This content requires Adobe Flash Player version
Either you do not have Adobe Flash Player installed,
or your version is too old,
or there is a problem with your Flash installation and we were unable to detect it.
Figure 2.4.13: The relationship between overall eutrophic condition, associated eutrophic symptoms and influencing factors Impact No Problem/low O2 Moderate low O2 Moderate Moderate high High Key to Symbols O2
Few symptoms occur at more than minimal levels.
Symptoms occur episodically and/ or over a small to medium area.
Symptoms occur less regularly and/or over a medium area.
Symptoms occur less regularly and/or over a medium to extensive area.
Symptoms occur periodically or persistently and/or over an extensive area.
O2 O2 Inuencin factors Source: Adapted from Bricker et al. 2008
which represent the most common causes of water quality degradation in North American waters. Nutrient-driven water quality problems in the region have generally outgrown the regulatory tools of the past and require new mechanisms for integrated water resource management.
Development of planning documents to control nutrients and restore waters has been increasing in the US since the Clean Water Act was passed in the early 1970s. Since then, individual states and the US EPA have developed more than 6 000 location-specific standards for nutrient total