3.3 Water Quantity
The District has operated a Hydrologic Data Program since 1968; the program was significantly expanded in 1997. Water quantity is monitored at numerous locations throughout the watershed, including flow gauging at eight locations along Minnehaha Creek and 15 sites along major tributaries to Lake Minnetonka.
Continuous water level monitoring is conducted on Minnehaha Creek at Grays Bay Dam (Lake Minnetonka Outlet) in Minnetonka, at the I-494 crossing, and Browndale Dam in Edina. Continuous water level monitoring was conducted on Painter Creek and Long Lake Creek in the Upper Watershed. In addition, thirty-three lake level recording stations are routinely monitored by MCWD staff or volunteers.
The District maintains an XPSWMM hydrologic and hydraulic model of the watershed to aid in analysis and decision making. The 2003 Hydraulic, Hydrologic, and Pollutant Loading Study (HHPLS) included detailed XPSWMM and P-load modeling of the current and 2020 hydraulic and hydrologic conditions in the subwatershed. That modeling includes the following results for modeled locations (lakes, ponds, channels, and crossings) within the subwatershed:
- Existing Normal Water Level;
- Existing High Water Level for the 1.5 year, 24-hour and 100-year, 24-hour events;
- 2020 predicted HWL for the 100-year, 24-hour event; and the
- Existing High Water Level for the 100-year, 10-day snowmelt event.