Research On Costs For New Water Supplies Highlights Importance Of Conservation

There’s a problem brewing beneath our feet in Washington County. The county is home to the Mississippi and St. Croix Rivers, approximately 250 lakes, dozens of streams, and countless wetlands. Yet, despite this apparent abundance of water, local municipalities are looking toward the future and wondering, “Will there be enough water for people to drink?” The short answer to this question is yes, but it won’t come cheap.

By 2030, the Metropolitan Council predicts that there will be major drawdown of the Prairie du Chien / Jordan Aquifer in portions of Dakota and Washington Counties.

Last year, the Metropolitan Council completed a two-year water supply planning study in cooperation with nine cities in Washington County – Bayport, Cottage Grove, Lake Elmo, Newport, Oakdale, Oak Park Heights, Stillwater, St. Paul Park, and Woodbury (Washington County Municipal Water Coalition). The goal was to identify and provide cost estimates for potential new municipal water sources to meet future needs. Currently, 100% of the water used for drinking, household use, irrigation, and industrial processes in Washington County comes from groundwater aquifers. The nine cities participating in the study primarily use water from the Prairie du Chien-Jordan aquifer, which is pumped via high-capacity wells. Groundwater is naturally clean, requiring little to no treatment before use, and is generally cheaper to access and distribute than surface water from rivers and lakes.

Click on the image above to access an interactive map of priority areas for future well testing in Washington County.

Already, however, there are signs that groundwater use in Washington County may not be sustainable. In some parts of the county, aquifers are contaminated by per- and polyfluoroalkyl substances (PFAS) and nitrates. In other locations, groundwater pumping can impact stream and lake levels. In addition, the total population of the nine cities is expected to grow by 27% by 2040.

In the water supply study, the municipal water coalition looked at four possibilities for meeting increased water demand in the future: 1) Reusing water pumped for pollution containment on 3M property in Woodbury and Cottage Grove; 2) Building a water treatment plant on the Mississippi or St. Croix Rivers; 3) Purchasing and piping in water from St. Paul Regional Water Supply; or 4) Drilling new wells to access more groundwater.

Each of these potential solutions comes with a unique set of challenges. 3M currently pumps approximately 3,000 gallons per minute of groundwater from pollution containment wells on the border of Woodbury and Cottage Grove. The water is treated with granular activated carbon to remove perfluorinated compounds (PFCs) before being used as process water, and eventually discharged to the Mississippi River. Because the water is contaminated, however, it would require expensive treatment to make it safe for drinking. Cost estimates range from $24.7 million to pump non-potable water from 3M Woodbury to the Northern Tier Refinery in St. Paul Park ($1.20/1000 gal) to $37.5 million to treat the water with reverse osmosis and use it for drinking water in Cottage Grove and Woodbury ($4.70/1000 gal).

Building a water treatment plant on the St. Croix or Mississippi River would cost $68-184.9 million, depending on where the plant is located and how many communities it serves. Water fees would range from $3.70-6.20/1000 gal. It would be relatively affordable to connect some communities to the St. Paul water supply ($4.8 million to serve portions of Woodbury or $13.1 million to serve all of Oakdale) but other communities in the East Metro may be looking to St. Paul for water as well. Delivering water from St. Paul to all of Cottage Grove and Woodbury would cost $96 million ($4.23/1000 gal). The final option – drilling new wells in Cottage Grove, Woodbury or Denmark Twp. – would provide the cheapest water rate ($1.10-1.20/1000 gal) but would not address underlying concerns about drawing down the aquifer. A new well field would cost $25-30.6 million.

Nine cities in Washington County are exploring options for meeting future water needs, including drilling new wells, buying water from St. Paul, or building water treatment plants on the Mississippi or St. Croix Rivers.

The municipal water supply study conducted in Washington County presumes that per capita water use will remain the same as the population grows. In reality, nearly 30% of the water used in the nine communities each year is for “non-essential” uses, namely irrigation. In fact, as much as half of the current water supply infrastructure in place was built primarily to meet peak water demands during the summer. Reducing the non-essential water use by 1.5 billion gallons per year would save communities approximately $3 million annually. New approaches to landscaping, more efficient irrigation, low flow toilets, faucet aerators, and water-efficient appliances are part of the solution, along with larger projects such as reusing stormwater for irrigation, and upgrading commercial and industrial facilities in the county.

Municipal water use during the summer spikes dramatically due to lawn watering.

Learn more about why and how to conserve water at the Met Council website.

You can also take a bite out of your summer water use by installing rain barrels to capture and reuse rainwater at your home. Order now at RecycleMinnesota.org and pick yours up on: April 22 in Blaine; April 28 in Hugo; April 29 in Anoka, Maplewood or North Branch; April 21 in St. Cloud; May 5-6 in Chanhassen; May 6 and 8 in St. Louis Park; or June 10 in St. Paul.

Rain barrels are one way to reduce summer water use.