Find out why vernal pools, fairy shrimp and woolly meadowfoam are ODOT’s golden ticket
After eight years of meticulous work, folks in our Southwest Region office completed an innovative wetland restoration project. What makes this project special is the rare and unique habitat they restored, the huge benefit it provides and the partnerships that made it successful.
A unique and special habitat
The Rogue Valley is not only beautiful but home to an uncommon geological landscape. In a protected grassland sanctuary near White City, the Agate Desert provides the ideal environment for vernal pools. Vernal pools are a unique wetland type because they are seasonal pools that fill up during the rainy season and dry up in the late spring. These extreme conditions make an ideal habitat for the threatened crustaceans known as fairy shrimp and two rare and endangered species of plants.
Fairy shrimp are hardy little creatures and special because they have developed a strategy to thrive in the harsh vernal pool environment. The lifecycle of the fairy shrimp is short but fascinating. When the pools fill with rain, eggs hatch and mature into adult shrimp that breed and lay more eggs for the next cycle. When the water dries up, the mature shrimp die but the eggs essentially lay dormant throughout the intense heat of the summer and the cycle begins again in the late fall. Adult shrimp have delicate bodies and occupy these habitats that are mostly void of predators.
“Not all the eggs hatch that dried out the season before,” said Paul Benton, ODOT environmental wetland scientist. “Many lay dormant for years before hatching. The shrimp use various strategies to survive and keep the cycle going. Some hatch right away, some will lay dormant for several years, some will only hatch in the late-season spring rains. There may be temperature or water quality ques that signal the eggs to hatch. No one knows for sure how it works, but these strategies help them persist.”
Even the rare species of plants that grow in and around the vernal pools have adapted to these conditions. In fact, only native species can survive in these very specific conditions.
“Two endangered plants, the Cook’s Lomatium and the large-flowered woolly meadowfoam, tend to flourish around the edge of the pools so in the spring when the water dries up you will see a bathtub-like ring of flowers where the water once was,” said Brad Livingston, ODOT Environmental Wetland Program coordinator.
A new strategy provides protection and ongoing dividends
Instead of mitigating small wetland projects one at a time, all the smaller wetland projects get combined into one large identified site.
“As projects come along, the mitigation site works just like a bank account and instead of spending money, you spend wetland credits,” said Benton. “This method is super-efficient because it streamlines the environmental process for the agency, saving us time and giving us confidence in project delivery. It also saves time in management and monitoring costs because we are looking at just one large site instead of five or more smaller sites scattered across the region.” ODOT took it one step further by developing Oregon’s first ever wetland and conservation mitigation bank as the vernal pool site serves as mitigation for wetlands and listed species.
The Highway 62 Corridor Solutions project was one of the biggest transportation projects in southern Oregon. Its alignment, however, disturbed a range of wetland types including vernal pools. To mitigate this impact, we needed to replace these wetlands somewhere else.
“We decided to go big with this wetland mitigation bank,” said Livingston. “We found an area next to a Nature Conservancy Preserve where it is more likely to succeed and not in the way of any future transportation plans. This mitigation project far exceeds any impact ODOT has had on the area and our restoration efforts have been so successful that we can use this bank for years to come to mitigate future project impacts.”
Agencies such as the Department of State Lands and the U.S. Army Corps of Engineers are wetland regulatory agencies who have prioritized mitigation banks as their preferred strategy because a larger site has more sustainability and is more likely to be successful. Because vernal pools are so rare, the regulatory agencies allow vernal pools to serve as wetland mitigation for all wetland types. This has allowed ODOT to develop a single mitigation bank which now can provide mitigation credits for all wetland impacts throughout most of the region.
“The reason we went so big with vernal pools is because it is such a unique opportunity,” said Livingston. “Vernal pools are the ultimate golden ticket because of its high priority listing.”
Using Partnerships to build a field of dreams
ODOT manages 196 acres of vernal pool property and contracts with local experts at the Nature Conservancy to help develop the site. Over the last eight years, Benton, along with TNC Field Ecologist Keith Perchemlides and transportation maintenance specialists from the District 8 Maintenance crews worked every summer to uncover and restore the original vernal pools on this land covered up years ago with upland soil.
To locate the original pools, Benton and his team pulled historic aerial photos of the property and looked at LiDAR data, then developed a plan.
“We went out to the spots where the vernal pools would likely be and began to slowly dig, much like an archaeologist,” said Benton. “By using this technique, we were able to uncover the old vernal pool surfaces.”
A key member of the team is Cam Patterson, a private contractor who has developed this technique over his 40+ year career restoring vernal pools.
The incredible part of unearthing and rebuilding the historic vernal pool landscape was that they were using large equipment to do it. This is where the partnership with ODOT maintenance has been so critical. The operators delicately removed a half inch of soil at a time with giant excavators while the biologist looked at each layer before directing where to dig next.
“Perhaps the greatest challenge of this kind of restoration is getting equipment operators to listen to the biologist,” said Benton. “Operators aren’t used to this type of earth moving where the final grades are driven by what the ground is telling us instead of a designed grade.”
The maintenance crews have risen to the task and excelled, none more than Wayne Scriven who has been involved in all eight years of the project. Scriven is now an expert at it. After a few years of working every summer to refine this very specific skill, he now knows exactly what to do.
“He sees the landform and knows what we are trying to accomplish,” said Benton. “He reads the ground really well and nearly got to the field of dreams state where the ground’s telling him where the mound needs to be and he just makes it happen. It is very prescriptive and slow going and takes a skilled dozier operator to do this type of work.”
“There has been a lot of work that has gone into this project and the Maintenance crew has been really supportive of our work and are a great partner,” said Benton. “To be able to pick up the phone and call Steve Stone, transportation Maintenance manager of the Central Point Maintenance Crew, with a request for help and have to him put guys on it that day or the next has been a huge part of our success.” It’s truly been a winning combination. So far, 17 projects have debited credits from the wetland bank account. In addition, the vernal pool mitigation bank project will continue to serve other projects in the area for at least another 10 years.