The Crow Wing County Land Services Department has begun revising the 2008 Local Comprehensive Water Management Plan (water plan).
Water planning is identifying what works best to protect and enhance Crow Wing County’s water resources. Part of this identification process is to measure the county’s water resources to observe trends to prioritize resources for protection or restoration efforts.
As part of the revision process, the Crow Wing County Land Services Department is working to include a number of recent scientific studies and data-driven measures that will provide a baseline to help guide land use planning and project implementation.
In January, the county completed Phase II of a lakeshore research study project to calculate the amount of impervious surface coverage on larger lakes in Crow Wing County. This study was conducted in response to the 2011 Land Use Ordinance revisions that require performance standards depending on the amount of impervious coverage per lot.
Impervious surfaces are hard surfaces on a lot such as rooftops, sidewalks, patios and driveways that don’t allow water to soak into the ground.
Impervious surface data was calculated using high-resolution aerial photography and property sketches from the Property Valuation and Classification Office. The amount of impervious surface was calculated for the entire riparian lot as well as within 250 feet and 500 feet of the shoreline to determine how much impervious surface was located close to the shoreline.
Phase I was conducted earlier in 2012 and included 12 lakes. Phase II included another 20 lakes.
The results of both phases of the project indicate that the average impervious surface percentage on riparian lots on the county’s larger lakes is less than 10 percent.
For example, Lake Edward, Lake Hubert and Lower South Long Lake were all measured at 6 percent, Upper South Long was measured at 7 percent and Whitefish was measured at 5 percent. The full report can be viewed online at http://www.co.crow-wing.mn.us/index.aspx?nid=925.
The lakes measured correspond with the lakes that were part of a water quality screening project that was conducted in 2009 and 2012 to determine whether a water quality trend could be determined based on all the available water quality data that had been collected over the years. These reports are available online at: http://www.co.crow-wing.mn.us/index.aspx?NID=705.
With more than 500 lakes in the county, these tools are very effective to prioritize which lakes to focus protection or restoration strategies on.
“Studies have shown that water quality begins to decline when impervious surface coverage reaches 12-15 percent,” said Land Services Supervisor Chris Pence. “This local data about Crow Wing County lakes will help guide land use decisions about keeping our lakes clean.”
The county’s revisions to the Land Use Ordinance in 2011 include performance standards for stormwater management and shoreline buffers that take effect at 15 percent and 20 percent impervious coverage, respectively.
In addition to surface water, Crow Wing County is also gathering data on ground water quality, including levels of nitrate.
“Since we’ve begun testing for nitrates the last few years, we have observed nitrate levels that are generally well below the safe drinking water standard of 10 parts per million. This is great news,” said Mitch Brinks, water protection specialist.
All of this data will be included in the 2013 revision to the water plan, which has identified surface water, ground water and aquatic invasive species as its top priority concerns.
Water planning questions can be directed to Mitch Brinks at 218-824-1125.