Big Hollow Water Quality Project

Big Hollow Water Quality Project Graphic

The Issue

Big Hollow Lake suffers from excess nutrient loading, specifically phosphorous, resulting in large algae blooms and increased pH. The water is still safe - we test it all summer long to be sure of that - the algae and floating plants just make things like boating, fishing, and swimming a bit less appealing at times. Therefore, the lake has been designated as an "impaired" water body in the state of Iowa.

Map of the Big Hollow WatershedWhat's Being Done

Des Moines County Conservation teamed up with the Des Moines County Soil and Water Conservation District (SWCD), the Natural Resources Conservation Service (NRCS), Iowa Department of Natural Resources (DNR), and the Iowa Department of Agriculture and Land Stewardship (IDALS), and secured federal grant funding to hire a consultant (FYRA Engineering) to complete an EPA-approved Nine-Element Plan. This plan, coupled with the DNR-prepared Water Quality Improvement Plan (or TMDL), will identify the actions and practices to implement throughout Big Hollow Lake's 4,400-acre watershed to improve the lake's water quality without having to take drastic measures like draining the lake like what was done at nearby Lake Geode State Park starting in 2018. 

Furthermore, once the Nine-Element Plan is approved by the EPA, the lake will then be eligible for federal funding through the Clean Water Act as well as other local, state, and federal programs. 

How You Can Help

If you live in, or own land inside Big Hollow's watershed, you are the first line of defense for the lake's water quality. Implementing conservation practices on your property to reduce sediment and nutrient runoff (such as terraces, buffers, cover crops, retention ponds, etc.) is key to addressing these issues. As we progress past the planning stages and into implementation, there will likely be funding available to help install these practices on your land. Talk to conservation professionals at Des Moines County Conservation or the local NRCS office to see what you might be able to do. 

If you don't have land inside the watershed but care about the park and all the recreation opportunities it offers, you can be an advocate for the lake in many ways. Through this planning process, there will be opportunities for public input, surveys conducted, and events to attend. Participate in these so the policymakers and granting entities can see how much support there is for this effort. You can also volunteer at the park to help with management efforts around the lake. 

Take our Survey

We need your input on water quality and recreation at Big Hollow. Please take this short, 11-question survey.

Watch the presentations from our Water Quality Symposium

On a very rainy June 30, 2021 we held a Water Quality Symposium where professionals from DNR, NRCS/SWCD, and the lead engineer from FYRA, the consultant that is writing the Big Hollow 9-Element Plan, discussed their research, what programs exist to help, and where the project is headed. The videos that follow are those presentations. These can also be viewed on Des Moines County Conservation's YouTube Channel.


Fisheries slides to accompany presentation (PDF)

Engineer's slides to accompany presentation (PDF)