A combination of sediment and invasive plant species have plagued farm drainage ditches in the Valley for years, but with the help of King County’s Agricultural Drainage Assistance Program, farmlands are getting the maintenance they need.

On Wednesday, Sept. 7, work began on the restoration of a drainage ditch at Goose and Gander Farm in Carnation. The farm, purchased by Meredith Molli and Patrick McGlothlin in January of 2015, had a history of drainage problems including a recent deposit of sediment that caused water to flow onto the field.

“Because the Valley walls are somewhat steep, there are a lot of these alluvial deposits that come down the hillside and fill in the ditches which need to be maintained on a schedule to keep them from becoming so clogged that they don’t actually convey water,” Molli said.

“In this particular situation we had a really big deposit that caused a lot of the water coming off the hillside to skip the ditch completely and just flow out into our field, which meant that even in the summertime, we couldn’t plow it.”

Molli and McGlothlin reached out to King County’s ADAP engineers for assistance on restoring their drainage in 2015. The program provides technical and financial assistance to land owners of agricultural property.

“The goal is to take ditches and small waterways in agricultural areas that have been neglected or not maintained over a certain period of time, and remove the sediment so the water can flow freely,” Molli explained. “Remove whatever invasive things might be growing in there. There is a lot of blackberry and Reed Canarygrass.”

That Reed Canarygrass (Phalaris arundinacea) is a major problem with streams and waterways in King County.

Lou Beck, engineer III with the Water and Land Resources Division of the Department of Natural Resources and Parks, explained that drainage ditches and waterways are often clogged with the plant, worsening the already negative effects of sediment in the streams.

“Reed Canarygrass really chokes the ditches and it really slows the flow of water down and causes sediment to fall out quicker,” he said. “When you have that in your channel it fills up that much quicker and then layers of reed canary grass fall in it over and over and you get matted organic material.”

In order to counter the invasive species, a shade canopy is planted after the work is completed. By out-competing the Reed Canarygrass and allowing other plants to cover the water, erosion of the ditches is decreased and water temperature is kept low.

“It’s really a big water quality benefit,” Beck said. “If you get that shade over the stream it’s keeping the water temperatures low. That’s such a big problem we are having in this region. High water temperatures are unhealthy for the fish.”

No fish were identified at Goose and Gander Farm, so the operation was able to proceed faster. Large metal plates block off a section of the ditch to stop the water flow while an excavator dug out the sediment at the bottom. The clean water from the river was pumped around the isolated section of the stream and returned to the restored ditch.

According to Beck, in the past there were very few limitations on what farmers could do with their land in terms of digging ditches for drainage. Over the past 40 years, regulations and limitations on how farmers could maintain their drainage have become more prevalent. Due to the increased regulations, many farmers stopped maintaining that aspect of their property.

“The end result is that if farmers continued to go through the process of maintaining these ditches the way they always had, they were getting in trouble for that,” he said. “There was about a 30-year span of time when a lot of people just stopped. A lot of these ditches hadn’t been touched for a very long time.”

The lack of maintenance led to negative impacts on the farmland, reducing the usability of land next to the drainage ditches. King County started ADAP as a way to restore the land and help farmers use more of their property.

“At first it was just hitting some really high-profile areas along channels that were big problem areas,” Beck said. “They put a lot of resource into those. Ames Creek was a very large project that was done by the ADAP program.”

In 2011, King County and the Washington Departments of Ecology and Fish and Wildlife revised their best management practices in order to streamline their permitting process, requiring only one permit from land owners, the Hydraulic Project Approval, before work could begin on clearing ditches.

To qualify for ADAP assistance, the drainage area must meet certain conditions including size, amount of water flow and modification history. King County engineers will physically assess the area and, if the criteria are met, will provide technical assistance to get landowners through the permitting process, as well as survey engineering plans, planting plans and archaeological review with the county.

After working with King County in the preliminary stages and watching the restoration crew work on the drainage, Molli was surprised at the speed and efficiency of the ADAP process.

“The process was nicer than I was expecting,” she said. “It was fairly easy from our perspective, just having people show up and do the things they needed to do.”