Restoration and Management of Lakes and Reservoirs - Hydro-Environmental Analysis: Freshwater Environments - page 473

and nonpoint) are a component of all total maximum daily loads (TMDLs) studies. Quantifying
nutrient loads and impacts is also a necessary component of the recent and/or ongoing develop-
ment of nutrient standards by states. The advantage to lake management and restoration is that the
TMDLs and nutrient standards provide a link between, and regulatory control of, external sources
and in-lake quality.

17.4.2 I nternaL M anaGeMent
A variety of techniques can be used for the internal management and control of nuisance algae in
lakes, a number of which are listed in the following sections and described by NALMS (e.g., 1990,
2001; Table 17.1). It should be noted that many of these techniques are not effective over long peri-
ods unless they are implemented in conjunction with the management of external loads.

17.4.3 p HoSpHoruS I nactIVatIon
Phosphorus inactivation is typically intended to remove or reduce stored phosphorus in lakes by
adding salts of aluminum, iron, or calcium to the lakes to complex with and inactivate phosphorus.
Of these, aluminum is the most common and is a popular lake management tool (Cooke et al. 2005).
Aluminum salts, such as aluminum sulfate (alum), may be added to the water column or sediments
or both. In the water column, alum may precipitate the formation of locs (e.g., Al(OH) 3 at a typical pH
of 6-8; Cooke et al. 2005) that bind phosphorus and remove it via settling. As they settle, the locs also
remove other particulates (including phytoplankton), so that the water column transparency increases
as the locs settle. The locs on the sediment surface, or those added to the sediments, form a “blanket”
that binds and inhibits the release of phosphorus from the sediments (NALMS 1990; Holdren et al.
2001). One consideration is that the addition of alum tends to reduce the pH (the formation of AlOH),
which affects both its eficiency (greatest loc formation occurs between a pH of 6-8) and its toxicity
below pH = 6. For lakes with low alkalinities, it may be necessary to add a buffer, such as sodium
aluminate, along with the alum to act as a buffer and maintain a stable pH (Cooke et al. 2005).

TABLE 17.1
Comparison of Lake Management Techniques for the Control of
Nuisance Algae

Short-Term
Effect

Long-Term
Effect

Chance of
Negative Effects Cost

Phosphorus inactivation E E G L

Dredging F E P F

Dilution G G F L

Flushing F F F L

Artiicial circulation G ? G F

Hypolimnetic aeration F ? G F

Sediment oxidation G E F ?

Algicides G P G H

Food chain manipulation ? ? E ?

Rough ish removal G P E ?

Hypolimnetic withdrawal G G G F

Source: NALMS, The Lakes and Reservoir Restoration Guidance Manual , 2nd ed., North
American Lake Management Society, U.S. Environmental Protection Agency, Washington,
DC, 1990.
Note: E = Excellent, G = Good, H = High, F = Fair, P = Poor, L = Low, ? = not listed.