Power Washing in Cottrellville Township, Michigan

A River Shore on One Side, Farm Ground on the Other

Cottrellville Township is a civil township of 3,406 people at the 2020 census. Marine City sits at its northeast corner, and China Township, Ira Township and Clay Township border it on the north, west and south. The St. Clair River forms its entire east edge and the border with Ontario, with Fawn Island, Ontario, less than a mile off the shore. That layout splits the cleaning in two: damp growth on the river homes along M-⁠29 (River Rd), and clay mud on the farm homes inland.

Martindale Beach, Avalon Beach, Cherry Beach, Broadbridge Station and Roberts Landing sit in a line along M-⁠29, facing a channel that carries international freighters. On these lots the house and deck stand a short walk from open water, and shaded siding and deck boards stay wet for hours after dew. Algae and mildew grow while a surface is wet, so the walls and boards that see the least sun turn green first. A soft wash treats the siding at low pressure, and a shaded deck needs three or more dry days before stain.

The practical washing season here runs April through October. About one home in ten is held for seasonal or occasional use, and a late-spring wash has a cottage clean before the summer stay. Inland, wait for the clay yards to dry after spring rain: the township plan says its soils all carry limits from high water tables and poor drainage, and a house washed over soaked ground picks up a new mud line at the next storm. An early-fall wash before freeze-up sends shaded river walls into winter clean. Our timing guide has the months.

Inland, the township is mostly farmland laid out in square-mile sections, with Starville along Starville Rd and homes spread along Shea Rd, Broadbridge Rd and Marsh Rd. Beaubien Creek and the Marine City Drain run north to south through the flat clay. Several respondents to the township's 2025 survey raised ditch drainage, property flooding and dirt roads. On a house, that shows up as a band of dried mud and road dust across the bottom two or three feet of siding, which a surfactant pre-treatment loosens before a low-pressure rinse. Rinse water inland runs first to a roadside ditch, and on a shore lot to the river, so it is kept out of both.

1970s Houses, Older River Homes and Manufactured Homes

The median home in Cottrellville was built in 1975, and the 1970s were the busiest building decade, with nearly one house in four. On a house that age the siding, trim and roof may date from different years, so the crew walks each wall before the wash starts and mixes for each surface it finds. Black roof streaks, usually traced to Gloeocapsa magma algae, start on north-facing slopes, where shingles dry last after dew. Roof treatment starts at $450, clears them without pressure and repeats every three to five years; our roof streak guide shows the pattern.

About 226 Cottrellville homes date to 1939 or earlier, and the 1975 median puts more than half the township on the far side of 1978, EPA's lead-rule cutoff. Any painted siding or trim on those houses needs a cleaner gentle enough that intact coats stay put and no water is forced behind the laps. Lifting paint should be shown to the owner and left in place. Scraping or stripping over 20 square feet outside a house that old lands inside EPA's Renovation, Repair and Painting (RRP) rule, and only an EPA-certified firm may be paid to do it; ask to see that certificate before hiring paint prep.

Roughly one home in seven is a mobile or manufactured home, including the Shangri La Mobile Home Community on River Rd. Panels and skirting on these homes are thinner than the walls of a framed house. Skirting sits lowest and closest to the yard, so on wet clay it carries the heaviest mud splash and gets a longer pre-soak than the panels above it.