WATER QUALITY SUMMARY

ECHO Lake, Presque Isle

MIDAS: 1776, Sample Station # 1

The Maine Department of Environmental Protection (Maine DEP) and the Volunteer Lake Monitoring Program (Maine VLMP) have collaborated in the collection of lake data to evaluate water quality, track algal blooms, and determine historical water quality trends. This dataset does not include bacteria, mercury, or nutrients other than total phosphorus.

Water quality monitoring datasets for Echo Lake have been collected since 1976. During this period, 9 years of basic chemical information were collected, along with 18 years of Secchi Disk Transparency (SDT) measures (continuous from 1976-84 and 1998-05, only 1990 sampled in interim period) . In summary, the water quality of Echo Lake is poor, based primarily on measures of SDT, total phosphorus (TP), and chlorophyll-a (Chla). The potential for nuisance summertime algal blooms on Echo Lake is high.

Water Quality Measures: Echo Lake is a non-colored lake (average color 24 SPU) with an average SDT of 2.2 meters (7.2 feet). The range of upper water column TP for Echo Lake is 13 to 41 parts per billion (ppb) with an average of 20 ppb, while Chla ranges from 2.9 to 42.1 ppb with an average of 7.7 ppb. Recent dissolved oxygen (DO) profiles show little DO depletion in deep areas of the lake since the lake is too shallow to thermally stratify in the summer. The potential for phosphorus to leave the bottom sediments and become available to algae in the water column (internal recycling) is low based on recent oxygen measurements, but there may be rich bottom sediments which contribute to the high phosphorus, especially during warmer summer months.

Comments: The flushing rate is the amount of time required for the lake water to be renewed each year and is a function of the watershed size and volume. The average flushing rate and volume for Echo Lake have not been adequately determined. Due to the high algae growth, the lake is listed by Maine DEP as “water quality limited”. More work will be done in the coming years to determine the reasons for this and potential for restoration of the lake.

Nutrient Management: Echo Lake is on the Maine DEP/EPA 2004 303(d) list of waters non-attaining Maine state water quality standards. A Phosphorus Control Action Plan (PCAP) and TMDL study/report will be drafted (2005-06) and after Public Review and US-EPA-approval (2006-07), will be found on the following Maine DEP webpage: http://www.maine.gov/dep/blwq/docmonitoring/tmdl2.htm .

See the Maine DEP Explanation of Lake Water Quality Monitoring Report for measured variable explanations. Additional lake information can be obtained by contacting Maine DEP at 207-287-3901 or VLMP at 207-783-7733, and at these Websites: http://www.lakesofmaine.org and http://www.maine.gov/dep/water/lakes/index.html and http://www.mainevolunteerlakemonitors.org .

Filename: echo1776, Revised: 03/2006, By: dbh