About Gray’s Bay Dam:

Gray’s Bay Dam is located at the outlet of Lake Minnetonka into Minnehaha Creek. The dam was built in 1979 to help control flooding on Minnehaha Creek and Lake Minnetonka.

The dam is managed by Minnehaha Creek Watershed District according to an operating plan:

• Developed over the course of 10 years with local, state, and federal partners and was approved by local municipalities and the Minnesota Department of Natural Resources
• Created using historical lake levels
• Designed to mimic natural conditions throughout the year and to account for changing weather
• Prescribes discharge zones depending on the time of year, the existing lake level, downstream capacity in Minnehaha Creek, and forecasted precipitation
• Operated spring through fall and closed during the winter season

The management goals of the dam are to:

• Reduce flooding
• Keep water in the creek during dry periods
• Enhance recreation, wildlife, and aquatic life
• Improve or maintain conditions on the lake and creek

For more information on the lake water quality grades, visit Understanding Lake Water Quality Grades. For more detailed data, visit our Annual Monitoring Reports page.

While these grades give a general sense of the health of a lake, they are far from the whole story. District researchers are developing a new, holistic way to understand the overall health of the watershed. The E-Grade program will use a wide array of criteria to evaluate not only lakes, but other natural resources throughout the watershed.

Read the 2016 Annual Research and Monitoring Report.

Christmas Lake Subwatershed

Dutch Lake Subwatershed

Gleason Lake Subwatershed

Lake Minnetonka Subwatershed

Lake Virginia Subwatershed

Langdon Lake Subwatershed

Long Lake Creek Subwatershed

Minnehaha Creek Subwatershed

Painter Creek Subwatershed

Schutz Lake Subwatershed

Six Mile Creek Subwatershed

KEY 1

- = Waterbody was not monitored in 2017
n/a = There was insufficient data
*= Bays not monitored due to water quality similar to adjacent bay (see Key 2) 
Blank = Insufficient number of years of data to calculate average

KEY 2: Lake Minnetonka Bays with Statistically Similar Water Quality

Lower Lake North – Lower Lake South
Carman Bay – Spring Park Bay

ETC:

Lakes not monitored by MCWD are monitored by:
MPRB = Minneapolis Park and Recreation Board
CAMP = Metropolitan Council Environmental Services' Citizen Assisted Monitoring Program
TRPD = Three Rivers Park District

NOTE: Lake grades are no longer being calculated for wetlands or water bodies with wetland characteristics (e.g., Bass Lake, Diamond Lake, and Mud Lake).

The Minnehaha Creek Watershed District's water quality lake grading method was developed in 1989. The lake grade shows how one lake measures up compared to other area lakes and indicates the perceived condition of the open water. Three water quality measurements are combined to create each lake grade. However, there are also other factors that contribute to lake condition, including precipitation. aquatic plants, fisheries, harmful chemicals, and over-use.

Understanding Lake Water Quality Grades

The grades consider what is average or normal for lakes in a given area. What is a "C" in one part of the country might not be a "C" elsewhere. However, within the seven-county metro area, grades can be compared.

The Minnehaha Creek Watershed District compiles water quality monitoring data for lakes and streams in an annual monitoring report. The monitoring report summarizes the data collected in the last year. The technical report provides more detailed data on subwatersheds and explains the District's methodology.

To obtain a past report or other water quality data, contact our Research & Monitoring Program Manager.

• 2016 - Research and Monitoring Report
• 2015 - Technical
• 2014 - Monitoring (2014) | Technical (2014)