October is Watershed Awareness Month, by proclamation of Story County Conservation Board and city councils in Ames, Nevada, and Gilbert. Okay, so what exactly do we want people to be aware of? I would suggest the following progression…

Stage 1 of watershed awareness

Stage 1: What’s a watershed?  Who cares?

A watershed is the land area that drains to a common outlet. Imagine a river valley between two mountain ridges. Now replace that mental image with gentle hills–we’re in Iowa. But more important than knowing the definition is understanding why it’s important: because water flows downhill, actions on land can have consequences for downstream water bodies.

Perhaps the best illustration of this principle is an incident from 2020. Following a power outage, some Hy-Vee employees in Ankeny poured 800 gallons of spoiled milk down a storm sewer, turning the nearby creek white, killing 2,000 fish, and costing their employer almost $25,000 in fines and restitution. The silver lining of this boneheaded decision was that it made the news and reminded many Iowans that yes, storm sewers drain to rivers (usually without any treatment) and so we should think twice about what we pour or let wash in. The same principle applies to ditches, gullies, and drainage tiles.

Want a more positive framing? Watch this one-minute video we created with the City of Ames about the South Skunk River, and how cities and farms in the watershed can make a difference.

Stage 2 of watershed awareness.

 Stage 2: What’s my watershed(s)?

It’s one thing to know that my actions could (in principle) help or harm some downstream water body. It’s another thing to know that what goes down my neighborhood storm drain ends up in Ioway Creek at Brookside Park, a place where I’ve taken my kids to play. In 2018, we partnered with Story County Conservation to put up watershed and creek signs, in hopes that more people make those kinds of connections.

Creeks flow to rivers and rivers flow to the sea (except in endorheic basins) so we live in multiple, nested watersheds.  A convenient way to represent this is with the US Geologic Survey’s Watershed Boundary Dataset, which has mapped American watersheds at six levels and assigned them each a unique hydrologic unit code (HUC).  You can look up your “watershed address” with our interactive map.  For example, that grocery store in Ankeny is in the lower Fourmile Creek watershed, within the watershed of Red Rock Lake, within the watershed of the Des Moines River, and within the upper part of the giant Mississippi River basin.

Watershed awareness, stage 3

Stage 3: Who are the other people in my watershed?

One reason to learn which watershed you live in is to connect with other people who are concerned with flooding, water quality, fisheries, and recreation.

Twenty-eight watersheds in Iowa have a Watershed Management Authority with representatives from local governments in the watershed (cities, counties, and soil and water conservation districts) who might collaborate on water quality or flood control projects.  Fourmile Creek WMA is one of the more active WMAs; its member jurisdictions pooled money to hire a watershed coordinator who can work with farmers and landowners.  In some watersheds, farmers and landowners have access to additional cost-share programs or receive higher priority when they apply.

In some watersheds, a volunteer group, land trust, or other non-profit organization organizes projects to protect the water or raise public awareness.  For example, the lake at Ada Hayden Heritage Park in Ames has a friends group, while the Raccoon River has a volunteer Watershed Association in addition to three WMAs.


Unfortunately, I’m not aware of any central clearing house where one can find out what groups and projects are active in your watershed. I’m also not aware of any plans by state leaders to provide WMAs with stable funding or to delegate to them any powers that would help them accomplish their tasks. Watershed projects tend to be grant-funded (and thus short-lived) and watershed coordinator jobs often have high turnover.

Stage 4 of watershed awareness

Stage 4: What are the issues in my watershed?

Some watersheds have management plans (like this one for Fourmile Creek) that identify creek- or lake-specific problems and solutions. However, in many cases, the data needed to evaluate a problem and track progress toward solutions is missing until volunteers, universities or local government step up to do monitoring.

Knowing which issues go with which watershed can help us prioritize and find solutions.

  • Not every stream has the right conditions to support a trout fishery (like Bloody Run in Clayton County).
  • Not every stream has a history of destructive floods (like Fourmile Creek in Polk County).
  • Not every lake or reservoir has suffered from toxic algae blooms (like Brushy Creek Lake in Webster County).
  • Not every river is deep enough and has access for canoeing (like the South Skunk River in Story County).
  • Not every river affects the supply and safety of drinking water for thousands of people (like the Raccoon and Cedar rivers).
Stage 5 of watershed awareness

Stage 5: How big are the problems and solutions in my watershed?

The most difficult thing to understand about a watershed is the scale.  It helps to have some familiar reference points.  Here are some of mine.  (I’ve used an app that makes it easy to delineate a watershed for any point of interest.  The area is rounded to the nearest 100 acres.)

  • 1,000 acres: Creek at Tedeco Environmental Learning Corridor, Ames.
  • 5,900 acres: Peas Creek at the Ledges State Park.

At the HUC12 scale, most creeks are too wide to jump across, but shallow enough to wade.  Watersheds are small enough to fit in one county.

  • 14,100 acres: Walnut Creek at Neil Smith National Wildlife Refuge
  • 24,000 acres: Bloody Run at Marquette.
  • 56,800 acres: Fourmile Creek at Sargent Park in Des Moines.

At the HUC10 scale, it might be called a creek, but it often has enough water to float a canoe, and watersheds usually cross a few county and city lines.

  • 132,700 acres: Ioway Creek at Brookside Park in Ames.
  • 173,500 acres: Maquoketa River at Manchester.
  • 209,300 acres: South Skunk River at River Valley Park in Ames.
  • 356,100 acres: Rathbun Lake

At the HUC8 scale and beyond, the rivers are big and the watershed meetings can involve many jurisdictions and long drives.

  • 586,400 acres: Floyd River at Sioux City
  • 1,285,200 acres: North Raccoon River at Squirrel Hollow Park in Jefferson
  • 2,306,200 acres: Racoon River at Waterworks Park, Des Moines
  • 3,733,300 acres: Des Moines River at Saylorville Reservoir
  • 97,191,700 acres: Mississippi River at Dubuque

For each of these watersheds, you’d need to plant about a third of the cropland to cover crops to reduce nitrogen and phosphorus in the stream by 10%.  Most watershed plans will include more ambitious long-term goals and more complicated scenarios to achieve them, but this is a handy benchmark for thinking about the scale of change needed.  Reaching the 1/3 mark for cover crops in a watershed would be good progress toward our 45% nutrient reduction goals and could produce a big enough improvement in water quality in the stream that we could conceivably measure it, though maybe not with test strips (i.e. from 10 to 9 mg/L of nitrate, from 0.40 to 0.36 mg/L of total phosphorus).

I don’t mean to discourage anyone, but I’m not aware of any watershed project in Iowa that has achieved success on this scale.

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