Of Pop-Tops, Scrape-Offs And Flooding

What You Can Do To Help Save Our Watersheds

Our watersheds in Greater Park Hill are experiencing significant changes, literally as I write this column. Pop-tops and scrape-offs. New businesses and expansions of existing businesses. All have a tremendous impact on our watersheds.

The two primary watersheds in this part of Denver – the Montclair Arroyo watershed and the Park Hill Arroyo watershed – need your help. (I find “arroyo” to be the best descriptor for these drainages.)

So, what can you do?

1. Support the preparation of watershed restoration plans.
Help the City of Denver develop a Watershed Restoration Master Plans for the Montclair Arroyo watershed and one for the Park Hill Arroyo watershed. When the next series of public meetings are announced for Montclair Basin, in a month or so, attend at least one of them and share your ideas and opinions. Ask city officials when they expect to initiate a similar process will be launched for the Park Hill Basin. Tell them how you feel about parks and open space, to allow space for flood flows and for all of the other functions parks and open space provide. Tell them how you feel about regulating new development and the placement of fill on floodprone lands. What other ideas do you have?

2. Get to know the street segments in the Montclair Basin where vehicles sit in potential paths for severe flood damage. Encourage city officials to post warning signs on street blocks in the portion of the Montclair Basin in and near Greater Park Hill that face dangerous flood risk. No master planning should be necessary; signs warning of the dangers could be installed now.
Using the city’s own data and floodplain mapping, the map above shows those street blocks where flood depths during a 1 percent annual risk (100-year) flood event would equal or exceed 3 feet, somewhere on that block. There are a small number of blocks where flood depths could equal or exceed 6 feet.
The signs could use wording such as: “This area is subject to periodic flash flooding to a depth of 3 feet (or 6 feet). Flash flooding generally occurs between May and September.”

3. Learn what you can do at your home or business. Attend the upcoming Stormwater Improvements Workshop. The workshop is scheduled for Saturday, Aug. 12, from 9 a.m. to noon at the Greater Park Hill Community office at 2823 Fairfax St. It is specifically designed for residents and owners of small businesses. You will learn some of the steps individual homeowners and business owners can take to help improve the quality of their watershed. You’ll also learn that many landscaping and gardening practices helpful to your watershed are easy to initiate. The workshop is being offered free of charge by the Colorado Stormwater Center.

The second map, below, shows the part of the Montclair Arroyo watershed around the Mayfair Town Center at 14th and Krameria. It also shows the 1 percent annual risk (100-year) floodplain and the location of the “preferred channel.”

Note that the “preferred channel” (the current lowest elevation path that floodwater would follow) is mostly within existing streets. That’s because us humans have made substantial alterations to the natural topography of the area over the past 125 years.

There are numerous businesses and homes located outside the arroyo channel and outside the 1 percent annual risk floodplain, but still within the watershed. The runoff from these “upland” properties contributes to the flood risk in the floodprone bottomlands.

Bottom line, we are all citizens of the watersheds.

Brian Hyde is an expert in floodplain management and stream restoration. He wants your feedback at westerly_connect_brian@comcast.net or 720-939-6039. Past columns can be read at greaterparkhill.org.