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What is the general water quality of Herrington Lake?

By Malissa McAlister, UK Kentucky Water Resources Research Institute

The Herrington Lake reservoir supports many beneficial uses for area residents. These include drinking water, fisheries, and swimming and boating, as well as providing scenic beauty.  

Kentucky’s Division of Water conducts regular water quality sampling to ensure that the water meets specific minimum standards for these uses. They have found that the lake satisfactorily meets the standards required for a drinking water supply source, as well as for its boating and swimming uses.

The Division of Water samples for E. coli as an indicator of pathogens that may be in the water and could cause illness or infection to those coming in direct contact with the water through swimming or wading. Testing in Herrington Lake has shown E. coli levels to be consistently low and the lake to be safe for swimming. However, testing of the streams that flow into Herrington have shown some high levels of E. coli, much higher than the state’s safe swimming standard.  (The large volume of water in the lake is likely diluting the inputs from these streams.) Further testing to identify the source of these high E. coli levels has shown a mix of human and cattle sources, but also identified several locations where human sources are the greater contributor.  As these locations are mainly rural, it is believed that failing septic systems are leaking human sewage into the tributaries of Herrington Lake. HLCL is very concerned and encourages homeowners to repair damaged septic systems and abide by laws regarding the disposal of sewage from boats and floating houses.

Although Herrington Lake contains abundant fish populations for local fishing enthusiasts, there are some signs that its fisheries could be improved. High levels of nitrogen and phosphorus in the lake-- from sources such as crop and lawn fertilizers and septic and manure runoff, are contributing to the growth of algae in the lake. When the algae presence in the lake increases too much, it can lead to drops in the levels of dissolved oxygen in the water. Fish—like humans and other animals—rely on oxygen for survival. Thus, in certain areas of the lake and at certain times of the year, the fish and other aquatic animals become stressed by a limited oxygen supply and may become increasingly stressed or die off. It is recommended that nitrogen and phosphorus runoff sources to the lake be reduced to address this concern.

Some ways that lakeside landowners can help limit their contributions to the nitrogen and phosphorus entering the lake are:
     - Follow lawn and crop fertilizer application instructions carefully.
     - Reduce your need for added fertilizers by having your soils tested by your local County Extension Agent and using organic compost                        instead of chemical fertilizer applications.
     - Ensure that your septic system is functioning by having it pumped every 3 to 5 years and repairing any damaged drainage lines.
     - Clear fallen trees from the banks to prevent them from falling or washing into the lake.
     - Minimize paved areas that increase stormwater runoff to the lake. Rain gardens and other vegetated areas absorb runoff and allow

        it to sink into the ground, where it can be filtered through soil and plant roots.
     - Maintain a plant/shrub/tree buffer along the lake to help filter out stormwater runoff before it enters the lake.


Another water quality concern is mercury. The state of Kentucky has issued fish consumption advisories for fish taken from all waterbodies in the state, based on the level of mercury frequently found in fish tissues.

Statewide Guidance

The guidance below applies to specific groups of fish from all Kentucky waters:

Note: one meal is considered to be an 8 oz serving for a 150 pound person.
Sensitive Populations: Women of childbearing age and children 6 years and younger are advised to eat no more than six meals per year of predatory fish and no more than one meal per month of panfish and bottom feeder fish.  The general public is advised to eat no more than one meal per month of predatory fish and no more than one meal per week of panfish and bottom feeder fish. 
Predatory fish include: Largemouth Bass, Smallmouth Bass, Spotted Bass, White Bass and Striped Bass and their hybrids, Yellow Bass, Flathead Catfish, Blue Catfish, Musky, Sauger and Walleye and their hybrids, Bowfin, Chain Pickerel and all Gars.
Panfish include: Bluegill, Green Sunfish, Longear Sunfish, Redear Sunfish, Rock Bass, and Crappie species.     
Bottom feeder fish include: Channel Catfish, Drum, Carp Sucker, White Sucker, Common Carp, Bullhead species, Northern Hog Sucker, Buffalo species, Spotted Sucker, Redhorse species, Sturgeon and Creek Chub.
Other fish include: Asian Carp, Trout species, Minnows, etc.

Further details about the fish consumption advisory can be found at Mercury occurs naturally in the environment, but is also present due to electricity generation using coal and other fossil fuels.
After being emitted to the air by fossil fuel-fired power plants, mercury enters the water, and subsequently the tissues of aquatic animals. 


Another concern in Herrington Lake, as with several other Kentucky reservoirs, is the presence of harmful algal blooms (HABs). Although blue-green algae occur naturally in the environment and are a vital part of the ecosystem, they can explode in numbers when there are excess nutrients (nitrogen and phosphorus), sunny conditions, warm temperatures and low-flow or low-
water conditions. Several blue-green algae species can produce toxins, called cyanotoxins, which are harmful to the nervous system, liver and skin of humans and other animals. 


The more common green algae, which do not produce toxins, appear in many forms and may be seen as underwater moss or stringy mats. Blue-green algae, however, appear as slicks of opaque, bright green paint from a distance and have a grainy, sawdust-like appearance close-up. They may also appear red or brown.  


Although there aren’t currently any related advisories for HABs in Herrington Lake, the lake was being watched closely in the summer 2015 for related toxins and a potential advisory. More information is available at Additionally, the Kentucky Division of Water and Kentucky Watershed Watch began a pilot citizen lake sampling program in 2017 to help them track potential HAB occurrences in Herrington Lake and other lakes across Kentucky. More information is available by clicking here ( monitoring-program).

Solid waste is also a chronic issue in and around Herrington Lake. In addition to abandoned or dilapidated boat docks, woody debris and household waste is washed into the lake as its water levels fluctuate. The Herrington Lake Conservation League has been actively engaged in reducing floating trash in the lake through citizen clean-up events, and also hires contractual assistance with clearing and burning or removing woody debris from the lake. Lakeside residents can also do their part by picking up trash from their lawns, neighborhoods, and roadways.

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