Abstract Welch EB, Bouchard D, Frodge J, Jacoby JM. Stability of Lake Sammamish phosphorus despite land use changes. Lake Reserv Manage. 35:167–180. Total phosphorus (TP) concentration in Lake Sammamish has not changed significantly following recovery in the 1970s from wastewater diversion, despite increases in developed land and impervious area of 100% and 60%, respectively, from 1980 to 2011. Annual mean, whole-lake TP has remained constant at about 18 µg/L. Summer mean TP and chlorophyll a (Chl-a) have not changed either, and transparency increased from 3.8 m in the 1970s to consistently around 5 m since the 1980s. Reasons for the stability of annual mean TP through the 1980s were (1) hypolimnetic TP had declined by nearly 50% since the 1970s, due to 62% less internal loading; (2) water residence time increased slightly since the 1970s, allowing more settling of particulate matter; and (3) hypolimnetic TP content at turnover did not persist. In 1992, annual TP was predicted to increase from 18 to 28 µg/L if the watershed was developed to 64% from 36% as projected, without substantial forest retention and runoff controls. Developed land increased to half the watershed, but lake TP remained unchanged. Reasons for the continued stable TP over the subsequent 2 decades are that (1) use of land for agriculture ceased; (2) runoff controls were installed; and (3) more forest was retained (64% of the watershed that supplies 70% of the lake’s inflow remained 68% forested). With the implementation of runoff controls, concomitant with increased forest retention and decreased agriculture in the watershed, lake TP and water quality were more stable than originally predicted without these measures.

中文翻译：

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尽管土地利用发生变化，但萨马米什湖磷的稳定性

摘要 Welch EB、Bouchard D、Frodge J、Jacoby JM。尽管土地利用发生变化，但 Sammamish 湖磷的稳定性。湖泊保护区管理。35:167-180。尽管从 1980 年到 2011 年，已开发土地和不透水面积分别增加了 100% 和 60%，但在 1970 年代从废水分流中恢复后，Sammamish 湖的总磷 (TP) 浓度没有显着变化。 年平均，全湖TP 一直保持在 18 µg/L 左右。夏季平均 TP 和叶绿素 a (Chl-a) 也没有变化，透明度从 1970 年代的 3.8 m 增加到 1980 年代以来一直在 5 m 左右。1980 年代年平均 TP 保持稳定的原因是 (1) 自 1970 年代以来，由于内部负荷减少了 62%，水下 TP 下降了近 50%；(2) 水停留时间自 1970 年代以来略有增加，允许更多的颗粒物沉淀；(3) 周转时的潜水 TP 含量没有持续存在。1992 年，如果流域从预计的 36% 发展到 64%，而没有大量的森林保留和径流控制，那么年 TP 预计将从 18 µg/L 增加到 28 µg/L。已开发的土地增加到流域的一半，但湖泊总面积保持不变。随后 20 年 TP 持续稳定的原因是：（1）农业用地停止；(2) 安装了径流控制装置；(3) 保留了更多的森林（提供 70% 湖泊流入量的流域的 64% 仍然有 68% 被森林覆盖）。随着径流控制的实施，伴随着流域森林保留的增加和农业的减少，