The following is from Delaware State News, delawarestatenews.net/news/report-downstate-drainage-systems-overwhelmed-by-record-rainfall-in-2018
SMYRNA — Delaware saw the most year-to-date precipitation in 2018 since record-keeping began more than a century ago, according to a report issued by the state climatologist’s office.
Though 2018 is past, it appears much of the rainfall has stuck around.
Few are the back roads one can drive downstate where overflowing retention ponds, flooded ditches or standing water in farm fields aren’t a common sight.
According to Brooks Cahall, drainage program manager for the Delaware Department of Natural Resources and Environmental Control (DNREC), this is because groundwater tables are at near capacity and the ability to disperse the overflowed water naturally is diminished in the winter.
“The areas north of Dover and south of the canal were hit especially hard last year — some areas getting up to 70 inches of rain when our usually yearly average hovers around 45 inches,” he said.
“Our office doesn’t measure groundwater. But just in the amount of complaints we’ve been getting — especially in Kent County — we can see that the groundwater level is starting to creep into a problem area.
“Water has three ways of leaving naturally: evaporation, infiltration or it can run off. In the winter we don’t get the evaporation because it’s just too cold and when groundwater is high like it is now, we lose a lot of that infiltration capacity too.”
Mr. Cahall says sometimes drainage issues under these conditions don’t start to dissipate until early spring.
“Usually we start to see a lot of the standing water start to disappear once plants start to grow again and roots take up water,” he said. “Around this time, temperatures start rising again and the days get longer, helping evaporation as well.”
Residents warily eying large puddles as they creep toward their property may begin to wonder: ‘Who’s going to help me if this overflows onto my property?’
The short answer is: “It depends.”
For concerned residents, DNREC’s drainage program is an ideal place to start though, Mr. Cahall says.
“When it comes to specific issues, we either investigate and address them ourselves or route the residents to the correct agency — whether thats the conservation districts, Department of Transportation or local tax ditch organization,” he said.
“We’re not an emergency flood response group though, if someone gets trapped by a flood, they should call 911. We usually investigate longer-term more wide-ranging flooding solutions. Sometimes they are little changes or big projects or just some technical assistance.”
Managed by ‘tax ditches’
Mr. Cahall said Delaware’s flat, near-sea level elevation and geological characteristics put it at an inherent disadvantage when it comes to quickly routing excess water to natural tributaries. Much of the state’s drainage is managed by a fairly complex series of over 200 “tax ditches” that were first implemented almost 70 years ago.
The tax ditches are operated by a patchwork of managers that are local to corresponding water sheds.
“The organizations themselves are their own governmental subdivision and have their own managers but we provide technical assistance,” said Mr. Cahall.
“We usually assess the ditches for things like beavers, bank cave-ins or erosion. Mostly though, they’re managed by the officers who live within the water shed — local people making local decisions.”
Though they’ve operated as intended for many years, Mr. Cahall said the tax ditches were never a “fast” way of dumping excess water.
“The ditch system infrastructure was designed to removed excess water in a 24- to 48-hour period,” he said. “As the landscape in the state has changed over time from heavily agricultural to more suburban areas, people have begun to expect the water to be gone as soon as it stops raining. Because Delaware is so flat, it often takes a couple of days for things to drain out the way they should though, especially when there is heavy rainfall.”
Though resident’s expectations have risen, in some cases their sense of responsibility hasn’t followed suit. While Mr. Cahall says many of the tax ditches are well managed, a few have begun to suffer from a deficit in leadership. Over time, this can lead to unaddressed maintenance issues.
Some ditches struggling
“Most do what they need to, but some of the ditches are struggling,” he said. “The tax ditch laws were originally passed in 1951, so through multiple generations the sense of urgency seems to have faded a bit. I think sometimes we take for granted how things are right now and don’t remember how the landscape looked before this infrastructure was first put into place and how important it is to maintain. Certainly years like 2018 help highlight the need for this type of infrastructure.”
Though no tax ditches in his experience has deteriorated so much as to cause flooding issues, Mr. Cahall recommends that property owners in the state familiarize themselves with their local water shed and any tax ditches that may be relevant to their parcel.
This can be done by visiting dnrec.delaware.gov/swc/Pages/DrainageTaxDitchWaterMgt.aspx and clicking “Delaware tax ditch map” or calling (302) 855-1955 for more information.
With the wave of subdivisions and housing communities that have sprung up around the state over the last few decades came more direct managed drainage management tools like Homeowner’s Association’s retention ponds. Often, an HOA pools funds together from its members to pay for the upkeep of the infrastructure that prevents local flooding. However, in recent years, many of these have ceded that responsibility to the county administration for efficiency and cost-savings.
Kent County has taken on the maintenance of 27 Stormwater Management Districts with another 18 petitions that are currently pending, said county administrator Michael Petit de Mange.
Generally though, malfunctioning drainage infrastructure usually falls under the purview of the Kent Conservation District.
Responding to complaints
“If a stormwater management feature such as a retention pond or a drainage ditch is not functioning property, the body that has jurisdiction is the Kent Conservation District,” said Mr. Petit de Mange. “They oversee and administer the state’s stormwater management regulations for Kent County.
“They’re tied into our permitting process and our land development application process on the pre-development side and then they also do inspections and respond to complaints on the post-construction side.”
At the county-level, Mr. Petit de Mange notes that an equally important function is to restrain development of land that faces a high risk of ultimately being flood damaged.
“We administer the national flood insurance program for the county and we have a floodplain development ordinance that we enforce through the permitting process,” he said. “This is for new construction and it lays out different options and prohibitions for development in the floodplain areas — parcels of land that are prone to flooding.”
As for property downstate currently underwater, fingers are likely being crossed for scant winter precipitation and an early, warm spring.