LYON COUNTY — It looks like the rain and snow are finally letting up in the Marshall area, but now area communities are struggling to deal with the excess water swamping their sewer systems.

“It’s a combination of several different things,” said Marshall wastewater superintendent Bob VanMoer. “A lot of it is the ground is so saturated,” but improper drainage from sump pumps is another definite factor, he said.

The city of Marshall is among several area communities this week reminding residents not to discharge sump pumps into the sanitary sewer system. Sump hoses should run out into the yard or into the street where the water can drain into the storm sewer system.

VanMoer said Thursday the Marshall wastewater plant was receiving flows much higher than normal, around 9.4 million gallons. The plant is designed to treat an average of 4.5 million gallons per day. Normally at this time of year, VanMoer said, the wastewater plant only gets around 3.5 million gallons of wastewater a day.

The city of Marshall issued a public notice Thursday reminding residents that it’s illegal to discharge sump pumps, foundation drains, or any other ground or surface water into the sanitary sewer system after April 1. Marshall does allow residents to apply for permits to discharge sump pumps into the sanitary sewer, but only between Nov. 1 and March 31.

“Clean water” connections like sump pumps aren’t good for the sanitary sewer system, said VanMoer and Marshall Public Works Director Glenn Olson. If the system is overwhelmed with extra flow, it can cause sewer backups into basements. It can also lead to the city having to discharge untreated sewage into the Redwood River.

Olson said it’s very seldom that Marshall has to bypass the sanitary sewer into the river. However, he said recently there’s been a significant amount of additional water flowing into the wastewater treatment plant. Some of that problem has come from illicit sump connections, he said. There have even been instances where residents opened manholes in order to drain water from their yards, Olson said.

Cities around the area have taken to social media, posting warnings about improper sump pump discharges, and in the case of the city of Porter, declaring a state of emergency because of groundwater flooding and fresh water “overwhelming” the sanitary sewer system.

Porter’s notice said residents are being asked to conserve water and limit discharges into the city sewer system. If residents have ground water entering their homes through floor drains, they are being asked to contact a member of the Porter City Council or the city water/sewer department. Porter will also be taking steps to drain standing water that has pooled on lots around town, the notice said.

Communities around Lyon County, including Balaton and Minneota, have been dealing with increased wastewater flows, and reminding residents to discharge their sumps properly.

“The big thing is, it’s really hard on our lift stations,” Minneota City Administrator Shirley Teigland said of the extra water in city sewers. “It also fills up our lagoons considerably faster.”

The city of Cottonwood had a wastewater flow of around 950,000 gallons on Wednesday, said City Administrator Teather Bliss.

“Every city’s dealing with it,” Bliss said of the excess water in the sanitary sewer. But illegal drainage discharge does pose a risk to Cottonwood’s lift stations and wastewater ponds. Beyond that, it could also get the city in trouble with the Minnesota Pollution Control Agency.

Bliss said the MPCA sent Cottonwood a letter setting phosphorus limits for city wastewater. Having surface and ground water — which can contain phosphorus from sources like lawn fertilizer — get into the wastewater system can push it over the limit.

On the city of Cottonwood’s Facebook page, a post reminded residents that it’s against city ordinances to discharge sump pumps into the sanitary sewer system. Cottonwood allows the discharges by permit during the winter months, but not after April 1, Bliss said.

“I don’t know if the awareness is out there yet,” she said. It was part of the reason for the posted notice.

Saturated soil, heavy snow, and rain this week have all helped set the stage for excess water in area communities. Over the past week, Marshall received a total of 2.9 inches of rain, said Alex Trellinger of the National Weather Service office in Sioux Falls. The heaviest daily total was recorded on April 10 and 11, at 1.64 inches. On Tuesday and Wednesday, Marshall got 0.38 inches of rain, and a little more than a quarter-inch on Wednesday and Thursday.

While there’s still a slight chance of showers on Sunday, the weather in the Marshall area looks like it will be sunnier and warmer over the next few days, Trellinger said. The NWS weekend forecast shows temperatures in the 60s, with a high temperature of 79 degrees on Saturday.

The Redwood River in Marshall is under a flood warning until 8:30 a.m. Saturday, but water levels are projected to fall. The Redwood River gauge in Marshall recorded the river’s stage at about 14.6 feet on Thursday afternoon, down from a crest of 14.77 feet, the National Weather Service reported. Trellinger said the river crested around 11 p.m. Wednesday.