Special Feature: One Ton at a Time

Washington County groups get creative to reduce runoff and improve water quality in the lower St. Croix River.




5 minute read

Lake St. Croix Beach

Lake St. Croix Beach was full of people one August afternoon last year, as folks sought the summer sun and the cool water, like they have for many years. But swimmers couldn’t help noticing green particles floating in the water.

Such algae is not a normal part of the river. Humans are largely to blame for its increase, the result of excess runoff from farm fields and lawns, and discharges from wastewater treatment plants. But today, people can also take pride in the fact we are starting to slow the runoff.

Public agencies declared the lower part of the St. Croix River – the wide, slow-moving stretch from Stillwater to Prescott known as Lake St. Croix – as “impaired” in 2008. The designation was due to those unnatural levels of nutrients in the water, particularly phosphorus.

“As the population here continues to grow, and as other lakes and rivers continue to degrade, if we don’t protect our water resources, we don’t have a National Park,” says Deb Ryun, executive director of the St. Croix River Association, citing the river’s designation as a Wild and Scenic Riverway. “We have the cleanest tributary to the Mississippi River, and the nation is looking at the work we do as an important model.”

The “impaired” designation five years ago set in motion efforts to reduce phosphorus in the river by 20 percent by the year 2020, a goal of 360 tons/year, which has been identified as essentially its pristine level. (That goal is also the inspiration for St. Croix 360’s name.)

From the beginning, it was obvious that there would be no silver bullet for restoring the St. Croix. Big questions remained about the river’s complex chemistry, how to efficiently use limited resources, and where to focus efforts. Recent projects have started to answer some of the questions.

Prioritization innovation

The final analysis showing areas of Washington County with the highest potential for reducing runoff to the St. Croix River
The final analysis showing areas of Washington County with the highest potential for reducing runoff to the St. Croix River

“There is a lot of talk about focusing efforts on the most important projects, but how do you determine what they are?” asks Ryun. “Just guess?”

There was no guesswork involved in Washington County, which runs the length of Lake St. Croix on the Minnesota side. The Washington Conservation District used high-tech mapping to identify more than 50 areas with the greatest opportunity to reduce phosphorus flowing into the St. Croix, and then worked with five private landowners to start managing the runoff from their property.

The Top50P! project’s innovation was primarily in how the priority projects were identified. The agency used geographic information systems (GIS) software to analyze the county’s rural agricultural areas and rank them on a number of key factors.

By looking at vegetation, soil type, and steepness and length of slopes, technicians came up with a map showing St. Croix River tributaries that would benefit the most from runoff management. The priority areas were those with high erosion potential and which drained directly to the St. Croix River.

After the complicated computer work, staff got on the ground. They traveled to priority areas, looking for eroding ravines and gullies that would provide a route from fields to the river. People who owned land with high potential for improvement were then contacted and asked if they were interested in being part of a project.

Jay Riggs, district manager of the Washington Conservation District, says this is unfortunately not how partnerships with private property-owners have usually worked in the past.

“Historically, a landowner would come in and ask for help fixing a ravine,” Riggs says. “This time, we identified areas with the biggest bang for the buck and then asked landowners if they wanted to work with us.”

Finding the right landowners was a challenge, because there was no time to waste. The projects needed to move forward rapidly to meet funding requirements.


Despite the constraints, five sites were identified where the landowner was interested in helping solve a runoff problem and the work could be done quickly. Then it was a matter of installing a fairly uncomplicated tool called a Water and Sediment Control Basin.

To construct one of these basins, a berm is built at the top of a gully where a field is washing its soil and nutrients down toward the river. During rainfalls, runoff builds up behind the berm. The water stays in this short-lived pond just long enough for sediment, phosphorus and other material to settle out of the water.

One of the projects was on Walter Mills’ property where it drains to Trout Brook, which in turn passes through Afton State Park and joins the St. Croix. In fact, there is a very large sand beach on the river at the outlet of Trout Brook. As Riggs says, that’s a good indication of erosion up the creek.

The project on Mills’ property captured runoff from 14 acres, reduced phosphorus flow to the St. Croix by 25 pounds per year, and cost $28,000, split between the landowner and the South Washington Watershed District. (No word on whether or not the Afton State Park beach will shrink.)

Water and Sediment Control Basin on Stanley Hubbard's property.
Water and Sediment Control Basin on Stanley Hubbard’s property. (Photo courtesy Washington Conservation District)

Another runoff control project was on the Lakeland property of Stanley Hubbard, founder of the KSTP media companies. A basin on Hubbard’s land will reduce runoff from 16 acres by about 16 pounds per year, at a cost of about $35,000, which was split between the St. Croix River Association, the Middle St. Croix Watershed Management Organization, and Hubbard.

All told, the first five Top50P! projects exceeded expectations. While originally predicting a reduction of 50-100 pounds of phosphorus, the runoff control practices are actually cutting pollutant flows into the St. Croix by 163 pounds.

“If we implement five of these projects each year, we will achieve a quarter of the county’s share of phosphorus reduction,” says Riggs.

Most of the recent funding went to identifying priority areas. Now that the work is done, there is a list of 50 more deserving projects, and each would put a significant dent in the county’s runoff. Riggs and his staff are seeking funding to keep building basins.

River of promise

What is happening in Washington County is about the future of the St. Croix as much as its abused past and polluted present. With the technology available to pinpoint priority areas, and the tools available to reduce runoff, the potential for the river is promising.

The Top50P! program was one of four projects made possible by a $500,000 grant to the St. Croix River Association from the Minnesota Pollution Control Agency, with funding supplied by the 2008 Legacy Amendment’s Clean Water Fund. (Look for future articles about other work made possible by the grant.)

The River Association’s Deb Ryun led a team of experts who reviewed applications for the funding, and says all the projects submitted were worthwhile.

“We ran out of money before we ran out of good things to do,” Ryun says. “The lesson learned is that it’s a big watershed and it’s going to take a whole lot of resources to go forward. This is not a one year, one shot effort.”

With another summer here, the St. Croix River’s beaches are getting busy again. There is a lot of work left to do, but swimmers can enjoy the fact that the water should only be getting clearer in the future.


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Special Feature: One Ton at a Time