan Haller Speaking on the Policy Implications of Climate Change on Water Supply Management, January 26th

Aspect’s Principal Water Resource Engineer, Dan Haller, will be discussing climate impacts to water on January 26th in Stevenson, Washington.  As future food production and processing systems in the region are expected to be challenged by water supply, the conference aims to create a dialogue among the communities that use and value the regions water supply and water quality. Dan will join a group of water resource experts to discuss policy implications of climate change on water supply management. Learn more about projected climate impacts on water accessibility in the Pacific Northwest and the sustainable management decisions HERE.