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Comparison of Streamflow in Maine to Seasonal Aquatic Base Flow

May 19, 2026
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This web application provides the latest streamflow values for U.S. Geological Survey (USGS) streamgages in Maine relative to seasonal aquatic base flows associated with the State of Maine In-stream Flows and Lake and Pond Water Levels rule (Maine Department of Environmental Protection, 2026a).
 
The State of Maine In-stream Flows and Pond Water Levels rule, Chapter 587 establishes river and stream flows and lake and pond water levels to protect natural aquatic life and other designated uses in Maine’s waters. The rule applies to direct or indirect withdrawal, removal, diversion or other activity or use that alters the natural flow or water levels of a non-tidal fresh surface water of the state. These waters include rivers, streams, brooks, lakes and ponds that are classified state waters (Maine Department of Environmental Protection, 2026b).
Table information from Maine Department of Environmental Protection, 2026c.  Table is provided for informational purposes relative to USGS streamflows.
 
Threshold Volumes
(Withdrawals that fall below regulatory concern)
Rivers, Streams or Brooks
Lakes and Ponds - GPA
 Area (acres)Threshold (gal/wk)
20,000 gallons per day<1030,000
1% of 7Q1010-30100,000
V = 168.031 × A1.1, where V is in gpd and A is the watershed area in mi231-100300,000
 101-3001,000,000
 301-1,0003,000,000
 1,001-3,00010,000,000
 3,001-10,00030,000,000
Note: 50,000 gpd from groundwater greater than 500 feet from Stream

 

References

 

Maine Department of Environmental Protection, 2026a, Sustainable Water Use Program, Ch. 587 Q&A, Maine Department of Environmental Protection, accessed May 11, 2026, at https://www.maine.gov/dep/water/swup/587qa.html.

 

Maine Department of Environmental Protection, 2026b, Chapter 587: In-stream flows and lake and pond water levels, accessed May 11, 2026, at https://www.maine.gov/sos/sites/maine.gov.sos/files/content/assets/096c587.doc.

 

Maine Department of Environmental Protection, 2026c, Title 38: Waters and navigation, Chapter 3: Protection and improvement of waters, Subchapter 1: Environmental Protection Board, Article 4-B: Water withdrawal reporting program, accessed July 14, 2026, at https://legislature.maine.gov/statutes/38/title38sec470-B.html

 

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